Plumbing calculators
18 calculators across 4 pillars. Every one runs entirely in your browser — nothing you type is transmitted anywhere — and every code table behind them names its section and edition.
Sizing and flow
6 calculatorsPipe size calculatorSize a water supply run from fixture units, developed length and available pressure.1/2"–2" · IPC 604Drain slope calculatorFall 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 704Fixture unit calculatorTotal WSFU and DFU for a fixture list, both codes side by side.WSFU · DFUGas pipe size calculatorSchedule 40 and CSST sizing by BTU load and longest length.NFPA 54 · in. w.c.Water pressure calculatorStatic head, elevation loss and friction loss to a PSI at the fixture.PSI · ft headHot water wait time calculatorSeconds to hot, gallons in the line and water run to drain, by pipe and flow.Cu · PEX · CPVC · IPC 607.2
Costs and estimating
5 calculatorsWater heater cost calculatorTank size, fuel, permit and haul-away into one installed band.40–80 gal · USDRepipe cost calculatorFixtures, stories and material into labour hours and a material band.PEX · CPVC · CuPlumbing invoice templateEditable, printable invoice with line items, tax and terms.Print · CopyJob price calculatorFlat-rate build-up from labour rate, material, overhead and margin.Flat rate · %Plumbing contract templateEditable residential contract: scope, payments, change orders, permits, warranty.Print · Copy
Code and permits
3 calculatorsVent distance calculatorMaximum trap arm length by size, with the fall check that fails most inspections.IPC 906.1Expansion tank calculatorTank volume from heater capacity, temperature rise and supply pressure.gal · PSIPermit checklist builderScope in, printable list of drawings, forms and inspections out.Print · Edit
Fixtures and repairs
4 calculatorsWater heater sizing calculatorPeak-hour demand into a gallon size, or a tankless GPM at your rise.FHR · GPMLeak cost calculatorDrip rate into gallons a year and dollars at your own water rate.gal/yr · USDSump pump sizing calculatorTimed pit rise and discharge run into the gpm at head a pump curve must meet.gpm · ft TDHWater softener size calculatorHousehold use, hardness and iron into grains, then resin size at your salt setting.gpg · ft³ · lb salt
Keep the code book handy.
Bookmark the calculator you reach for most. It will be there on the next callout, with the table it reads from named on the page.
Read the guides