Latitude and longitude to GARS
Encodes a latitude and longitude as a Global Area Reference System cell: 30′ cell, 15′ quadrant, or 5′ keypad, with its bounds.
The GARS reference is 381NH45.
- Center latitude
- Center longitude
- South edge
- West edge
- North edge
- East edge
Provenance
- Computed by
- geodesy.grid-ref.gars-forward 1.0.0, core 0.1.0
- Model
- GARS: 720 longitude bands from 180° W, 360 latitude bands from 90° S, quadrants and keypads numbered from the north-west
- Accuracy
- Identical to GeographicLib's GARS class on 1,218 points at every precision
- Notes
- None
- Cites
- National Geospatial-Intelligence Agency, Global Area Reference System (GARS); Karney, C. F. F., GeographicLib, GeographicLib GARS and Georef classes
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: GARS: 720 longitude bands from 180° W, 360 latitude bands from 90° S, quadrants and keypads numbered from the north-west
Accuracy: Identical to GeographicLib's GARS class on 1,218 points at every precision
When to use this: Use this when work is organized by GARS cells: search and rescue, military planning, and some agency products divide the world into thirty-minute cells with quadrants and keypads. This turns a latitude and longitude into that cell at the precision you pick, and gives the cell's bounds so you can see the area it covers.
Limitations: A GARS reference names an area, not a point: the coarsest cell is thirty minutes of latitude and longitude, which is tens of kilometers wide. The cells are defined on latitude and longitude, so their ground size shrinks toward the poles. It carries no datum of its own; coordinates are taken as WGS 84.
Worked example: GeographicLib's example point at 5′. Source: GeographicLib GARS documentation: 381NH45.
You enter
- Latitude
- 57.64911 deg
- Longitude
- 10.40744 deg
You get
- GARS
- 381NH45
- Center latitude
- 57.625°
- Center longitude
- 10.375°
- South edge
- 57.583333333°
- West edge
- 10.333333333°
- North edge
- 57.666666667°
- East edge
- 10.416666667°
Review: Not yet independently reviewed by a geodesist.
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Changes
- 2026-09-19, changed: The GARS, GEOREF, Maidenhead, and USNG tools are stable, both directions. They reproduce NGA's GARS band definitions, the Wikipedia GEOREF (NAS Patuxent River) and Maidenhead (W1AW) examples, and the FGDC USNG Washington Monument, and match GeographicLib, pygeodesy, an exact Maidenhead reference, and NGA GEOTRANS on thousands of points. Results are unchanged apart from the fix below. Changelog
Checked against: 23 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Global Area Reference System (GARS), National Geospatial-Intelligence Agency, NGA GARS web description. 30-minute cells, 15-minute quadrants, 5-minute keypads.
- GeographicLib GARS and Georef classes, Karney, C. F. F., GeographicLib, GeographicLib 2.x. GARS.cpp and Georef.cpp: encoding, decoding, and precision rules. Read free.
Terms
- GARS: Global Area Reference System
- A worldwide grid of 30-minute cells, split into 15- and 5-minute quadrants and keypads, used to name areas. Source: Global Area Reference System