Declination Calculator
Calculate grid-magnetic angle and convert bearings for UTM/MGRS maps
Specifications
- Input
- G-M angle from the map (° + direction)
- Map format
- UTM / MGRS (military maps)
- Conversion
- GMAG and MAGG
- Available in
- All plans (free tool)
How it works
Military and topographic maps (UTM/MGRS) have a grid-magnetic angle (G-M angle) printed on them. This is the difference between grid north and magnetic north. Because this difference changes slightly each year, you calculate the current G-M angle based on the map year and the annual change. With the GMAG/MAGG tool you then convert a grid bearing to a magnetic bearing — or vice versa — in one step.
What you get
- Calculate the current G-M angle from map data
- GMAG: convert grid bearing to magnetic bearing
- MAGG: convert magnetic bearing to grid bearing
- Annual change included in the calculation
- Fully offline — no internet required
- Works with any UTM or MGRS map worldwide
Try it yourself
Grid Angle & Bearing Converter
Enter the details from your map and instantly calculate the current grid angle and the converted bearing.
Declination Calculator
Grid angle + KAKO / KOKA conversion
Calculate the current grid angle based on map data and convert directly to a map or compass bearing.
Conversion direction
Base grid angle (from the map)
Annual change
Frequently asked questions