Free Tool · Land Surveying · Closed Traverse · Bowditch Compass Rule

Traverse Closure & Bowditch Adjustment

Compute angular misclosure, apply Bowditch (compass rule) corrections, and get fully adjusted station coordinates for a closed traverse. Enter interior angles and leg lengths — the engine distributes the angular error, computes adjusted azimuths, latitudes/departures, linear misclosure, and precision ratio 1:N, then applies Bowditch corrections to give final coordinates.

Traverse Input
Stations, Angles & Distances

Interior angles of a closed polygon must sum to (n − 2) × 180°. Any difference is the angular misclosure.

Station Interior angle (°) Distance to next station (m)

Worked example: 5-station traverse (textbook reference). Adjust values to compute your own.

Worked example result
FAIL Precision 1:39 vs required 1:5000
Angular misclosure1.2830°
Correction per angle-0.256600°/station
Linear misclosure34.9905 m
Total traverse length1355.0 m
Precision ratio1:39
Precision ratio1:39 / required 1:5000
Leg Summary (preview)
Station Azimuth (°) Latitude (m) Departure (m)
A→B 25.00° 232.5117 103.1137
B→C 106.76° -82.0159 293.6862
C→D 174.76° -272.1843 22.7105
D→E 240.32° -91.9268 -171.3984
E→A 310.08° 213.6152 -248.1120
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Traverse Results
Angular misclosure
Correction per angle
Linear misclosure
Total traverse length
Precision ratio
Precision ratio
Leg Summary (preview)
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Full coordinate table, CSV export and PDF report available with a Civil plan — View plans →

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FAQ

What is traverse closure?

A closed traverse is a series of survey lines that return to the starting point. "Closure" refers to how well the surveyed legs actually close — the sum of latitudes and departures should be zero. The difference is the linear misclosure, expressed as a precision ratio (1:N, where larger N is better). A 1:5000 precision means the misclosure is 1 unit per 5000 units of total traverse length.

What is the Bowditch (compass) rule?

The Bowditch rule (also called the compass rule) distributes the linear misclosure in proportion to leg length. The latitude correction for each leg is −(leg length / total length) × ΔN, and the departure correction is −(leg length / total length) × ΔE. It is the standard adjustment method for traverses where angular and linear measurements are of equal precision. The transit rule (distributing in proportion to lat/dep magnitude) is preferred when angular precision greatly exceeds distance precision.

What accuracy class should I use?

ISO / national survey standards define accuracy classes by minimum precision ratio. Third order (1:1000) suits local detail surveys and boundary runs. Second order (1:5000) is standard for engineering control. First order (1:10000) is used for primary control networks and precise deformation monitoring. Geodetic order (1:50000 and above) is for national and continental-scale triangulation networks.

How do I enter angles in degrees-minutes-seconds?

Convert to decimal degrees: DD = degrees + minutes/60 + seconds/3600. For example, 105°20'00" = 105 + 20/60 = 105.333°. Most modern total stations output decimal degrees directly. The calculator also accepts decimal-degree input directly — simply type the decimal value.