Plumbing Calculators
Last updated: September 2026
Water Heater Size Calculator
Estimates the recommended water heater tank capacity in gallons based on household size and hot water usage habits.
Water Pressure Loss Calculator
Calculates friction-induced pressure drop along a water pipe using the Hazen-Williams equation.
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.
Water Heater Sizing Calculator
Estimates the peak-hour hot water demand (First Hour Rating target, in gallons) for a household from occupants, bedrooms, bathrooms and usage pattern.
Septic Tank Size Calculator
Estimates the minimum septic tank capacity needed for a household based on bedroom count and daily water usage.
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.
Drain Pipe Slope Calculator
Calculates the required vertical drop for a drain pipe based on its length and diameter to ensure proper self-cleaning flow.
Septic Tank Sizing Calculator
Estimates the minimum septic tank volume (in gallons) needed for a home based on bedroom count, occupants, plumbing fixtures, and daily wastewater generation.
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.
Drainage Pipe Slope Calculator
Calculates the required slope and total vertical fall of a drainage pipe to achieve self-cleaning sewage flow over a given horizontal distance.
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
Calculates how much a pipe will elongate or contract due to a temperature change, using the thermal expansion coefficient of carbon steel, copper, aluminum, or PVC.
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.
Grease Trap Size Calculator
Determines the required grease trap (interceptor) capacity in gallons based on the number of connected fixtures, their individual flow rates, and the required grease retention time.
Toilet Flush Volume Calculator
Computes the volume of water used per flush by measuring the internal dimensions of the toilet tank.
Pipe Friction Loss Calculator
Calculates pressure loss (in PSI) due to pipe friction using the Hazen-Williams equation, given flow rate, pipe length, diameter, and material.
Water Pump Sizing Calculator
Calculate the required pump power output in horsepower given flow demand, total dynamic head, and pump efficiency.