Obviously change the reference to suite. Write a TSQL function to convert NAD83 State Plane (specifically ESRI Projection 102738 http://spatialreference.org/ref/esri/102738/) to WGS84 Lat/Lng so I can, in near real-time, plot the original coordinates on a Google Map. In areas of sparse geodetic data coverage, NADCON may yield less accurate results but seldom in excess of 1.0 m. Transformations between NAD83 and the States/Regions with High Accuracy Reference Networks (HARN) introduce approximately 0.05 m uncertainty. Copyright 2000-2023 Groundspeak, Inc. DBA Geocaching. (e.g. Even today, geodesists are continually improving horizontal geodetic datums. Where To Buy Maps Online: An Insiders Guide, 50 Map Projections Types: A Visual Reference Guide [BIG LIST], Esri JavaScript API Examples: 15 High-Tech Webmaps and Webscenes, 10 Topographic Maps From Around the World. What is the incorrect result for your conversion. Right-click total to add Max, Min, Count, Average. But that is not a correct transformation: A place in your backyard should remain in your backyard, regardless of the CRS you are using. Geodetic datums like the North American Datum 1983 (NAD83) form the basis of coordinates of all horizontal positions for Canada and the United States. Making Maps: A Visual Guide to Map Design for GIS Users can select different grids by clicking on the "select grid" link below. I checked the properties of the layers, and one says +datum=WGS84, while the other says +datum=NAD27. Also, it happens when there are more of them and methods of geodesy change. February 8, 2002 in GPS technology and devices. If you are marking property boundaries, building roads, or planning for coastal inundation scenarios, you must know about and use the correct geodetic datums. But given that the datum of the coordinate matches the datum used on the map, you will see no difference in the physical location. convert nad27 to wgs84 formula. MERCEDES Projected coordinate systems are based on geographic coordinates, which are in turn referenced to a datum. When you need to accurately enter latitude and longitude coordinates in a GIS, the first step is to give it a datum. Thanks for contributing an answer to Geographic Information Systems Stack Exchange! All input and output linear units are in meters. I have an issue going on the pro4js github: You absolutely right about the issue that proj4js does not have a datum shift grid function included. Remarks: Parameter file is from NAD27 to NAD83 (4) (code 1313) assuming that NAD83 is equivalent to WGS 84 within the accuracy of the transformation. Cartisan Maps site is now dead (domain name grabbed by someone else); however, I have uploaded the two files to MediaFire, and updated the links to the spreadsheets to point to these files. Problems with NAD27 included measurement errors and intentional distortions. A coordinate transformation is done through a series of mathematical equations. I had previously found that it sometimes had to be deleted, reloaded to work. No plugin or software installation is required for you.. Powered by Aspose.GIS. We have a great community of people providing Excel help here, but the hosting costs are enormous. 3. Because where would you be on Earth without having reference to it? Clear editor. A geodetic datum uniquely defines all locations on Earth with coordinates. If you are marking property or land boundaries or building roads or planning for coastal inundation scenarios, you must know about and use the correct geodetic datums. 10 Topographic Maps From Around the World, Ocean Currents Map: Visualize Our Oceans Movement, Esri JavaScript API Examples: 15 High-Tech Webmaps and Webscenes, 50 Map Projections Types: A Visual Reference Guide [BIG LIST]. Having failed to recently update I delete them attempted to download again. Most overview landmarks have not moved. Projection: 32629 Home | Upload Your Own | List user-contributed references | List all references The currently accepted method is an error averaging, rubbersheeting approach. The best answers are voted up and rise to the top, Not the answer you're looking for? The following projection file converts an NAD27 dataset to an NAD83 dataset in Canada: Why y-coordinates may seem 200 meters too large. (I zoomed in to 47:1. Projected coordinate systems are based on geographic coordinates, which are in turn referenced to a datum. Am I missing something obvious? For convenience, a link is included to the National Geodetic Survey's NADCON program, which allows conversions between the NAD83 / WGS84 coordinate system and the older NAD27 coordinate system. Datum shifts happen because survey measurements improve. Log in . All functionality are processed using Our APIs, which are being used by many Fortune 100 companies across 114 countries. How can I take a NAD27 decimal coordinate like 39.748303,-104.998634 and convert it to NAD83 or WGS84 with a