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Free Pool Volume Calculator (+ Guide)

A free pool volume calculator for rectangle, round and oval pools, in gallons and liters, with the time to fill.

Navid Moazzezby Navid Moazzez·Updated 3 ott 2026·2 min read·
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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.mdTL;DR

Key takeaways

A US gallon is 231 cubic inches (NIST), so a cubic foot is about 7.48 gallons.
A rectangle pool's volume is length × width × average depth.
A round pool uses π × (across ÷ 2)², and an oval π ÷ 4 × length × width.
A 32 by 16 foot pool, 3 to 8 feet deep, holds about 21,065 gallons.

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.

ShapeSurface area
RectangleLength × width
Roundπ × (across ÷ 2)²
Ovalπ ÷ 4 × length × width
Work out your pool's volume0/4

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.

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 Moazzez

AI business strategist & AI OS builder

Navid Moazzez helps creators and founders master AI and build their own AI Operating System (AI OS) to automate their business and life.

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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