Pipe Length Calculator
Work out how much pipe to buy — straight length plus elbow allowances and wastage — and how many standard pipe lengths that means.
Buying pipe is not just the straight length — elbows cost length, and cuts cost waste. This calculator adds them all up and tells you how many standard pipes to buy.
Enter the run; the shopping list follows.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Enter the straight length of the run.
- Enter the number of elbows and the equivalent length per elbow.
- Set the wastage allowance and the standard pipe length.
- Read the total length, the pipes needed and the offcut.
Worked example
| Straight length | 25 m |
|---|---|
| Elbows | 4 × 0.5 m = 2 m |
| Before waste | 25 + 2 = 27 m |
| With 10% waste | 27 × 1.10 = 29.7 m |
| Pipes (3 m each) | ceil(29.7 ÷ 3) = 10 pipes |
| Offcut | 10 × 3 − 29.7 = 0.3 m |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
What is the equivalent length of an elbow?
The straight-pipe length that causes the same friction loss as the fitting. It depends on the diameter and the fitting type — 0.5 m is a common guide for small pipe. Enter your own figure if you know it.
Why add wastage to pipe?
Because cuts leave offcuts, and a run rarely lands exactly on a pipe length. 10% is normal; complex runs with many cuts need more.
What is the offcut?
The piece left over from the last pipe — 0.3 m in the example. Keep it: it is the spare for the next repair.
Is this a substitute for plumbing design?
No. This is a quantity calculation for planning. Pipe sizing, pressure and code compliance depend on local regulations and real installation conditions — see the safety notice.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.