How to use this pool volume calculator
- Choose the pool shape.
- Measure the length and width at the water line (the diameter for round pools).
- Measure the depth at the shallow and deep ends. For a flat-bottom pool, enter the same value twice.
Example
A 24 ft round above-ground pool filled to 4 ft of water holds about 13,536 gallons (51,241 L). That is the number to use when dosing chlorine, salt or any other chemical.
What to know before you buy
Why volume matters
Every pool chemical dose is based on the number of gallons. If you overestimate the volume you waste chemicals and can overshoot target levels; if you underestimate it the water stays unbalanced. Knowing your volume also helps size pumps, heaters and filters.
Pool size and turnover
A pool's filtration system should circulate the entire volume at least once per day. Divide the volume by the pump's gallons per hour to find how many hours it must run for one turnover.
Gallons in common pool sizes
| Pool | Pool volume | Liters |
|---|---|---|
| Round 15 ft, 4 ft deep | 5,288 gallons | 20,016 L |
| Round 18 ft, 4 ft deep | 7,614 gallons | 28,823 L |
| Round 24 ft, 4 ft deep | 13,536 gallons | 51,241 L |
| Oval 15 × 30 ft, 4 ft deep | 10,575 gallons | 40,032 L |
| Rectangle 16 × 32 ft, 3.5–6 ft | 18,193 gallons | 68,867 L |
| Rectangle 20 × 40 ft, 3.5–8 ft | 34,410 gallons | 130,257 L |
Formula
Rectangular: L × W × average depth. Round: π × radius² × average depth. Oval: π × (L ÷ 2) × (W ÷ 2) × average depth. 1 cubic foot = 7.48 US gallons.
Tips from the pros
- Measure depth to the water line, not the top of the wall.
- For irregular (kidney or freeform) pools, split the pool into rectangles and circles and add the volumes.
- Your water meter reading before and after filling gives the most accurate volume.
Common mistakes to avoid
- Using the wall height of an above-ground pool: the water is usually 6 inches lower.
- Averaging depth wrongly for pools with a long shallow area and a short deep end; split them into sections instead.
Frequently asked questions
How many gallons is a 24 ft round above ground pool?
About 13,500 gallons at 4 ft deep, or roughly 17,000 gallons at 52 inches of water.
Why does my pool volume matter?
Every chemical dose is based on volume. Overestimating wastes chemicals; underestimating leaves water unbalanced.
How many gallons is a 16x32 pool?
With a 3.5–6 ft depth, about 18,200 gallons.
How many gallons in a cubic foot of water?
7.48 US gallons, or about 28.3 liters.