Benchmark Transfer Planner
Plans differential levelling runs from a benchmark to site, estimating setups, sight lengths and allowable misclose.
Run details
k is your spec's levelling accuracy constant (e.g. 12 mm√km for general site levelling). Keep backsight and foresight lengths balanced.
Plan
Set-ups ≈ distance ÷ (2 × sight length); allowable misclose = k × √(distance in km). Run a loop (there and back) and check the closing misclose against this allowance.
How to use this calculator
- Enter the distance from the benchmark to site and your maximum sight length.
- Set the allowable accuracy constant k (mm/√km) from your spec.
- Read the number of set-ups and the allowable misclose for the run.
How it works
Each instrument set-up covers a backsight and a foresight, so it advances roughly twice the sight length: set-ups ≈ distance ÷ (2 × sight length).
The allowable misclose grows with distance as k × √(distance in km) — the standard √-of-length rule for levelling.
Worked example
800 m at 50 m sights, k = 12. ≈ 8 set-ups, and an allowable misclose of 12 × √0.8 ≈ 10.7 mm for the run.
Frequently asked questions
What k should I use?
Use the value in your project spec. Around 12 mm√km suits general site levelling; precise/control levelling is much tighter (e.g. 2–5).
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.
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Cite this tool
Zerdly. (2026). Benchmark Transfer Planner. Retrieved from https://www.zerdly.com/tools/benchmark-transfer-planner/
Tip: Enter any known values to calculate the remaining results.
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