How Many Litres in a Pool? Round, Oval and Rectangular (UK)
A pool holds its surface area times its average depth. A 6 × 3 m rectangular pool with water 1.0 m deep at one end and 1.6 m at the other has an average depth of 1.30 m, so it holds 23,400 litres (23.4 m³), and the water weighs about 23.4 tonnes. The pool volume calculator does the sum for your shape and depth.
Litres by pool size
At a flat water depth of 1.2 m:
| Pool | Litres | m³ | Weight of the water |
|---|---|---|---|
| Round, 3 m across | 8,482 | 8.5 | 8.5 tonnes |
| Round, 4 m across | 15,080 | 15.1 | 15.1 tonnes |
| Round, 5 m across | 23,562 | 23.6 | 23.6 tonnes |
| Rectangular, 4 × 2 m | 9,600 | 9.6 | 9.6 tonnes |
| Rectangular, 6 × 3 m | 21,600 | 21.6 | 21.6 tonnes |
| Rectangular, 8 × 4 m | 38,400 | 38.4 | 38.4 tonnes |
| Oval, 6 × 3 m | 16,965 | 17.0 | 17.0 tonnes |
| Oval, 8 × 4 m | 30,159 | 30.2 | 30.2 tonnes |
Litres by depth
The depth of the water changes the volume as much as the size does. A 4 m round pool, a 6 × 3 m rectangle and a 6 × 3 m oval, each with a flat floor:
| Water depth | Round, 4 m | Rectangular, 6 × 3 m | Oval, 6 × 3 m |
|---|---|---|---|
| 0.8 m | 10,053 litres | 14,400 litres | 11,310 litres |
| 1.0 m | 12,566 litres | 18,000 litres | 14,137 litres |
| 1.2 m | 15,080 litres | 21,600 litres | 16,965 litres |
| 1.5 m | 18,850 litres | 27,000 litres | 21,206 litres |
Measuring a pool
- Measure the water, not the pool wall: a pool filled to the skimmer is some centimetres lower than the rim.
- For a sloping floor, measure the depth at the shallow end and the deep end and use the average. If the floor has a deep middle, measure at several places.
- A rectangle with rounded corners is close to a rectangle: the corners take away only a little.
- An oval or round pool uses π ÷ 4 (0.7854) times the rectangle that would just contain it.
- For a freeform shape, split it into rectangles and circles, work out each, and add them.
Filling the pool
A hosepipe is slow. At three common flow rates, this pool takes:
| Hosepipe flow | Hours | Days |
|---|---|---|
| 10 litres a minute | 39 hours | 1.6 days |
| 20 litres a minute | 20 hours | 0.8 days |
| 30 litres a minute | 13 hours | 0.5 days |
Time a 10 litre bucket to find your flow: 10 divided by the seconds, times 60. During a hosepipe ban, water companies' notices say you cannot fill or top up a domestic pool with a hosepipe, with a limited exception for the first fill of a newly built fixed pool. Check your own water company's notice. Water from a bucket, a water butt or a private borehole is not covered, and some people have the water delivered.
Why the volume matters
- Chemicals are dosed per litre or per cubic metre, so a wrong volume gives a wrong dose.
- A litre of water weighs about 1 kg, so a pool of 23 m³ holds about 23 tonnes. Check that the ground and any base can carry it.
- Heaters, pumps and covers are sized from the volume or the surface area.
- It tells you how long a fill or a top up will take, and what it will cost on a water meter.
A water butt collects some of the water for free: see the water butt calculator. For a concrete base under an above-ground pool, use the concrete calculator. These are estimates: measure your own pool.
Frequently asked questions
How many litres are in a swimming pool?
Multiply the surface area by the average depth in metres and by 1,000. A 6 × 3 m pool with an average depth of 1.30 m holds 23,400 litres.
How many litres is a 4 m round pool?
At a flat water depth of 1.2 m, about 15,080 litres.
How do I work out the litres in an oval pool?
Length × width × 0.7854 for the surface area, times the average depth, times 1,000. A 6 × 3 m oval at 1.2 m deep holds 16,965 litres, against 21,600 for a rectangle of the same size.
How long does a hosepipe take to fill a pool?
It depends on the flow. This pool takes 20 hours at 20 litres a minute and 1.6 days at 10. Time a 10 litre bucket to find your own flow.
Can I fill a pool with a hosepipe in a hosepipe ban?
Usually not. Water company notices ban filling or topping up a domestic swimming or paddling pool with a hosepipe while the ban lasts, with a limited exception for the first fill of a newly built fixed pool. Check your water company's notice.
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and check the Building Regulations and any planning rules for anything structural or close to a boundary.
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