A free pool volume calculator for rectangle, round and oval pools, in gallons and liters, with the time to fill.
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This free pool volume calculator works out how many gallons or liters your pool holds, for a rectangle, a round or an oval pool.
It takes a shallow and a deep end, and tells you how long the pool takes to fill at your hose's rate.
I built it because chemicals, heaters and pumps are all sized by the volume, and pools are rarely one depth.
Here's the formula for each shape, a worked example, and the mistakes to avoid.
Key takeaways
What is a pool volume calculator?
A pool volume calculator turns a pool's size and depth into the water it holds.
It works in gallons and liters, from feet or meters.
How pool volume works
The surface area × the average depth gives cubic feet. NIST Handbook 44 defines the gallon as 231 cubic inches, so 1 cubic foot is 1,728 ÷ 231 = 7.48 gallons.
| Shape | Surface area |
|---|---|
| Rectangle | Length × width |
| Round | π × (across ÷ 2)² |
| Oval | π ÷ 4 × length × width |
A worked example
Here's the example the calculator loads: a 32 by 16 foot pool, 3 feet at the shallow end and 8 at the deep end.
32 × 16 = 512 square feet. The average depth is 5.5 feet, so 512 × 5.5 = 2,816 cubic feet, or about 21,065 gallons (79,740 liters). At 10 gallons a minute, it fills in about 35 hours.
Mistakes to avoid
These are the slips that come up most.
- Taking the deep end's depth as the pool's depth
- Measuring the deck instead of the water
- Mixing up a round pool's distance across with its radius
Who is the pool volume calculator for?
It's for pool owners and anyone filling or treating a pool, and these tools help around it.
- Square footage calculator – for the deck around it
- Cubic yard calculator – for digging or filling
- Concrete calculator – for a pool deck slab
Know your gallons, and every dose and pump size starts from the right number.
Plan your money with your AI
Take your numbers further in
Pool Volume Calculator FAQs
Questions about the pool volume calculator? Here's what to know.
A pool volume calculator works out how many gallons or liters a pool holds.
Multiply the surface area by the average depth for cubic feet, then by 7.48.
About 7.48, since a US gallon is 231 cubic inches.
Add the shallow and deep ends and divide by 2.
About 13,536 gallons.
Divide the gallons by your fill rate in gallons a minute, then by 60 for hours.
Yes, switch to meters and the results show in liters.
Yes, it's free with no sign-up.
It runs in your browser, and your numbers stay on your device.
I did.
I'm Navid Moazzez, and I made the pool volume calculator as one of my free tools on navid.me.
More about me.
Navid.me is reader-supported. When you buy through links on this site, I may earn an affiliate commission. Learn more.
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