MapTools Knowledge Base

Thirty years of teaching search-and-rescue teams and park rangers to read a map — now searchable. Ask anything.

Example — a question and its answer

“How do I select a geographic coordinate system?”

I don't have information in the MapTools Knowledge Base about selecting a geographic coordinate system — that is, how to decide which one is best for your situation based on your needs.

What I can tell you is that once you know what your peers or your context uses, you should use that system. The main options are:

Lat/lon — the universal default; most GPS receivers ship with this as the factory setting.
UTM — raw numerical form (easting and northing in meters), best for survey work and GIS.
MGRS — alphanumeric form with a 100km square prefix; standard for military, allied military, and SAR.
USNG — the civilian U.S. equivalent of MGRS, used by FEMA and emergency response.

The guidance is: pick the system your teammates are using, then worry about ergonomics. Mismatched systems between teammates are how coordinates get mistransmitted.

If you're trying to decide between these for a specific activity or context, I'd need more detail about what you're doing — but the principle is coordination first, preference second.