FREE TOOL
Level Book Reduction Calculator
Enter back, intermediate and fore sights to reduce levels by the height-of-instrument method, with an arithmetic check.
| # | BS | IS | FS | HI | Level |
|---|
Method: height of instrument. The check covers back and fore sights only.
How to use this tool
- Enter the level of the first point, usually the benchmark.
- Enter one line per point, in order: back, intermediate, fore. Leave unused cells empty, such as 1.5,, or ,2.0, or 1.2,,1.0 for a change point.
- Press Calculate to see the levels and the arithmetic check.
FAQ
What is the arithmetic check?
The sum of back sights minus the sum of fore sights must equal the difference between the last and first levels. It catches calculation errors only, not reading errors on site.
What is a change point?
A point where a fore sight is read before moving the level, then a back sight after setting it up again.
How do I know the levelling is acceptable?
Close the run on a known benchmark and compare the closure error with the limit in the project specification.