Plumbing calculators

Each calculator runs in your browser and shows its math and sources. Use the results to plan and to check a quote. A licensed plumber should confirm sizing, gas line and electrical needs before you buy.

• Water heater size calculator

  Find the first hour rating your tank water heater needs from your busiest hour of hot water use, using the DOE and AHRI peak hour worksheet.

• Tankless water heater size calculator

  Size a tankless water heater by flow rate and temperature rise. Get the gallons per minute you need, plus the gas BTU or electric kW to heat it.

• Water leak calculator

  Count the drips per minute or enter a leak rate, add your water rate, and see the gallons and dollars a leaky faucet or toilet wastes per year.

• Pipe volume calculator

  Find how many gallons of water a run of copper, PEX or Schedule 40 PVC pipe holds, using the real inside diameters from the ASTM tube and pipe tables.

• Whole-house repipe cost estimator

  Estimate what it costs to repipe a house with PEX or copper, by floor area and by fixture count, using published national cost ranges.