Perpendicular Offset Survey Table Builder
A free, browser-based tool. Runs entirely in your browser — no sign up, nothing stored.
Baseline
Offsets
Chainage runs along the baseline; offset is perpendicular — positive to the right of the direction of travel, negative to the left.
| Chainage (m) | Offset (m) | |
|---|---|---|
Coordinates
| Chainage | Offset | Easting | Northing |
|---|---|---|---|
| 0.000 | 0.000 | 1000.000 | 2000.000 |
| 25.000 | 5.000 | 1021.213 | 2014.142 |
| 50.000 | -4.000 | 1032.527 | 2038.184 |
How to use this calculator
- Enter the baseline start coordinates and bearing.
- Add a row per point: its chainage along the baseline and its perpendicular offset (right positive, left negative).
- Read each point's easting and northing.
How it works
Each point steps along the baseline by its chainage, then perpendicular by its offset: E = startE + chainage·sin(brg) + offset·sin(brg+90°), and similarly for N with cosines.
It's the classic offset detail-survey method turned into coordinates.
Worked example
Due-east baseline. On bearing 90° from (1000, 2000), chainage 50 with a +5 m (right) offset lands at E 1050.000, N 1995.000.
Frequently asked questions
Which way is a positive offset?
To the right of the direction of travel along the baseline. Use a negative offset for the left.
Is this official course material?
No. It is free study support mapped to surveying course levels — not official North Metropolitan TAFE content or advice. Always follow your lecturer and the official assessment brief, and check your own working.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.