Fixture Unit Calculator

Estimate plumbing fixture units for water supply or drainage planning. Calculate total fixture units, adjusted fixture units, estimated demand, fixture load, fixture count totals, and rough pipe sizing guidance for plumbing systems.

Calculate Fixture Units

Total Fixture Units = Fixture Count × Fixture Unit Value.
Your result will appear here.

How the fixture unit calculator works

Single fixture type:
The calculator multiplies fixture count by the selected fixture unit value.

Fixture group:
The calculator multiplies the number of fixture groups by the units per group.

Custom fixture units:
The calculator uses your custom fixture unit total and applies simultaneous use and safety factor adjustments.

Demand estimate:
The calculator converts fixture units into a rough estimated demand for planning.

Why use a fixture unit calculator?

A fixture unit calculator helps estimate the plumbing load created by sinks, toilets, showers, tubs, laundry fixtures, floor drains, bathroom groups, and other plumbing fixtures.

It can help compare fixture count, fixture unit value, total fixture units, adjusted units, estimated flow demand, and rough pipe sizing guidance.

What your result means

Your result shows an estimated fixture unit total and adjusted fixture unit load. Fixture unit values are code-sensitive and can vary by fixture type, private or public use, water supply design, drainage design, pipe material, and local plumbing code. Use this as a planning estimate only.

Fixture unit formulas

Frequently asked questions

What is a fixture unit?

A fixture unit is a plumbing design value used to estimate the load or demand created by a plumbing fixture.

Are drainage fixture units and water supply fixture units the same?

No. Drainage fixture units are used for waste and drain sizing, while water supply fixture units are used for water supply demand and pipe sizing.

How do you calculate fixture units?

Multiply the number of fixtures by the fixture unit value for each fixture type, then add the totals together. Code tables should be used for final values.

Is this fixture unit calculator exact?

No. This calculator gives a planning estimate. Final plumbing fixture unit calculations should follow local plumbing code and be checked by a qualified plumber or designer.