Tool
Grid Square Calculator
Coordinates to Maidenhead and back, plus distance and bearing between two grids.
Your browser asks first, and the coordinates never leave this page — there is no server call here at all.
How the locator works
The Maidenhead system divides the world into a nested grid, adding precision two characters at a time.
- Two letters — the field, 20° of longitude by 10° of latitude.
FMcovers a large chunk of the US east coast. - Two digits — the square, 2° by 1°.
FM05is roughly 100 × 70 miles. - Two more letters — the subsquare, 5′ by 2.5′, about 3 × 3 miles.
- Two more digits — about 800 × 500 yards.
Four characters is what you exchange on FT8 and what counts for most awards. Six is normal on VHF and for anything where a few miles matters. Longitude always gets twice the span of latitude, because degrees of longitude converge at the poles while degrees of latitude do not.
Note what this means for privacy: a four-character grid tells someone roughly which metropolitan area you are in, and a six-character one narrows you to a few square miles. Eight characters puts you on a street. Most operators publish four or six and stop there.