programming function in PHP or JS? Comments are currently closed; feel free to contact me with questions/issues. The horizontal datums that form the basis of coordinates of all horizontal positions in North America improve. It provides latitude and longitude and some height information using the reference ellipsoid GRS80. November 18, 2021 called a datum transformation (or coordinate system transformation). It runs with any browser on any device. Turn off on-the-fly transformations for you project and load the saved NAD27(BLM14) file in. We begin modeling the Earth with a sphere or ellipsoid. Transformations between old datums (NAD27, Old Hawaiian, Puerto Rico, etc.) 1. There is a basic ellipsoidal projection, but then you are supposed to apply offsets from one of several gigantic tables (basically 200 years of empiracly derived and measured data). Similar to NAD 83, it uses the Earths center mass as the coordinate origin. United States and Canada is where I'm converting. The total appears in bottom right of Excel screen. The latitudes and longitudes of every other point in North America were based on its direction, angle, and distance away from Meades Ranch. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? you should have the on-the-fly projection setting turned on this could be the answer to the discrepancy question. http://everest.hunter.cuny.edu/mp/software.html. Cartisan Total Map Coordinate Converter: Converts from decimal and DDMMSS latitude/longitude to UTM and MGRS, and back again; includes support for 14 datums, including NAD27 and WGS84. List of supported states in Accuracy and uncertainty. If you have an account, sign in now to post with your account. By I converted NAD27 to NAD83 and put on google maps and it was about the same as WGS84 (maybe 5-8 ft difference). This is a result of the difference between the size and origin of the two spheroids on which the data is being projected. North American Datum of 1927 (NAD27) and the North American Datum of 1983 (NAD83). Here's an example. This conversion uses the Esri transformation NAD_1927_To_NAD_1983_NADCON. The first thing you should be careful of is that the physical locations have not changed. You have successfully reported the error, You will get the notification email when error is fixed. This conversion generally is accurate within about 0.5 feet for 95 percent of the study area. a mammoth collection of monument locations, mathematical techniques like triangulation, NOAAs National Geodetic Survey used these survey stations and triangulation. It provides latitude and longitude and some height information. Should I use the NADCON converter at http://www.ngs.noaa.gov/cgi-bin/nadcon.prl to convert my WGS84 coordinate data to NAD27? Upload or insert images from URL. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The National Geodetic Survey relied heavily on the use of the Doppler satellite to locate the Earths center of mass. To learn more, see our tips on writing great answers. The Canadian National Transformation predicts to within 0.01 meters of the actual difference for 74 percent of the cases, and within 0.5 meters for 93 percent of the cases. - Mintx Aug 4, 2016 at 21:42 This difference is known as a datum shift. For application in Gulf of Mexico refer to IOGP report 373-26. The normal revision somewhere in the range of NAD27 and NAD83 is a normal of 0.349 northward and 1.822 eastbound. It is known locally as the National Transformation and will be referred to in this document and the software as the Canadian National Transformation. Result is 39.748289809487346 -104.99917122555918. i made the assumption that ellps value unchanged without knowing what extact projection your data is in. If a law is new but its interpretation is vague, can the courts directly ask the drafters the intent and official interpretation of their law? Thanks for contributing an answer to Stack Overflow! (I never took any GIS classes in school, and I've only been working at this for a few weeks.). But where can I find the origin alignment, axis rotation, and scale information that will allow me to relate Clarke 1866, GRS80, and WGS84? The first sentence you wrote perhaps is wrong that the lat long taken from Google maps are not in WGS84 rather they are in NAD27. - YouTube GIS: Convert NAD27 to WGS84 with programming function like PHPHelpful? Proj.4 is pretty good, but a perfect example of why I hate to design and execute by committee (with all due respect to the folks overseeing it!). geographic transformations and how to choose the right one, 25 Map Types: Brilliant Ideas to Build Unbeatable Maps, Epic Web Maps The Maps Hall of Fame [Best Maps]. Making statements based on opinion; back them up with references or personal experience. Geodesists developed the NAD83 datum using approximately 250,000 stations. When you do click on the datum, it shows various parameters that it uses. All files