Traverse Adjustment Bowditch

The Traverse Adjustment Bowditch calculator takes a closed land-survey traverse and balances it: it finds the closure error the same way the Survey Traverse Closure Calculator does, then distributes that error across every leg using the Bowditch (compass) rule, so each station ends up with a corrected bearing, distance, and coordinate.

How to use it

1. Enter one leg per line, as a whole-circle bearing (0–360°, measured clockwise from north) and a distance, separated by a comma: 45.5, 120.3.
2. Order the legs the way you walked the traverse, station to station, back to the start.
3. Optionally set the starting station's northing and easting — leave both at 0 to place the start at the origin.
4. Read the closure error, then the per-leg adjustment table: each leg's raw bearing/distance, its Bowditch correction, its adjusted bearing/distance, and the running adjusted coordinates of every station.

What the Bowditch rule does

A closed traverse should return exactly to its starting station, but real measurements never quite do — the closure error is the residual gap. The Bowditch (compass) rule assumes that error is spread evenly across all the measurements, so it corrects each leg's latitude (north-south) and departure (east-west) components in proportion to that leg's own length relative to the traverse's total perimeter: a long leg absorbs more of the correction than a short one. Formally, for a leg of length d_i out of perimeter P:

correction_lat_i = -ΣLatitude  × (d_i / P)
correction_dep_i = -ΣDeparture × (d_i / P)

Adding each leg's correction to its raw latitude/departure gives the adjusted values; accumulating those from the start station produces the adjusted coordinate of every station in turn — and because the corrections are built to exactly cancel the original closure error, the last station lands back on the first.

Is my data private?

Yes. The entire calculation runs locally in your browser — your survey data is never uploaded to a server.

Why does the closure table AND the adjustment table both matter?

The closure table tells you whether the traverse is good enough to adjust (a 1:1,000 precision ratio usually means re-measuring, not adjusting). The adjustment table shows how the correction was distributed, leg by leg, so you can see exactly what changed on each line rather than only a final adjusted list.

What if my bearings are quadrant bearings (like N45°E), not whole-circle azimuths?

Convert them to a 0–360° whole-circle bearing first (N45°E → 45°, S45°E → 135°, S45°W → 225°, N45°W → 315°) — this tool expects the whole-circle format throughout.

Common uses

Balancing field survey notes after checking closure, producing final adjusted coordinates for a boundary or cadastral traverse, and documenting the per-leg correction applied for a survey report.