How many gallons is my pool?
Enter your pool shape, dimensions, and the shallow and deep end depths. The calculator gives you the volume in US gallons and litres instantly — no sign-up needed.
Sloped floor detected — using average depth of 4.00 ft.
A rectangle pool 12 × 24 ft with a sloped floor (3–5 ft, avg 4.00 ft) holds 8,618 US gal.
Volume = length × width × avg depth. Avg depth = (shallow + deep) ÷ 2. Capacities use exact conversions (1 US gal = 3.785 L). This is pure geometry — not a code value or a product spec.
Pool volume reference table
Common rectangular pool sizes with a typical sloped floor. Enter your own dimensions for an exact figure.
| Pool size (ft) | Avg depth | US gallons | Litres |
|---|---|---|---|
| 10 × 20 ft | 3.5 ft | 5,236 | 19,822 |
| 12 × 24 ft | 4 ft | 8,618 | 32,621 |
| 14 × 28 ft | 4 ft | 11,729 | 44,401 |
| 16 × 32 ft | 4.5 ft | 17,235 | 65,242 |
| 18 × 36 ft | 5 ft | 24,237 | 91,747 |
| 20 × 40 ft | 5 ft | 29,922 | 113,267 |
All figures assume a sloped floor with the average of the shallow and deep end depths shown. Use the calculator for your exact dimensions.
Pool volume formulas
| Shape | Formula (cubic metres / feet) |
|---|---|
| Rectangle | L × W × avg depth |
| Round | π × (diameter ÷ 2)² × avg depth |
| Oval | π/4 × L × W × avg depth |
| Kidney (approx.) | 0.45 × (W1 + W2) × L × avg depth |
Avg depth = (shallow end + deep end) ÷ 2. For a flat-floor pool, enter the same value for both ends. The kidney formula is the standard industry approximation — labelled as approximate above.
Want the full working? Read the pool volume guide →
Common questions
- How do I calculate the volume of my pool in gallons?
- Measure the length, width and average depth, then use the formula for your pool shape. For a rectangular pool: gallons = length (ft) × width (ft) × average depth (ft) × 7.48. For example, a 12 × 24 ft pool with a 4 ft average depth is 12 × 24 × 4 × 7.48 = about 8,618 US gallons. The calculator above handles all four shapes — rectangle, round, oval and kidney — and does the conversion for you.
- How do I calculate the volume of a round pool?
- Volume = π × (diameter ÷ 2)² × average depth, then multiply by 7.48052 for US gallons. A round pool 14 ft across and 4 ft deep: π × 7² × 4 = 615.75 ft³ × 7.48052 = about 4,606 US gallons (17,436 litres). In metric: a round pool 4.27 m across and 1.22 m deep = π × 2.135² × 1.22 = about 17.5 m³ = 17,480 L.
- What is the formula for a kidney-shaped pool?
- Volume ≈ 0.45 × (W1 + W2) × length × average depth, where W1 is the narrower width and W2 is the wider width. The 0.45 factor is the standard industry approximation for a kidney outline — it is not exact, but it is the accepted method for estimating a kidney pool's volume.
- How many gallons is a 12×24 pool?
- A 12 × 24 ft rectangular pool with a 4 ft average depth (e.g., 3 ft shallow end and 5 ft deep end) holds about 8,618 US gallons (32,621 litres). If the average depth is different — say 3.5 ft — enter your own depths into the calculator for the exact figure.
- Why do I need to know my pool volume?
- Pool volume drives the chemical dosing amounts for chlorine, pH adjusters, algaecides and shock treatments. It also tells you how long your pump needs to run to turn the water over (typically at least once every 6–8 hours), and helps size a heater or heat pump for your pool.
Reference & education only. Not professional, engineering, or code-compliance advice. Estimates are based on published model codes; local amendments and your Authority Having Jurisdiction (AHJ) govern. Always verify against the current adopted code and a licensed professional before doing work.
Last reviewed 2026-07.