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Compass app with mils: read a bearing in degrees and NATO mils

Open Tactical tools on the map and QUICK COMPASS shows you which way you're pointed, in degrees true and in NATO mils both at once. The conversion underneath is mils = degrees × 6400 / 360, which is why 247° comes out as 4391 mils.

3 min read · Updated 2026-09-23

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Why bother with mils at all

Military and artillery work splits the circle into 6,400 NATO mils instead of 360 degrees. One mil at 1 km is about 1 m to the side, a convenient coincidence that makes range and correction maths fast in your head. Land nav classes teach both, which is reason enough to see them side by side instead of converting on a scrap of paper.

How to read degrees and mils in FieldGrid

  1. On the Map tab, open Tactical tools from the side buttons.
  2. Hold the phone flat and point its top edge where you want to measure.
  3. Read QUICK COMPASS at the top of the sheet: a 3-digit heading with °T and the same heading in mils.
  4. For a bigger rose, tap the compass row in the tools list. The Compass screen adds a 16-point cardinal direction and the GPS accuracy.

The conversion, if you want to do it yourself

Degrees to mils: multiply by 6400, divide by 360, roughly ×17.78. Mils to degrees: multiply by 360, divide by 6400, roughly ×0.05625. Or let the app do it.

Degrees to NATO mils, rounded as FieldGrid shows them
DegreesNATO mils
0° (north)0
45°800
90° (east)1600
180° (south)3200
247°4391
270° (west)4800
360°6400

Going the other direction inside the app: press and hold WP+, pick By distance and bearing…, type a bearing in mils, and the footer shows degrees. 1200 mils comes out as ≈ 67.5° true; 300 mils as ≈ 16.9° true.

6,400 isn't the only mil circle out there

FieldGrid runs the NATO circle, 6,400 to the full turn. Some armies use 6,000, and the mathematical milliradian circle sits around 6,283. Confirm which one your own compass or course uses before mixing numbers from different sources.

Can you actually trust a phone compass?

It's a magnetometer in a phone, not a lensatic compass. No sighting wire, no declination or grid-magnetic angle setting, no magnetic readout on an iPhone at all. Fine for checking a direction or orienting on the map. Easily thrown off by metal, magnets in a case or mount, and nearby vehicles, which can push a reading 40° off.

  • Take readings away from vehicles, rebar, rifles and magnetic phone cases.
  • If the number drifts, wave the phone in a figure-eight away from metal and let iOS recalibrate.
  • Check it against a real compass on a known bearing before trusting it on a course.

Questions and answers

Does FieldGrid show magnetic or true north?
True north, marked °T, whenever the phone can actually give it. No declination setting, and no magnetic readout on an iPhone at all.
How many mils in a circle in FieldGrid?
6,400, NATO standard. That puts 90° at 1,600 mils and 180° at 3,200.
Can I use it on a land navigation course instead of a lensatic compass?
Cross-check with it, don't replace the issued compass with it. Most courses require the real thing anyway, and a phone can run several degrees off near metal.
Is there a compass on the Apple Watch app?
Yes. It is labelled MAG, but it also shows true heading when the watch provides it.

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