Pool Volume Calculator
Convert your pool dimensions into gallons for dosing and heating.
What you'll need to order
- pool chemicals
- test kit
- pool heater
Prices vary by region and haul distance. Get quotes from at least two local suppliers.
How this calculator works
gallons = length × width × average depth × shape factor × 7.48
A cubic foot holds 7.48 US gallons. The shape factor approximates the area lost on curved pools — 0.85 for oval and kidney shapes, 0.79 for circular.
Switch the site to metric — the control is in the footer — and your inputs, your results and the tables below follow. The formula, the constants, the guidance text and the sources stay in US units on purpose: that is how the standards they come from are written, and restating them would detach each figure from the document you are meant to be able to check it against.
Where these numbers come from
- NIST Special Publication 811 2008 — the US gallon as 231 cubic inches, or 7.48 gallons per cubic foot
Standards are revised on a cycle. The edition above is the one this figure was checked against — confirm it against the edition your jurisdiction has adopted.
Worked example
With length 32 ft, width 16 ft, average depth 5 ft, shape factor 1 , this calculator returns 19150.13 gal.
Pool volume by average depth
Figures below assume length 32 ft × width 16 ft × shape factor 1 . Click through any row to load those measurements. The address bar keeps them, which makes the result something you can paste into a message.
| Average depth | Pool volume (gal) | Cubic feet (cu ft) |
|---|---|---|
| 3 ft | 11,490 | 1,536 |
| 3.5 ft | 13,405 | 1,792 |
| 4 ft | 15,320 | 2,048 |
| 4.5 ft | 17,235 | 2,304 |
| 5 ft | 19,150 | 2,560 |
| 6 ft | 22,980 | 3,072 |
| 8 ft | 30,640 | 4,096 |
A 32 by 16 ft rectangular pool. Average depth is what matters, not the deep end — add shallow and deep depths and halve them.
Volume of common pool sizes
Click through any row to load those measurements. The address bar keeps them, which makes the result something you can paste into a message.
| Job | Size | Pool volume |
|---|---|---|
| Above-ground round, 18 ft | 18 ft × 18 ft × 4 ft × 0.79 | 7,659 gal |
| Above-ground round, 24 ft | 24 ft × 24 ft × 4.5 ft × 0.79 | 15,318 gal |
| Small rectangular, 12x24 | 24 ft × 12 ft × 4.5 ft × 1 | 9,695 gal |
| Standard in-ground, 16x32 | 32 ft × 16 ft × 5 ft × 1 | 19,150 gal |
| Large in-ground, 20x40 | 40 ft × 20 ft × 5.5 ft × 1 | 32,914 gal |
| Kidney shape, 15x30 | 30 ft × 15 ft × 4.5 ft × 0.85 | 12,876 gal |
Shape factor corrects a rectangular estimate: 1 for a rectangle, 0.85 for kidney and oval shapes, 0.79 for a circle.
Shape factors
| Type | Multiplier | Notes |
|---|---|---|
| Rectangle or square | 1.00 | No correction needed |
| Oval | 0.89 | Length and width at the widest points |
| Kidney | 0.85 | Average the two widths first |
| Circle | 0.79 | Use the diameter for both dimensions |
| Free-form | 0.85 | A reasonable estimate; measure again if dosing matters |
Getting volume wrong is why pool chemistry goes wrong. Every dose on a chemical label is per 10,000 gallons, so a 20% volume error is a 20% dosing error, every time.
Frequently asked questions
How many gallons is a 16x32 pool?
About 19,000 gallons at an average depth of 5 feet. Multiply length by width by average depth to get cubic feet, then multiply by 7.48.
How do I calculate average pool depth?
Add the shallow end depth to the deep end depth and divide by two. For a pool with a long transition slope, measure at three points and average those instead.
How many gallons is a 24 foot round pool?
Roughly 13,500 gallons at 4.5 ft deep. Round pools use a 0.79 shape factor against the square of the diameter.
How many gallons is my pool?
Multiply length by width by average depth in feet, then by 7.48. A 32 by 16 ft pool averaging 5 ft deep holds about 19,150 gallons.
How do I find average depth?
Add the shallow end depth to the deep end depth and divide by two. For a pool with a long flat shallow section, weight it by the area at each depth instead — a simple average overstates volume.
Why does volume matter for pool chemicals?
Every dose is specified per 10,000 gallons. Getting the volume wrong by 20% means every chlorine, acid and stabiliser addition is wrong by the same margin, which is how pools end up chronically out of balance.
How many gallons in a cubic foot of water?
Just under 7.5 — precisely 7.48052 US gallons, weighing about 62.4 lb. That weight is worth remembering when calculating loads on a deck or structure.