are processed on our servers. Get your coordinates in the WGS84 on your display. developers.google.com/maps/documentation/javascript/, How Intuit democratizes AI development across teams through reusability. To more clearly see the difference, relative to your Google Maps points (which may be in a different CRS), load the layer, defining it as having a CRS as WGS84 (probably accurate), then right-click on the layer and choose Save As, defining your project CRS of NAD27(BLM14) for the resultant file. 2. To learn more, see our tips on writing great answers. NAD 27 and NAD 83 provide a frame of reference for latitude and longitude locations on Earth. You may have on-the-fly transformations on for your project. Your email address will not be published. Learn more about Stack Overflow the company, and our products. In 1983, surveyors eventually replaced the NAD27 with NAD83. Has 90% of ice around Antarctica disappeared in less than a decade? A datum defines the following parameters for an ellipsoid: The North American datum of 1983 (NAD83) is the current horizontal or geometric datum for the United States. Download the free Excel template to perform the following operations: - Conversion of UTM Coordinates to Decimal Degrees. Is there a proper earth ground point in this switch box? This datum uses the Clarke Ellipsoid of 1866 with a fixed latitude and longitude at Meades Ranch, Kansas. Thus, when the receiver tell us that the computed coordinates using GPS observations are referred to the WGS84, they actually mean WGS84(G1150). Have you attempted anything on your own? The latitude and longitude location in the NAD27 datum differs from NAD83 or WGS84. NGS Coordinate Conversion and Transformation Tool (NCAT) Convert/Transform from: Horizontal+height Select the type of horizontal coordinate: + Leaflet | Sources Esri, DeLorme, HERE, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), MapmyIndia, and the GIS User Community Enter lat-lon in decimal degrees Lat Lon You would need to apply a datum transformation when working with NAD83 data. GDAL/OGR are fairly robust and open source that are made for this. On the other hand, if we use CORS coordinates data, or the OPUS service, the NAD83 reference frame to which these You can open imagerywith a world file. A horizontal datum provides a frame of reference as a basis for placing specific locations at specific points on the spheroid. If you preorder a special airline meal (e.g. You should see the difference between the projections, i.e. Especially, this is true when using historical data. My project data is in NAD27(BLM14). Can I tell police to wait and call a lawyer when served with a search warrant? Adoption of the North American Datum (NAD) of 1983 requires that you store and use map data in a coordinate system based on NAD83. var NAD2NAD = function (x,y) { var NAD27= "+proj=longlat +ellps=WGS84 +datum=NAD27 +no_defs"; var NAD83= "+proj=longlat +ellps=WGS84 +datum=NAD83 +no_defs"; return proj4 (NAD27,NAD83, [x,y]); }; your input in NAD27 39.748303,-104.998634, Proj4js returns in datum NAD83 [ -104.998634, 39.74619740515981 ], It was a purchased app but recently failed to update. In surveying and geodesy, we accurately define these properties with geodetic datums. Assigning the CRS does not transform the data. How do you ensure that a red herring doesn't violate Chekhov's gun? SPCS DEMs SPCS imagery I don't need to be perfect. Can anyone recommend a good app for multiple datum transformations? What is the correct way to screw wall and ceiling drywalls? Learn more about Stack Overflow the company, and our products. One of the primary differences is that NAD83 uses an Earth-centered reference, rather than a fixed station in NAD27. High Accuracy Reference Network (HARN) and High Precision Geodetic Network reworked geodetic datums from 1986 to 1997. Terms of Use | Privacy Policy ", "United States (USA) - Delaware and Maryland. and HARN could combine uncertainties (that is, NAD27 to HARN equals 0.15 m + 0.05 m = 0.20 m). There is no exact mathematical equation that will convert data built from a surface oriented local datum like NAD27, to an earth centered global datum like NAD83. If any of . Where does this (supposedly) Gibson quote come from? A minimum curvature-derived surface based on the National Geodetic Reference System determines the transformation of points and has an approximate accuracy of 0.15 to 0.5 meters. Connect and share knowledge within a single location that is structured and easy to search. Cartisan Map Coordinate Converter: Enter latitude and longitude in separate columns for degrees, minutes and seconds, and have them converted to a DD MM SS string, DD MM.d string, or numeric decimal degrees. ", "(null/copy) Approximation for medium and low accuracy applications assuming equality between plate-fixed static and earth-fixed dynamic CRSs, ignoring static/dynamic CRS differences. Choose