Pool Volume Calculator
Measure your pool, pick its shape and get the gallons. Every chemical amount on this site depends on this number, so it's worth getting right.
Quick answer: A 16 × 32 ft rectangular pool that slopes from 3.5 ft to 6 ft deep holds about 18,190 gallons. A 24 ft round pool 4 ft deep holds about 13,540 gallons.
Checked against 4 published sources (see them). Updated October 2026.
- Average depth
- 4.75 ft
- Surface area
- 512.0 sq ft
- Water volume
- 2,432.0 cubic feet
Common pool sizes
Rectangle pools with a 3.5 ft shallow end and 6 ft deep end.
| Pool size | Gallons |
|---|---|
| 12 × 24 ft | 10,230 gallons |
| 14 × 28 ft | 13,930 gallons |
| 16 × 32 ft | 18,190 gallons |
| 18 × 36 ft | 23,030 gallons |
| 20 × 40 ft | 28,430 gallons |
How it works
Volume is the pool's surface area times its average depth. A rectangle's area is length × width. A round pool's is π × radius². An oval's is π × half the length × half the width. A kidney's is estimated as (big-end width + small-end width) × length × 0.45, the standard approximation published by the Pool & Hot Tub Alliance.
If the floor slopes steadily from shallow to deep, the average depth is halfway between the two. A pool with a sharp drop-off or a big deep-end hopper holds a little more or less than this estimate.
Cubic feet become gallons at 7.48 gallons per cubic foot. That comes from the legal definition of a US gallon: exactly 231 cubic inches, and a cubic foot is 1,728 cubic inches. One US gallon is exactly 3.785411784 liters.
Tips
- Measure water depth, not wall height. Most pools are filled a few inches below the top.
- Round to the nearest few hundred gallons. Chemical doses don't need more precision than that.
- Save the number. Every other calculator here asks for it.
Sources
We checked the math on this page against:
- NIST Handbook 44, Appendix C: units of measurement
- NIST SP 811, Appendix B: conversion factors
- Pool & Hot Tub Alliance: Pool & Spa Management (2021), Appendix B
- Leslie's: Calculating pool volume
Frequently asked questions
How many gallons is a 16 × 32 pool?
It depends on depth. With a 3.5 ft shallow end and 6 ft deep end (4.75 ft average), a 16 × 32 ft rectangle holds about 18,190 gallons. Use the calculator with your own depths.
Why does my pool's manual say a different number?
Manuals often use wall height or round numbers. Your actual water level and depths decide the real volume.
Is 7.48 gallons per cubic foot exact?
It's rounded. The exact figure is 1,728 ÷ 231 = 7.4805… gallons per cubic foot. This calculator uses the exact value.