Transverse Mercator Calculator
A facility for converting latitude/longitude co-ordinates to co-ordinates in metres on a
Transverse Mercator projection. An Excel Workbook is also available on this page to carry out bulk conversions.
- The results of using the calculator provided on this page are believed to be accurate to 1
metre, but the accuracy is not in any way guaranteed.
- The results will certainly not, however, be accurate to 1 metre in situations where lat/long co-ordinates are based on a geodetic datum which is different from that used in the selected conversion.
- Do not enter negative values for lat/long co-ordinates west of Greenwich or south of the
equator. Specify W or S instead.
- There are few validity checks on the input data.
- For UTM conversions, the option exists for automatic calculation of the Central Meridian or manual entry of the Central Meridian. The calculation assumes that the standard UTM longitude zones are 6 degrees wide, except for the special zones around Svalbard and south-west Norway. For projections outside of the standard UTM zones you should manually enter the Central Meridian for the projection required.
TM_LL Excel Workbook:
An Excel Workbook (for Excel 97 or later) is available for converting between Latitude / Longitude co-ordinates and metric Easting / Northing on a Transverse Mercator Projection. This Workbook contains ready-made Functions which perform these calculations. The Workbook is set up with example Worksheets which demonstrate the use of these Functions and which can be easily modified using standard Excel operations to suit your needs. For example, you can enter your lat/long or easting/northing or grid reference data in columns on a worksheet and use the supplied Functions to automatically create columns containing the converted data.
For the UTM Grid and the National Grids of Britain, Ireland, Finland, Italy and Sweden, it will:
For the UTM Grid and the National Grids of Britain and Ireland, it will:
- Convert Latitude and Longitude to Easting and Northing in metres.
- Convert Easting and Northing in metres to Latitude and Longitude.
The following conversions are supported in the Workbook:
- Convert Latitude and Longitude to Grid References (MGRS and National).
- Convert Grid References (MGRS and National) to Latitude and Longitude.
There are also datum shift functions in the Workbook which convert geographical co-ordinates between WGS84, the datums listed above, and the following additional datums: NAD27 Central America, NAD27 North America, ARC 1950 Zimbabwe, Luzon Philippines (excluding Mindanao), Luzon Philippines (Mindanao).
|British National Grid||OSGB 1936||Modified Airy
|Irish National Grid||Ireland 1965||Modified Airy
|Swedish National Grid||RT90||Bessel 1841
|Italy Zone 1||Rome 1940||International 1924
|Italy Zone 2||Rome 1940||International 1924
|Finland Uniform Grid||KKJ||International 1924
|Hong Kong 1980||HK80||International 1924
|UTM Grid International 1924||e.g. ED 1950||International 1924
|UTM Grid WGS 1984||WGS 84||WGS 84
|UTM Grid Clarke 1880||e.g. Arc 1950||Clarke 1880
|UTM Grid Clarke 1866||e.g. NAD 27||Clarke 1866
By using the conversion Functions together with the datum shift Functions, Grid Reference and Easting/Northing co-ordinates can be converted to Lat/Long co-ordinates on the WGS84 datum used by modern mapping facilities such as Google Maps.
The cost of this Workbook is £15 and it can be obtained by paying for it by Debit Card or Credit Card on the PayPal Secure Server by clicking on the button below:
If you have any problem with paying via PayPal, or if you have any questions about the Workbook, Contact Alan Morton. Please note that if you use PayPal, Cookies need to be enabled in your Browser.
When you have paid for this Workbook, it will be sent to you promptly as an email attachment, usually within 24 hours, but please note that there may be delays due to staff holidays during late July and early August.
Equations and Source Code:
If you are interested in the equations involved in converting between geographic co-ordinates (latitude/longitude) and various projections, including Transverse Mercator, the following site is recommended:
Program source code is available for converting geographic co-ordinates (latitude/longitude) to metric co-ordinates and vice versa on a Transverse Mercator projection (Including the UTM, British, Irish, Swedish, Italian and Finnish grids). The source code is available in Visual Basic at a cost of £80. The Visual Basic code is the VBA source code which implements the functions supplied in the TM_LL Excel Workbook, and it is a requirement that purchasers of this source code also purchase the TM_LL Excel Workbook itself.
To purchase the VBA source code by Debit Card or Credit Card on the PayPal Secure Server click on the button below:
If you have questions about the source code, or about alternative methods of payment, Contact Alan Morton
For visitors who have come to this page directly rather than from the DMAP home page:
The following additional page on this site may be of interest to you:
Also, you are invited to visit the DMAP home page which describes the DMAP software for Distribution Mapping:
Comments or suggestions about this facility are invited and can be sent to Alan Morton