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    Fixture Unit Calculator (DFU / WSFU)

    What is the difference between DFU and WSFU?

    Drainage fixture units (DFU) measure the load a fixture places on drain and vent piping; water supply fixture units (WSFU) measure the demand it places on the supply system. They are not interchangeable — a fixture has separate DFU and WSFU values, and you size drains from DFU totals and supply pipe from WSFU totals.

    Run the numbers for your project

    Use the Fixture Unit Calculator (DFU / WSFU) to get an exact answer for your inputs.

    Open the calculator

    Related questions

    Estimates and general guidance only. Verify against your local code and AHJ before any installation. Gas, electrical, and refrigerant work is hazardous to untrained users.

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