Tip: For sloped pools, average depth = (shallow end + deep end) ÷ 2.
How to use this pool litres calculator
Knowing your pool volume is one of the most important numbers in pool care. Whether you are balancing chlorine, adding salt, adjusting pH, or planning water replacement, everything starts with an accurate litre value.
This calculator helps you estimate water volume for three common pool shapes:
- Rectangular pools (most in-ground builds)
- Circular pools (many above-ground pools)
- Oval pools (popular family sizes)
Select the shape, choose metres or feet, enter your dimensions and average depth, then click Calculate Pool Litres.
Why pool volume in litres matters
If your volume estimate is off, your chemical dosing is off. A pool that is actually 45,000 litres but treated like 35,000 litres can drift out of range quickly. That leads to cloudy water, algae growth, poor sanitation, and unnecessary costs.
Key tasks that depend on volume
- Daily and weekly chlorine dosing
- Salt chlorinator setup and salinity correction
- Alkalinity and calcium hardness adjustment
- Shock treatment planning
- Pump run-time optimization
Pool litre formulas used in the calculator
1) Rectangular pool
Volume = Length × Width × Average Depth
When using metres, this gives cubic metres, then we convert: 1 m³ = 1,000 litres.
2) Circular pool
Volume = π × (Diameter ÷ 2)² × Average Depth
Round pools are common for above-ground setups, and this formula estimates the cylinder volume.
3) Oval pool
Volume = π × (Length ÷ 2) × (Width ÷ 2) × Average Depth
This models the surface area as an ellipse and then multiplies by depth.
Example calculations
Example A: Rectangular pool in metres
Length 8 m, width 4 m, average depth 1.5 m:
8 × 4 × 1.5 = 48 m³ → 48,000 litres.
Example B: Round pool in feet
Diameter 24 ft, average depth 4 ft:
π × 12² × 4 = 1,809.56 ft³.
Converted result is roughly 51,240 litres.
How to measure average depth correctly
For flat-bottom pools, average depth is just the actual depth. For sloped pools, calculate:
Average depth = (shallow depth + deep depth) ÷ 2
Example: shallow end 1.1 m, deep end 2.1 m:
(1.1 + 2.1) ÷ 2 = 1.6 m average depth
Common mistakes to avoid
- Using outside shell measurements instead of waterline dimensions
- Guessing depth rather than measuring shallow and deep ends
- Mixing metres and feet in one calculation
- Forgetting to recalculate after structural changes or resurfacing
Quick volume conversion references
- 1 cubic metre = 1,000 litres
- 1 cubic foot = 28.3168 litres
- 1 litre = 0.2642 US gallons
- 1 litre = 0.2200 imperial gallons
Final thoughts
A reliable pool litres estimate saves money, prevents overtreatment, and keeps water quality stable. Use this calculator whenever you set up a new pool routine or troubleshoot chemistry issues. Even a quick re-check of dimensions can make a big difference in maintenance accuracy over time.