lat long, decimal degrees, UTM, or state plane coordinates as your input format. The Global Positioning System (GPS) references the World Geodetic System (WGS84) as its coordinate reference system. Answer: EPSG4326 is just the way to identify WGS84 using EPSG. We reference all coordinates on Earth to a datum. How to convert WGS84 to NAD27 in pygeodesy? It consists of a reference ellipsoid, a standard coordinate system, altitude data, and a geoid. This has led to the development of global ellipsoid models such as WGS72, GRS80, and WGS84 (current). Area of use: United States (USA) - Delaware and Maryland. This converter applet will convert a single pair of UTM coordinates to latitude/longitude using formulas and constants for the North American Datum of 1927 (NAD27, Clarke Ellipsoid of 1866). Is a list of projection packages, many public domain with source. We reference all coordinates on Earth to a horizontal datum. For example, USGS topographic maps generally were published using a NAD27 datum. Proper gdaltransform syntax to transform a list of coordinates? After you get two sets of coordinated in a common datum, there are three steps to get them in alignment: Remember next time in ArcMap when you use the project tool. Data can be post as file or as an URL link - as well as the result. Input the coordinates in a decimal degrees (DD) format. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. NADCON, an acronym for North American Datum Conversion, is a datum transformation program created by the U.S. National Geodetic Survey (NGS). I have to process millions of records, so an API would likely be too slow. Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? Enter 1 for East longitudes, -1 for West longitudes, and make sure your longitude degree value is always positive; or, enter a 1, and then enter positive and negative values for the longitude degree value. United States (USA) - Delaware and Maryland. Making statements based on opinion; back them up with references or personal experience. This will give you access to the Nadcon box at the bottom of the window, where you must click the Browse button to locate the conus.las file obtained in Step 1. - Conversion of Coordinates in Degrees, Minutes and Seconds to Decimal Degrees. The mapping platform for your organization, Free template maps and apps for your industry. Using this app is a fast and easy way to get coordinates in the WGS84 by automatically converting the coordinates of any Spatial Reference System (SRS) or EPSG code. To see this for yourself, you can create a coverage of a single arc, running along a meridian from the equator to your point of interest in the coterminous United States. The best method these days is using distortion models which I believe is used with things like NADCON, http://www.ngs.noaa.gov/TOOLS/Nadcon/Nadcon.html. I see the list of files here: https://github.com/DotSpatial/DotSpatial/tree/master/Source/DotSpatial.Projections/Nad/GridShifts Which one do I use, if any? Have you research the problem? Scope: (null/copy) Approximation for medium and low accuracy applications assuming equality between plate-fixed static and earth-fixed dynamic CRSs, ignoring static/dynamic CRS differences. What am I doing wrong here in the PlotLegends specification? Why does Mister Mxyzptlk need to have a weakness in the comics? See also: Proper gdaltransform syntax to transform a list of coordinates? Click Add. Surveyors referenced al coordinates to Kansas Meades Ranch (391326.686 north latitude, 983230.506 west longitude) for the NAD27 datum. Surveyors now rely almost exclusively on the Global Positioning System (GPS) to identify locations on the Earth and incorporate them into existing geodetic datums. This tool permits the user to convert latitude and longitude between decimal degrees and degrees, minutes, and seconds. The hour between square brackets is compulsory to display a. For example, the National Geodetic Survey has adjusted the NAD83 datum four times since the original geodetic datum estimation in 1986. NOAAs National Geodetic Survey used these survey stations and triangulation to form the NAD27 datum. After, geodesists developed the more accurate NAD 83, which we still use today. I'll investigate the information you have all provided and see if it helps. The challenge is to get points in different datums to align. Benchmarks refer to elevation only and not to geographic position. In this case, a datum transformation is necessary. To transform datums, specify different input and output datums with the DATUM subcommand in a projection file. For example, surveyors benchmarked approximately 250,000 stations. