Compass Reciprocal Calculator
Compute back bearing in degrees and mils with true, magnetic, and grid reference conversions.
🧭Field Presets
⚙Input System
📊Quick Conversion Grid
📘Reference Tables
| Forward Azimuth | Reciprocal Azimuth | Quadrant Bearing | Quadrant Reciprocal |
|---|---|---|---|
| 032 deg | 212 deg | N 32 E | S 32 W |
| 087 deg | 267 deg | N 87 E | S 87 W |
| 141 deg | 321 deg | S 39 E | N 39 W |
| 279 deg | 099 deg | N 81 W | S 81 E |
| Reference Input | To True Formula | To Magnetic Formula | To Grid Formula |
|---|---|---|---|
| True | True = Input | Mag = True - Decl | Grid = True - Conv |
| Magnetic | True = Mag + Decl | Mag = Input | Grid = True - Conv |
| Grid | True = Grid + Conv | Mag = True - Decl | Grid = Input |
| Reciprocal | Rec = angle + 180 | Normalize 0..360 | Apply chosen ref |
| Degrees | NATO Mils | Warsaw Mils | Common Use |
|---|---|---|---|
| 45 | 800 | 750 | NE diagonal line |
| 90 | 1600 | 1500 | Due east leg |
| 180 | 3200 | 3000 | South return |
| 270 | 4800 | 4500 | West relocation |
| Declination Zone | Typical Range | Field Rule | Risk if skipped |
|---|---|---|---|
| Low shift | -2 to +2 deg | Apply exact sign | Small drift over distance |
| Moderate shift | -6 to +6 deg | Convert every leg | Missed return point |
| High shift | -12 to +12 deg | Track map date too | Large route bias |
| Extreme shift | Above 12 deg | Double check bearing | Major nav error |
Find the mutual direction of a compass is practical resource for navigation in the natural surroundings.
A mutual bearing is that direction that is exactly 180 degrees different than your present course. For instance, reciprocal of North is South, so 180 degrees. For bearing of 110 degrees the reciprocal do 290 degrees, while for 300 degrees it will be 60 degrees.
How to Find the Opposite Direction on a Compass
Easy mode recall that they always sum to 360 degrees.
Are fast modes count those values in the head. One popular effect is add 200 and remove 20, or vice versa. Other way is observe the figures: if the first is 2, remove 2 and add it to the second.
For 297 degrees result 117, because the 7 stay same. For course as 29, add 2 to 9 for 11, so mutual course 11. This counts for all bearings starting by means of 2, for instance 29, 28, 27 or 20.
You can also determine the reciprocal by means of compass rose on compass or HSI. At physical compass matter keep it level and line up with your body. Turn it until the north needle coincide with the white triangle before S, for find the mutual course.
If you require to recall the back direction, compass with bezel are better for that. Some favour map-application that shows bearings as North, South, East or West, or they download compass-application from app-store.
Different utilities have different advantages. Liquid filled and robust models are usual, but those with mirror and folding cover can be more practical. Cammenga lensatic compasses fames because of his indestructible construktion, that does not slacken because of induction and do not have bubbles.
Suunto is other brand with global needle. Are seriously know that compass for the south hemisphere will not operate well in the north. Compass best are usefull when you combines it with chart.
