Pool Volume Calculator
Find how much water your swimming pool holds in litres, gallons and m³, for any shape, with a shallow and deep end or a sloped floor.
Split the L into two rectangles that don’t overlap.
From your pool plans, or add up simpler shapes.
Measure to the water line, not the top of the wall.
Length of floor at the shallow depth before it slopes.
Length of floor at the full deep depth.
Time a bucket: litres ÷ seconds × 60 = L/min.
From the pump label or manual, at your system’s pressure.
Many home pools aim for 6–8 hours; check your local code.
From your water bill. Leave blank to skip.
These tariffs charge more per m³ as the month’s use goes up, so the fill costs more on top of normal use.
Type the dose printed on your product’s label. This only scales it to your pool’s size; it does not suggest a dose.
How your pool volume is worked out
Surface area × average depth = volume, then into litres and gallons.
- 1
Surface area
10 × 5 m= 50 m²
- 2
Average depth
(1 + 2) ÷ 2= 1.5 m
- 3
Area × depth
50 × 1.5= 75 m³
- 4
Litres and gallons
75 × 1,000= 75,000 L= 19,813 US gal
Read more: the formula for every shape, a worked example and handy figures
A pool’s volume is its surface area (the water you see from above) times its average depth. Work it out in metres to get cubic metres, then times 1,000 for litres; or in feet to get cubic feet, then times 7.48 for US gallons.
The formula
rectangle area = length × width
round area = π × (diameter ÷ 2)²
oval area = π ÷ 4 × length × width
kidney area ≈ (width A + width B) × 0.45 × length (an approximation)
L-shape area = part 1 length × width + part 2 length × width
average depth = (shallow end + deep end) ÷ 2
sloped floor: average depth = (shallow × flat shallow part + (shallow + deep) ÷ 2 × slope part + deep × flat deep part) ÷ pool length
volume = surface area × average depth
litres = m³ × 1,000 · US gallons = litres ÷ 3.785411784 · UK gallons = litres ÷ 4.54609 · US gallons = cu ft × 7.48052
water weight ≈ 1 kg per litre
time to fill = volume ÷ hose flow · turnover = volume ÷ pump flow · flow needed = volume ÷ target hours
product for your pool = label dose × (your volume ÷ the label’s volume)
Worked example
A rectangular pool 10 m long and 5 m wide, 1 m deep at the shallow end and 2 m at the deep end. The surface area is 10 × 5 = 50 m². The average depth is (1 + 2) ÷ 2 = 1.5 m. The volume is 50 × 1.5 = 75 m³, which is 75 × 1,000 = 75,000 litres, 75,000 ÷ 3.785411784 = 19,812.9 US gallons or 75,000 ÷ 4.54609 = 16,497.7 UK gallons. The water weighs about 75 tonnes (165,347 lb). With a hose giving 30 L/min it takes 75,000 ÷ 30 = 2,500 minutes, 41 hours 40 minutes, to fill. A 12 m³/h pump turns it over in 75 ÷ 12 = 6.25 hours; for an 8-hour turnover you need at least 75 ÷ 8 = 9.375 m³/h.
Sloped floor example
The same pool with 3 m of flat floor at 1 m deep, then a 5 m slope, then 2 m of flat floor at 2 m deep: (1 × 3 + 1.5 × 5 + 2 × 2) ÷ 10 = 14.5 ÷ 10 = 1.45 m average, so 50 × 1.45 = 72.5 m³ (72,500 litres). For a rectangle this is exact; for other shapes it is a close estimate.
Handy figures
| Unit | Litres | US gallons | UK gallons |
|---|---|---|---|
| 1 m³ | 1,000 | 264.172 | 219.969 |
| 1 cu ft | 28.317 | 7.481 | 6.229 |
| 1 US gallon | 3.785 | 1 | 0.833 |
| 1 UK gallon | 4.546 | 1.201 | 1 |
Gulf water prices used
| Preset | Water price |
|---|---|
| Qatar · Kahramaa, flat or villa | QAR 5.5 per m³ up to 20 m³ a month, 7 up to 250, then 10 |
| Dubai · DEWA, home | AED 7.7 per m³ up to 27 m³ a month, 8.8 up to 54, then 10.12; plus fuel surcharge AED 1.1 per m³ (October 2026) and 5% VAT |
| Bahrain · EWA, Bahraini one home | 25 fils per m³ up to 60 m³ a month, 80 up to 100, then 775 |
| Bahrain · EWA, others | 775 fils (BHD 0.775) per m³ |
| Oman · Nama Dhofar, home | OMR 0.66 per m³ |
From each supplier’s official tariff page, checked on 2026-10-13; the same figures as our Gulf bill calculators. Filling a pool may be charged differently, need a permit or be supplied by tanker; ask your supplier. Elsewhere, use your own price from your water bill.
Tips
- Measure depth to where the water sits, usually a little below the top of the wall or halfway up the skimmer opening.
- For odd shapes, split the pool into rectangles and circles, work out each area and add them, then use Freeform.
- Always follow the dose and safety directions on your chemical product’s label. The chemical box here only scales the label’s own figure to your pool size.
Common questions
How do I work out how many litres are in my pool?
Multiply the surface area by the average depth to get cubic metres, then multiply by 1,000 for litres. A pool 10 m by 5 m with a shallow end of 1 m and a deep end of 2 m has an average depth of 1.5 m, so it holds 10 × 5 × 1.5 = 75 m³, which is 75,000 litres.
How many gallons are in my pool?
In feet, multiply length × width × average depth to get cubic feet, then multiply by 7.48 for US gallons. A 32 × 16 ft pool, 3.5 ft to 8 ft deep (average 5.75 ft), holds 32 × 16 × 5.75 = 2,944 cu ft, or about 22,023 US gallons. From litres, divide by 3.785 for US gallons or by 4.546 for UK (imperial) gallons.
How do I measure a kidney-shaped pool?
Measure the length, the width across the wide end (A) and the width across the narrow end (B). A common rule of thumb is area ≈ (A + B) × 0.45 × length. It is an approximation: kidney pools vary, so if you have the area from the pool plans, pick Freeform and type it in.
How long will it take to fill my pool?
Divide the volume by your hose’s flow rate. 75,000 litres at 30 litres a minute takes 2,500 minutes, about 41 hours 40 minutes. To find your flow, time how long a bucket of known size takes to fill: litres ÷ seconds × 60 = litres per minute.
What is pool turnover?
Turnover is how long the pump takes to push the whole pool’s volume through the filter once: volume ÷ pump flow. 75 m³ with a 12 m³/h pump is 6.25 hours. Many home pools aim for a full turnover in roughly 6 to 8 hours; your local code or pool builder may set a different figure.
How much does a pool’s water weigh?
Fresh water weighs about 1 kg per litre, so a 75,000 litre pool holds about 75 tonnes of water (about 165,000 lb). Salt water pools are only slightly heavier.
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Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.