Pool Volume Calculator

Work out your pool's volume in US gallons and litres from its shape and measurements.

Pool volume formulas

Volume = surface area × average depth. Average depth is (shallow depth + deep depth) ÷ 2. One cubic foot holds 7.48 US gallons; one cubic metre holds 1,000 litres.

• Rectangle: length × width × average depth × 7.48 = gallons
• Round: 3.1416 × (diameter ÷ 2)² × average depth × 7.48 = gallons (≈ diameter² × depth × 5.87)
• Oval: 3.1416 × (length ÷ 2) × (width ÷ 2) × average depth × 7.48 = gallons (≈ length × width × depth × 5.87)
• Metric: use metres in the same formulas and multiply cubic metres by 1,000 for litres.

Example

A 32 × 16 ft rectangular pool, 3.5 ft at the shallow end and 6.5 ft at the deep end, has an average depth of 5 ft: 32 × 16 × 5 = 2,560 ft³ × 7.48 ≈ 19,150 gallons (about 72,500 litres). A 24 ft round above-ground pool with 4.5 ft of water holds about 15,230 gallons.

Tips

• Measure the water depth, not the wall height — above-ground pools are rarely filled to the top.
• For a pool with a gentle slope followed by a steep drop, split it into sections, calculate each, and add them up.
• Freeform and kidney pools: approximate as a rectangle or oval using average length and width. The result is an estimate, so add salt in stages.
• If you know how long your pool took to fill and your hose's flow rate, that is a good cross-check.