Filling
Type feet and inches like 3'6" or just 3.5. Measure the depth of the water, not the wall. For a pool with a spa, add the spa as a second pool. Everything is saved on this device.
About the pool volume calculator
This free pool volume calculator tells you how many gallons (or litres) of water are in your swimming pool. Pick the shape — rectangle, round, oval, ellipse or kidney — and type the size and the depth of the water. If the floor slopes, type the shallow end and the deep end: the tool uses the average depth.
You also get the cubic feet, the weight of the water, the water surface and how many hours a garden hose needs to fill the pool. Add a spa or a second pool and the tool adds them up.
Features
- Gallons and litres — plus cubic feet (or m³) and the weight of the water
- 5 pool shapes — rectangle, round, oval with round ends, true ellipse and kidney
- Shallow and deep end — the average depth for a sloped floor, or one depth for a flat one
- Fill time — hours to fill with a hose, from a flow you can change
- Pool + spa — add more pools and get each one and the total
- Feet or metres — litres and m³ in metric
- No chemical doses — just the volume, to use with the dose on each product's label
- Saved on this device — your pool size is still here next time
How pool volume is worked out
Volume = water surface × average depth. One cubic foot holds 7.48 US gallons, and one m³ is 1,000 litres.
| Shape | Water surface |
|---|---|
| Rectangle | length × width |
| Round | 0.785 × diameter × diameter |
| Oval with straight sides and round ends | (length − width) × width + 0.785 × width × width |
| Ellipse (a true oval) | 0.785 × length × width |
| Kidney | 0.45 × (width at the big end + width at the small end) × length |
Average depth = (shallow end + deep end) ÷ 2. This assumes the floor slopes evenly from one end to the other. A pool with a steep deep-end hopper holds a little less than this.
The kidney formula is the usual pool-trade estimate. Kidney pools differ, so treat it as a close guess.
Gallons in common above-ground pools
With 48 in (4 ft) of water:
| Round pool | Gallons | Litres |
|---|---|---|
| 12 ft | 3,384 | 12,810 |
| 15 ft | 5,288 | 20,016 |
| 18 ft | 7,614 | 28,823 |
| 21 ft | 10,364 | 39,231 |
| 24 ft | 13,536 | 51,241 |
| 27 ft | 17,132 | 64,852 |
| Oval pool (round ends) | Gallons | Litres |
|---|---|---|
| 12 × 24 ft | 7,693 | 29,121 |
| 15 × 24 ft | 9,327 | 35,307 |
| 15 × 30 ft | 12,020 | 45,501 |
| 18 × 33 ft | 15,693 | 59,405 |
Above-ground oval pools have straight sides and round ends. A true ellipse of the same size holds about 12% less, so pick the right shape.
Worked examples
- In-ground rectangle, 16 × 32 ft, 3 ft 6 in to 8 ft deep: average depth 5 ft 9 in; 16 × 32 × 5.75 = 2,944 cu ft = 22,023 gallons (83,365 L). The water weighs about 184,000 lb.
- Kidney pool, 30 ft long, 16 ft and 12 ft wide, 3 ft 6 in to 6 ft deep: 0.45 × 28 × 30 = 378 sq ft × 4.75 ft = 13,431 gallons.
- Spa, 7 × 7 ft, 3 ft deep: 1,100 gallons.
- Metric pool, 10 × 5 m, 1.2 to 2.4 m deep: 50 m² × 1.8 m = 90 m³ = 90,000 litres.
How long does it take to fill a pool?
A garden hose gives roughly 5 to 12 gallons a minute (about 20–45 L/min), depending on the hose and the water pressure. Time it: fill a 5-gallon bucket and count the seconds, then type your flow.
| Pool | 5 gal/min | 9 gal/min | 12 gal/min |
|---|---|---|---|
| 13,536 gal (24 ft round) | 45 hours | 25 hours | 19 hours |
| 20,000 gal | 67 hours | 37 hours | 28 hours |
For a big pool, a water truck can be faster. Ask your water company about the cost and any rules for filling a pool.
Frequently asked questions
How do I work out how many gallons are in my pool?
Multiply the length × width × average depth in feet to get cubic feet, then multiply by 7.48. A 16 × 32 ft pool with an average depth of 5.75 ft holds about 22,000 gallons.
How many gallons are in a 24 ft round pool?
About 13,536 gallons with 4 ft of water, and about 11,844 gallons with 3.5 ft. Check your own water depth: most pools are filled a few inches below the top.
How do I measure a pool with a deep end?
Measure the water depth at the shallow end and at the deep end, and type both. The tool takes the average. For a flat floor, leave the deep end empty.
How long does it take to fill a pool with a hose?
Divide the gallons by the hose flow per minute, then by 60. A 20,000-gallon pool at 9 gallons a minute takes about 37 hours.
Why do I need the pool volume?
Pool chemicals, heaters and covers are sold by pool size, and every product label gives its dose for a volume of water. This tool gives the volume only — follow the label for the dose.
Can I get the volume in litres?
Yes. Litres are always shown. Switch to Metres & cm to type the size in metres and get litres and m³ first.
Related tools
- Aquarium Volume Calculator — gallons and litres for a fish tank
- Gallons to Liters — convert any amount of water
- Square Footage Calculator — the area of the pool deck
- Paver Calculator — pavers for the area around the pool
- Concrete Calculator — a concrete pad or pool deck
How to use it
- Choose Feet & inches or Metres & cm
- Pick the shape of your pool
- Type the size: length and width, or the diameter for a round pool
- Type the water depth at the shallow end, and at the deep end if the floor slopes
- Add a spa or another pool with Add another pool or spa
- Check the hose flow for the fill time, and press Copy the list
