Fixture Unit & Pipe Size Calculator
Add fixtures (or load a preset) to estimate peak demand and the pipe, meter and drain sizes it implies. Planning values based on the Uniform Plumbing Code.
Good to know
What is a water supply fixture unit (WSFU)?
A WSFU is a load factor the plumbing code assigns to each fixture based on its flow, duration and how often it's used. Adding them up and running the total through Hunter's curve gives a realistic peak demand instead of assuming everything runs at once.
Why does the calculator use PEX inside diameters?
PEX has a smaller inside diameter than copper of the same nominal size, so sizing for PEX is the conservative case for Central Texas homes, where PEX is the most common supply pipe.
Can I use this for permit drawings?
No. It's for planning and sanity checks. Permit drawings need the full method in the code your city adopted, including developed length, elevation and pressure loss through meters and backflow devices.
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