Rise and Fall Levelling Worksheet
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
Field book
| BS | IS | FS | Remark | |
|---|---|---|---|---|
First row needs a backsight (BS). A change point has both a foresight (FS) and the new backsight (BS). Runs in your browser — nothing is uploaded.
Reduced levels — Rise & Fall
| Remark | BS | IS | FS | Rise | Fall | RL |
|---|---|---|---|---|---|---|
| BM (start) | 2.000 | 100.000 | ||||
| Station 1 | 1.500 | 0.500 | 100.500 | |||
| CP | 1.800 | 0.500 | 1.000 | 101.500 | ||
| BM (end) | 1.000 | 0.800 | 102.300 |
✓ Arithmetic check balances — the columns agree.
How to use this calculator
- Enter the starting reduced level (RL) of your first benchmark.
- Type each field-book reading into the BS, IS or FS column in order. The first row needs a backsight; a change point has both a foresight and the new backsight.
- Add or remove rows to match your run, then read the reduced levels and the arithmetic checks.
How it works
The Rise and Fall worksheet reduces a level run by comparing each reading with the previous one: a smaller reading is a rise, a larger one a fall, and the reduced level carries forward as RL = previous RL + rise − fall.
It then runs the standard three-way check: the sum of backsights minus the sum of foresights should equal the sum of rises minus the sum of falls, which should equal the last RL minus the first RL. When all three agree, the arithmetic balances.
Worked example
BS 2.000 at RL 100.000, change point, FS 1.000. With a change point (FS 0.500, BS 1.800) then FS 1.000, the run rises to RL 102.300, and ΣBS−ΣFS = ΣRise−ΣFall = last−first RL = 2.300 — so it balances.
Tips
- Rise and Fall checks every intermediate sight, so it's the safer method for runs with many IS readings.
- The arithmetic check proves the reduction, not the fieldwork — a balanced run can still contain a reading blunder.
Frequently asked questions
What is a change point?
A change point is where you move the level. You take a foresight to a stable point from the old setup, then a backsight to the same point from the new setup — so that row has both an FS and a BS.
The check doesn't balance — what's wrong?
Usually a reading typed in the wrong column (BS vs IS vs FS), a missed change-point backsight, or a transcription error. The three sums must agree; if they don't, re-check each row against your field book.
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.