Pool Pump Size Calculator

Sizing a pool pump takes two numbers, and most people only work out the first. Enter the pool volume and a turnover period for the flow in gallons per minute, then enter the pipe size, run length, fittings, static lift and equipment losses for the total dynamic head that flow has to be pushed against, worked out with Hazen-Williams and checked for water velocity. A third tab turns flow and head into watts, daily kilowatt-hours and a running cost, and shows what halving the speed does. Head is the part that gets skipped, and it is why an oversized pump costs money without moving more water.

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Measurements In
The metric setting reads the pool in litres, the flow in cubic metres an hour and every head figure in metres of water, which is how a European pump curve is published, and returns them the same way. The pipe list is separate: it carries both Schedule 40 inch sizes and metric PVC-U sizes, because those are different products rather than the same pipe in two units.
In US gallons, or in litres if the measurement choice is metric. Length x width x average depth x 7.48 for a rectangle in feet, or x 1000 for one in metres.
Eight hours is the usual residential target. Public pools are often held to six or less by health code.
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Measurements In
The metric setting reads the pool in litres, the flow in cubic metres an hour and every head figure in metres of water, which is how a European pump curve is published, and returns them the same way. The pipe list is separate: it carries both Schedule 40 inch sizes and metric PVC-U sizes, because those are different products rather than the same pipe in two units.
In GPM, or in cubic metres an hour if the measurement choice is metric. 1 to 500 GPM, or 0.23 to 113.56 m3/h.
Schedule 40 inch sizes and metric PVC-U sizes are different pipes with different bores, not the same pipe in two units, so both lists are here and the measurement choice does not change them. Pick the one you actually have.
In feet, or in metres if the measurement choice is metric.
In feet, or in metres if the measurement choice is metric. Negative if the pump sits below the water line, which is a flooded suction and helps.
In feet, or in metres if the measurement choice is metric. A clean cartridge filter is around 3 to 8 ft (0.9 to 2.4 m), sand 5 to 10 ft (1.5 to 3 m), DE 7 to 12 ft (2.1 to 3.7 m); a heater adds 5 to 10 ft (1.5 to 3 m) and a salt cell 2 to 4 ft (0.6 to 1.2 m). A dirty filter can double its share. Blank means 15 ft, or 4.5 m.
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Measurements In
The metric setting reads the pool in litres, the flow in cubic metres an hour and every head figure in metres of water, which is how a European pump curve is published, and returns them the same way. The pipe list is separate: it carries both Schedule 40 inch sizes and metric PVC-U sizes, because those are different products rather than the same pipe in two units.
In GPM, or in cubic metres an hour if the measurement choice is metric.
In feet, or in metres of water if the measurement choice is metric. 1 to 200 ft, or 0.3048 to 60.96 m.
Pump and motor together. A single-speed pool pump is commonly 40 to 55 per cent; a good permanent-magnet variable-speed pump reaches the high 60s.
A kilowatt hour is a kilowatt hour in either system, so this box does not change.
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