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Linear Algebra - Linear transformation question. To convert into various coordinate formats, we freely offer our Excel template. Your email address will not be published. This results in more accurate geodetic datums over time. The Add Coordinate Format dialog will appear. Your NAD83 coordinates turn into WGS84 less than a minute. Why does Mister Mxyzptlk need to have a weakness in the comics? It may not display this or other websites correctly. In case you have coordinates in CSV file somewhere online, you can call this request: Thanks for contributing an answer to Geographic Information Systems Stack Exchange! Your email address will not be published. NAD 27 and NAD 83 provide a frame of reference for latitude and longitude locations on Earth. An example is 52 12. vegan) just to try it, does this inconvenience the caterers and staff? What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? For example, the State Plane Coordinate System can be referenced to either NAD83 and NAD27 geodetic datums. There also may be problems running this in Excel, as it seems to want a password for some functions; however, it runs fine on the free Office clone LibreOffice.. Cartisan Maps has several free spreadsheet tools for basic coordinate conversions; each one can handle up to 5000 sets of coordinates. How to notate a grace note at the start of a bar with lilypond? Unfortunately, NAD83 is not the only datum youll encounter. Required fields are marked *, Datum Transformations Converting Coordinates from NAD27 to NAD83. In near offshore regions, results will be less accurate but seldom in excess of 5.0 m. Farther offshore, NAD27 was undefined. Where does this (supposedly) Gibson quote come from? Does ZnSO4 + H2 at high pressure reverses to Zn + H2SO4? If you are looking for online API solution, you can use MyGeodata Cloud API - you can send data in many GIS formats and set transformation to any known projection and conversion to many GIS formats. I work offshore and dont always have a good internet connection with which to update my apps so I do that from good WiFi before departure. By default, it will be created on the Clarke 1866 spheroid. Your previous content has been restored. Macro/VBA to add text from another cell into current cell when I type a certain value. North American Datum of 1983 is based on the reference ellipsoid GRS80 which is physically larger than NAD27s Clarke ellipsoid. One of the most clear, concise, descriptions I have read. Because that is incorrect: How to transform data points from WGS84 to NAD27? Asking for help, clarification, or responding to other answers. Select a popular spatial reference system from the drop-down list or choose a custom system to enter the functioning EPSG code by yourself. datums. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? The WGS84 datum. Pasted as rich text. There is a basic ellipsoidal projection, but then you are supposed to apply offsets from one of several gigantic tables (basically 200 years of empiracly derived and measured data). Farther offshore NAD27 undefined. Most survey monuments have not moved. your ~ 50 meters. The first geodetic datum adopted for the United States was based on the Clarke ellipsoid with its starting point in Kansas known as Meades Ranch. This will only work in the area of validity of NAD27, that is Northern America. The photo shown is a benchmark, not a triangulation station. If so then it does the transformation for you. Copyright 2000-2023 Groundspeak, Inc. DBA Geocaching. convert nad27 to wgs84 formula. Convertir coordenadas UTM NAD27 a WGS84 en ArcGIS - YouTube 0:00 / 6:33 Introduccin Convertir coordenadas UTM NAD27 a WGS84 en ArcGIS ngel A. Gonzlez 35 subscribers Subscribe 36. Proj4js returns in datum NAD83 [ -104.998634, 39.74619740515981 ], From http://tagis.dep.wv.gov/convert/ Not the answer you're looking for? The NAD27 datum was based on the Clarke Ellipsoid of 1866: The NAD83 datum was based on the Geodetic Reference System (GRS80) Ellipsoid: For any type of work where coordinates need to be consistent with each other, you must use the same geodetic datum. Unfortunately, NAD27 is not a simple mathmatical formula. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The default NAD27 to WGS84 transformation is NAD_1927_To_WGS_1984_1, . The average correction between NAD27 and NAD83 is an average of 0.349 northward and 1.822 eastward. Assigning the CRS does not transform the data. If you have 'On-the-fly-reprojection' enabled, you should see the difference between WGS84 and NAD27 for the same coordinate pair: But note that you should use EPSG:4267 NAD27 for this, and not EPSG:32064 NAD27-BLM14, which has US feet as units. Are you suggesting that Google Maps uses the NAD27 datum? The coordinates for the same location are different. Identify those arcade games from a 1983 Brazilian music video. