Pool Volume Calculator

Pool volume formulas by shape.

Rectangular pool:

• Volume = Length x Width x Average Depth x 7.48 (for US gallons)
• Volume = Length x Width x Average Depth (for cubic feet)

Round pool:

• Volume = Radius2 x Pi x Average Depth x 7.48

Oval pool:

• Volume = (Long Radius x Short Radius) x Pi x Average Depth x 7.48

Average depth = (Shallow End + Deep End) / 2

Conversion factors:

• 1 cubic foot = 7.48 US gallons = 28.317 liters
• 1 US gallon = 3.785 liters

Typical pool volumes:

• Small above-ground (12 ft round, 4 ft deep): 3,400 gallons (12,870 L)
• Medium in-ground (16x32 ft, 5 ft avg): 19,200 gallons (72,700 L)
• Large in-ground (20x40 ft, 6 ft avg): 35,900 gallons (135,900 L)
• Olympic pool (50x25 m, 2 m deep): 660,000 gallons (2,500,000 L)

The number that makes or breaks a pool-volume estimate is average depth, and it’s the one people get wrong. A pool that slopes from 3 feet to 8 feet doesn’t hold as much as its deep end suggests; you average the two to get 5.5 feet, then calculate from that. Skip this step and you can overestimate the volume by a third, which matters because almost every pool chemical is dosed by the gallon.

That’s really why you’d want this number at all. Chlorine, stabilizer, algaecide, and pH adjusters all come with instructions like “add X per 10,000 gallons,” so an inflated volume means you overspend and overshoot, while a lowball figure leaves the water under-treated. The 7.48 in the formulas is simply the gallons in a cubic foot. Measure your pool once, write the gallon figure inside the equipment cabinet, and you’ll never have to redo this math every time you open a bottle.