Construction

Plumbing Pipe Length Calculator

Estimate total pipe to buy from a straight run plus a percentage allowance for fittings and bends.

Straight pipe run (m)
Fittings allowance (%)

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The "Pipe to order" result is the total length of pipe to buy in metres, including the extra allowance for fittings and bends.

Formula

Pipe to order = straight run multiplied by (1 plus fittings allowance as a decimal).

How it works

Measure the straight pipe route, then add a percentage for bends, drops, connections and offcuts. The allowance keeps a job from stalling for one short length, though complex routes with many fittings need a larger allowance.

Worked example

For example, a 10 m straight run with a 15% fittings allowance gives 10 × (1 + 15/100) = 11.50 m of pipe to order.

FAQs

How large should the allowance be?
Fifteen percent suits a simple run. Routes with many bends, tees and drops may need twenty to twenty-five percent.

Does this count fittings themselves?
No, it estimates extra pipe length only. Fittings are counted and ordered separately.

What about vertical drops?
Include every vertical section in the straight run measurement before applying the allowance.

Rough estimate only — consult a licensed professional for structural work before building.