Plumbing Calculators
Last updated: October 2026
Hot Water Recirculation Calculator
Estimates the recirculation flow rate needed to offset heat lost from a hot water loop, from pipe length, diameter, insulation and the acceptable temperature drop.
Pipe Flow Velocity Calculator
Calculates the average flow velocity of fluid in a circular pipe given a volumetric flow rate and pipe diameter.
Fixture Unit Demand Calculator
Computes the total plumbing demand load in fixture units for toilets, sinks, showers, and appliances, then converts it to a peak flow estimate for pipe sizing.
Pipe Flow Rate Calculator
Determine the flow rate of water through a pipe using the Hazen-Williams equation.
Sump Pump Sizing Calculator
Determine the minimum sump pump capacity (GPM) needed to protect your basement given its area, local peak rainfall, soil drainage, and discharge lift height.
Water Meter Sizing Calculator
Determines the smallest standard water meter size (in inches) whose AWWA rated maximum flow covers your peak demand and whose pressure loss fits the pressure you can spare.
Pipe Insulation Thickness Calculator
Estimates the required insulation thickness for a pipe based on its diameter, the temperature difference between the pipe and surroundings, and whether the pipe is indoors, outdoors, or in a crawl space.
Grease Trap Sizing Calculator
Determine the minimum grease trap size (in gallons) for a commercial kitchen based on sinks, dishwashers, meal volume, kitchen type, and required retention time.
Water Pressure Drop Calculator
Calculates the residual water pressure (PSI) at the end of a piping run after accounting for elevation changes, pipe friction loss, and fittings.
Pipe Expansion Joint Calculator
Calculate how much a straight pipe run grows or shrinks with a temperature change, ΔL = L × 12 × ΔT × α, for steel, copper, stainless, aluminum, PVC or ABS.
Faucet Flow Rate Calculator
Calculates a faucet's flow rate in gallons per minute (GPM) by timing how long it takes to fill a known container.
Plumbing Fixture Unit Calculator
Add up the drainage fixture units (DFU) for every toilet, sink, shower, bathtub, and appliance in a building to find the correct supply and drain pipe sizes per plumbing code.
Toilet Flush Volume Calculator
Computes the volume of water used per flush by measuring the internal dimensions of the toilet tank.
Water Pump Sizing Calculator
Calculate the required pump power output in horsepower given flow demand, total dynamic head, and pump efficiency.