Sizing and flow
5 tools · 4 guides · 1 comparisons · 10 pages
Pipe sizing, drain slope, fixture units and pressure — the numbers you dimension before a single fitting is sweated.
IPC 604
Calculators
Pipe size calculatorIPC 604
Size a water supply run from fixture units, developed length and available pressure.
1/2"–2" · IPC 604
OpenDrain slope calculatorIPC 604
Fall over a run at 1/8, 1/4 and 1/2 inch per foot, with the code minimum for the size.
1-1/4"–8" · IPC 704
OpenFixture unit calculatorIPC 604
Total WSFU and DFU for a fixture list, both codes side by side.
WSFU · DFU
OpenGas pipe size calculatorIPC 604
Schedule 40 and CSST sizing by BTU load and longest length.
NFPA 54 · in. w.c.
OpenWater pressure calculatorIPC 604
Static head, elevation loss and friction loss to a PSI at the fixture.
PSI · ft head
OpenGuides
Pipe size chartNominal versus actual diameter for copper, PEX, CPVC, PVC and steel.8 minHow pipe size is measuredWhy nominal never matches your caliper, and how to identify a line on site.7 minDrain pipe slope per footCode minimums by size, the too-steep myth, and how to shoot a grade.8 minPlumbing fixture units explainedWSFU and DFU, what they actually count, and a worked house.9 min
Comparisons
Keep the code book handy.
Every table on this site is dimensioned, sourced and dated. Bookmark the calculator you use most and it will be there on the next callout.
Open the calculators