Closed Level Loop Adjustment Allocator
A free, browser-based tool. Runs entirely in your browser — no sign up, nothing stored.
Loop sections
One row per section, in order around the loop back to the start. ΔH is the observed height difference; distance sets the share of the correction.
| To | Observed ΔH (m) | Distance (m) | |
|---|---|---|---|
Adjusted loop
| To | Obs ΔH | Correction | Adj ΔH | RL |
|---|---|---|---|---|
| BM-A | 1.000 | -0.010 | 0.990 | 50.990 |
| BM-B | -0.500 | -0.010 | -0.510 | 50.480 |
| Start | -0.470 | -0.010 | -0.480 | 50.000 |
Correction per section = −misclose × (section distance ÷ total distance). A guide for study — check your allowable misclose against your spec before adjusting.
How to use this calculator
- Enter the start (known) RL.
- Add a row per section around the loop — the observed height difference and the section distance.
- Read the misclose and the adjusted ΔH and RLs that close the loop.
How it works
A closed loop returns to its start, so the observed height differences should sum to zero. Any leftover is the misclose.
The correction is spread by distance: section correction = −misclose × (section distance ÷ total distance), so longer legs absorb more.
Worked example
A +0.030 m misclose over 300 m. Three 100 m sections each take −0.010 m, and the run closes back to the start RL.
Frequently asked questions
Distance or number of setups?
Either can model the share of error — distance is the usual choice. If you'd rather weight by setups, enter the setup count in the distance column.
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.