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, var functionName = function() {} vs function functionName() {}, Reference Guide: What does this symbol mean in PHP? Currently, all states have been resurveyed. Geodesists use a horizontal datum as the model to translate a spheroid/ellipsoid into locations on Earth with latitude and longitude lines. Surveyors could measure any point with a latitude and longitude away from this reference point based on the Clarke Ellipsoid of 1866. Canadian Spatial Reference System and Canadian Active Control System with GPS processing. NAD27 coordinates are presently used for broadcast authorizations Earth bulges out more at the equator than at the poles by about 70,000 feet. Some samples are: Easting (Metre): 398676. help with formula to convert GPS degrees minutes seconds to decimal degrees. It is suitable for the United States, Puerto Rico, and the Virgin Islands but only for conversion between the NAD27, NAD83, High Precision GPS Network (HPGN) readjustment of NAD83, and selected local island datums discussed below. Be forewarned that NAD27 is complicated with all of them. As the name implies, datum transformations transform your data from one datum to another. The North American Datum of 1927 (NAD27) is one of the main three geodetic datums in North America. After, geodesists developed the more accurate NAD 83, which we still use today. This way, if you construct your lon/lat data as a csv with one coordinate pair per line, like. It appears after finishing the conversion process. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. There is an ongoing effort at the state level to readjust the NAD83 datum to a higher level of accuracy using state-of-the-art surveying techniques that were not widely available when the NAD83 datum was being developed. Due to differences in the method for defining each datum, as well as variations in distortion, the relationship between the NAD27 datum and NAD83 datum cannot be defined at every location by a single mathematical equation. Notes: 1. For example, State Plane coordinate systems can either reference the NAD83 or NAD27 geodetic datums. A datum describes the shape of the Earth in mathematical terms. Now project it and change the datum to NAD83. Select a range of cells. The horizontal datums that form the basis of coordinates of all horizontal positions in North America improve. rev2023.3.3.43278. none. En el botn select coordinate System elegimos el sistema de orgen. Each works best for a particular region. Over time, surveyors have gathered a massive collection of surface measurements to more reliably estimate the ellipsoid. I've been asked by some users of my Spreadsheet if i could add the the conversion from WGS84 to NAD27. Chris, try this link out http://www.gpsu.co.uk/. We reference all coordinates to a datum. If your data is already in NAD27, do not use these options. Or convert them to any other coordinate I can map onto tableau. Map Tools was a great little app and I used it quite a bit, especially for datum transforms. Exploring the world of free tools for GIS, GPS, Google Earth, neogeography, and more. Is it possible to rotate a window 90 degrees if it has the same length and width? NAD27 is the adjustment of long-baseline surveys. Powered by Invision Community. If so, your WGS84 points were automatically reprojected (or projected in this case) to NAD27(BLM14). From the unified network of survey monuments, the result of triangulation was the North American Datum of 1927 (NAD 27). A geographic coordinate system (GCS) is a coordinate system associated with positions on Earth (geographic position). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Continually Operating Reference Stations (CORS) are composed of permanently operating Global Positioning System (GPS) receivers. The UTM system divides the Earth into 60 zones, each 6 of longitude in width. Surveyors gathered approximately 26,000 stations in the United States and Canada. Steps of transformation: How can we prove that the supernatural or paranormal doesn't exist? JavaScript is disabled. The arc should be approximately 200 meters longer. NAD83 is a geocentric datum (referenced to the center of Earths mass) offset by about 2 meters. I've been trying to do this for days. This compares to the Clarke ellipsoid with a semi-major axis of 6,378,206.4 m and a semi-minor axis of 6,356,583.8 meters. Using QGIS, I loaded my shapefile into one layer and set the CRS to WGS84, then I loaded the same data again and set its layer to NAD27. If you are converting to or from state plane, use the NAD27 keyword instead. I've been asked by some users of my Spreadsheet if i could add the the conversion from WGS84 to NAD27. UTM (Universal Transverse Mercator) is a coordinate system that is based on the WGS84 ellipsoid. READ MORE: Datum Transformations Converting Coordinates from NAD27 to NAD83, Image credit: NADCON North American Datum Conversion Utility, Clarke 1880 was never used in North America. Thanks in advance. However, because the geodetic datums were different, the resulting projected coordinates will also be different. That is why you dont see any difference.