Swimming Pool Water Fill Calculator
Work out how many litres or kilolitres it takes to fill a rectangular or round pool.
How much does it cost to fill a swimming pool?
- Cost = pool volume in kilolitres (kL) × your water price per kL. 1 kL is 1,000 litres.
- Find your price per kL on a recent water bill. Prices vary by city and retailer, and some bills use tiered rates, so the last kilolitres can cost more than the first.
- Enter your water price in the optional field below and the calculator adds the cost to the volume.
Result
46,400 litres (46.4 kL)
- Surface area
- 32 m²
- Average depth
- 1.45 m
- Volume (litres)
- 46,400 L
- Volume (kilolitres)
- 46.4 kL
Volume is surface area multiplied by average depth. 1 cubic metre of water equals 1,000 litres, or 1 kilolitre.
How it's calculated
- Rectangular pool: surface area = length × width. Round pool: surface area = π × (diameter ÷ 2)².
- Average depth = (shallow end depth + deep end depth) ÷ 2.
- Volume in kilolitres = surface area × average depth. Multiply by 1,000 for litres.
- Fill cost = kilolitres × your water price per kL.
Worked examples
An 8 m × 4 m pool, 1.1 m to 1.8 m deep
Area = 8 × 4 = 32 m². Average depth = (1.1 + 1.8) ÷ 2 = 1.45 m. Volume = 32 × 1.45 = 46.4 kL, or 46,400 litres. At an illustrative $3.00 per kL (use the rate on your own bill) that is 46.4 × 3 = $139.20.
A round pool, 5 m across, 1.1 m to 1.8 m deep
Area = π × 2.5² = 19.63 m². Volume = 19.63 × 1.45 = about 28.5 kL, or roughly 28,470 litres.
Assumptions and notes
- Assumes a consistent cross-section from shallow to deep end — a straight-line average of the two depths.
- For an irregular-shaped pool, measure or estimate the closest equivalent rectangle or circle, or get a figure from your pool builder.
- Water pricing varies by state, retailer and usage tier — enter your own rate from a recent water bill for a cost estimate.
Information last checked: August 2026.
Frequently asked questions
How many litres are in a cubic metre?
1 cubic metre (1 m × 1 m × 1 m) holds 1,000 litres, which is the same as 1 kilolitre (kL).
What if my pool has a constant depth?
Enter the same value for both the shallow end and deep end depth fields — the average will simply be that depth.
How do I work out the cost of filling a swimming pool?
Multiply the volume in kilolitres by your water price per kL, which is on your water bill. The calculator does this when you enter a price.
Should I measure the depth to the top of the pool?
No. Measure the depths to the water level you normally run the pool at, which is usually a little below the top, because the calculator assumes the pool is filled to the depths you enter.