Construction Calculator - Water and Utility

Pool Volume Calculator

Estimate water in a rectangular pool from length, width, and the average of its shallow and deep depths.

Reviewed: August 26, 2026

Rectangular swimming pool with a tape measure along the coping and a depth staff in the water
Measure inside waterline dimensions and use representative shallow and deep depths.

Calculate Pool Volume

For the Pool Volume Calculator, enter pool length, pool width, shallow depth, and deep depth. It averages shallow and deep depth for a rectangular-prism estimate, then reports cubic feet, U.S. gallons, and liters.

Formula used

Average depth = (shallow depth + deep depth) ÷ 2; gallons = length × width × average depth × 7.48052

Pool Volume Calculator measurement plan showing Pool length feet, Pool width feet, Shallow depth feet

Worked pool volume example

Pool Volume Calculator example: Average depth = (3 ft + 6 ft) ÷ 2 = 4.5 ft. Then 24.6 × 14 × 4.5 = 1,549.8 ft³, or about 11,593 U.S. gallons.

Interpret gallons and flow

Use the gallons as a planning figure and confirm the pool builder's stated capacity before chemical dosing or equipment selection.

System effects the formula omits

Breaks in slope, a diving well, steps, benches, curves, freeboard, and nonrectangular plans can make a simple average-depth prism inaccurate.

Questions specific to this calculation

When is average depth a reasonable pool approximation?

Enter inside waterline length and width plus shallow and deep water depths; the tool uses their arithmetic mean as average depth.