Pool Size Calculator
Choose your pool shape and enter the length, width and the depths at the shallow and deep ends. The calculator gives the volume, surface area, the pump flow you need and a starting chemical dose.
- Litres and gallons
- Sloped floors handled
- Pump and chemical sizing
Measure inside the pool, at the water line. For a round pool, enter the diameter as the length.
Everything in pool care starts with the volume. Chemical doses, pump size, heater size and fill time all depend on how much water the pool holds. A pool with a sloping floor holds about the same as a flat one at the average of the shallow and deep ends.
Common pool volumes
Typical pools and what they hold. Search for a size.
| Pool | Size | Avg depth | Litres | US gallons |
|---|---|---|---|---|
| Round above-ground | 3.66 m (12 ft) | 0.9 m | 9470 | 2500 |
| Round above-ground | 4.57 m (15 ft) | 1.1 m | 18050 | 4770 |
| Round above-ground | 5.49 m (18 ft) | 1.2 m | 28400 | 7500 |
| Plunge pool | 4 × 2 m | 1.4 m | 11200 | 2960 |
| Small in-ground | 8 × 4 m | 1.5 m | 48000 | 12680 |
| Family in-ground | 10 × 5 m | 1.5 m | 75000 | 19810 |
| Large in-ground | 12 × 6 m | 1.6 m | 115200 | 30430 |
| Lap pool | 20 × 3 m | 1.3 m | 78000 | 20600 |
Above-ground pools are usually filled to about 15 cm below the top rail, so the real volume is a little less than the shell size.
Average depth and volume
An 8 × 4 m pool. Slide the average depth.
A 20 L/min garden hose fills an 8 by 4 m, 1.5 m deep pool in about 40 hours. Plan the fill over a weekend.
How to work out pool volume
Surface area times average depth. Step through it.
Pick the shape
Rectangle, round, oval or free-form.
One cubic metre of water is 1,000 litres and weighs one tonne. A small pool holds the weight of dozens of cars.
Above-ground, in-ground or plunge
Three common pool types. Compare them.
Quick to install and move. Usually round with one depth.
Permanent, often with a shallow and deep end.
Small and deep for cooling off and exercise in tight spaces.
Smaller pools heat faster and cost less to run, but the water chemistry swings more quickly, so test more often.
Opening the pool
Start of season checks. Tick each item.
Tick each item as you go.
Keep free chlorine at 1 to 3 ppm and pH at 7.2 to 7.6. Most water problems start with pH drifting out of range.
What the result shows
Numbers for your pool shop. Each tile explains one result.
Litres, gallons and m³.
For covers and heating.
Between the two ends.
To turn over the water in 8 hours.
A starting amount of chlorine.
Pool shops ask for the volume to work out every dose, so keep the figure handy.
Frequently Asked Questions
No question matches that search.
How do I calculate pool volume?
Multiply surface area by average depth to get cubic metres, then multiply by 1,000 for litres.
How many litres in an 8 by 4 metre pool?
At an average depth of 1.5 m, about 48,000 litres.
How many gallons in a 15 ft round pool?
About 4,770 US gallons when filled to about 1.1 m (3.6 ft) deep.
How do I measure a pool with a sloping floor?
Measure the shallow and deep ends and use their average.
How big a pump does my pool need?
One that can move the whole volume in about 8 hours. A 48,000 L pool needs about 6,000 L/h.
How long does it take to fill a pool?
Litres ÷ hose flow. A 48,000 L pool takes about 40 hours at 20 L/min.
How much chlorine do I need?
It depends on the product. For shock, about 15 g of 65% calcium hypochlorite per 1,000 L raises chlorine by 10 ppm.
Know your pool's volume
Pick the shape, average the depth and multiply. With the volume in hand you can size the pump, dose chemicals accurately and plan the fill with no guesswork.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.