Home › Roofing & Outdoor › Pool Volume Calculator
This pool volume calculator tells you how many gallons or liters of water your swimming pool holds. It works for rectangular, round and oval pools with a constant depth or a shallow and deep end. Knowing the volume is essential for dosing chemicals correctly, sizing pumps and heaters, and estimating the cost of filling the pool.
How to Use the Pool Volume Calculator
- Choose the shape of your pool.
- Enter the length and width, or the diameter for a round pool.
- Enter the shallow and deep end depths. For a constant depth, enter the same number twice.
- Read the volume in US gallons, liters, cubic feet and cubic meters.
Pool Volume Formulas
| Shape | Volume (cubic feet) |
|---|---|
| Rectangular | Length × Width × Average depth |
| Round | π × (Diameter ÷ 2)² × Average depth |
| Oval | π × (Length ÷ 2) × (Width ÷ 2) × Average depth |
Average depth = (Shallow depth + Deep depth) ÷ 2
Gallons = Cubic feet × 7.48
Worked Example
A rectangular pool 32 × 16 ft that slopes from 3.5 ft to 8 ft has an average depth of 5.75 ft. 32 × 16 × 5.75 = 2,944 cubic feet. 2,944 × 7.48 = about 22,000 gallons (83,400 liters).
Typical Pool Volumes
| Pool | Approximate volume |
|---|---|
| Round above-ground 15 ft, 4 ft deep | 5,288 gal |
| Round above-ground 18 ft, 4 ft deep | 7,614 gal |
| Round above-ground 24 ft, 4 ft deep | 13,536 gal |
| Rectangular 16 × 32 ft, 3.5–8 ft deep | 22,000 gal |
| Rectangular 20 × 40 ft, 3.5–8 ft deep | 34,410 gal |
Why Pool Volume Matters
- Chemical dosing: chlorine, pH adjusters and shock are dosed per 10,000 gallons.
- Pump and filter sizing: most pools should turn over their full volume about once every 8 hours.
- Heating: heater size and running cost depend on the volume of water.
- Filling cost: multiply gallons by your water rate, usually quoted per 1,000 gallons.
Planning a patio around the pool? Use the paver calculator or the concrete calculator.
Frequently Asked Questions
How do I calculate pool gallons?
Multiply length × width × average depth in feet to get cubic feet, then multiply by 7.48 to get US gallons.
How many gallons is a 24 ft round pool?
A 24 ft round pool filled to 4 ft deep holds about 13,500 gallons.
How many liters are in a gallon?
One US gallon is about 3.785 liters, and one cubic meter is 1,000 liters.
Should I use the wall height or the water depth?
Use the actual water depth. Pools are usually filled a few inches below the top of the wall.
Related Calculators
Browse all roofing & outdoor calculators or see every tool on our home page.