Pool Volume Calculator
Multiply Length × Width × Average Depth × Shape Factor to get your pool volume. A standard 12 ft × 24 ft pool at 5 ft depth holds 10,771 gallons. Use the calculator above for your exact result in seconds.
Average depth: 5.00 ft
Use average depth
Average Depth = (Shallow + Deep) ÷ 2. Never use only the deep end — that is the most common mistake and overestimates volume.
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Select your pool shape, enter dimensions and depths, then click Calculate volume.
Pool measurement tips
- Measure inside wall to inside wall at the waterline, not outside the pool shell.
- For kidney pools, enter the wider and narrower width at the belly of the curve.
- Round pools: enter full diameter — the calculator converts to radius automatically.
- Split irregular pools into two rectangles and add both volumes together.
- Confirm US vs UK gallons on chemical labels (1 US gal = 3.785 L, 1 UK gal = 4.546 L).
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How to Use the Pool Volume Calculator
Follow these five steps to get your exact pool water capacity:
Step 1 — Select Your Pool Shape
Choose rectangular, round/circular, oval, or kidney-shaped. The pool calculator volume formula changes based on your pool's shape.
Step 2 — Enter Your Pool Dimensions
Use the pool dimension calculator fields to enter length and width in feet or metres. For round pools, enter the diameter only. For kidney pools, enter both the longer and shorter width measurements.
Step 3 — Enter Your Shallow and Deep End Depths
The pool measurement calculator automatically computes your average depth. Never enter the deep end only — this is the most common mistake pool owners make.
Step 4 — Choose Your Output Unit
Select US gallons, litres, or cubic metres (m³). The swimming pool volume calculator shows all three units at once so you never need to convert manually.
Step 5 — Click Calculate
Your pool water capacity calculator result appears instantly including gallons, litres, m³, and UK gallons for metric users.
Pro Tip
Average Depth = (Shallow End Depth + Deep End Depth) ÷ 2. A pool with a 3 ft shallow end and 8 ft deep end has a 5.5 ft average depth — not 8 ft. Always use average depth for accurate results.
Which Shape Is Your Pool?
The pool size pool volume calculator uses a different formula for each pool shape. Identify your pool type below before you start calculating.
| Pool Shape | Description | Best For |
|---|---|---|
| Rectangular | Straight edges, four right angles | Standard inground & lap pools |
| Round / Circular | Perfect circle shape | Most above-ground pools |
| Oval | Elongated round shape | Above-ground oval designs |
| Kidney / Freeform | Curved, irregular inground shape | Decorative inground pools |
Irregular or custom shape? Split your pool into two separate rectangular sections. Use the pool fill calculator for each section individually, then add both results together for the total swimming pool volume.
Pool Volume Formulas
Rectangular Pool Volume Formula
The most commonly used formula in the pool volume calculator:
Volume (gallons) = Length × Width × Average Depth × 7.48
Volume (litres) = Length × Width × Average Depth × 28.32
Volume (m³) = Length(m) × Width(m) × Average Depth(m)
Example: 12 ft × 24 ft × 5 ft average depth × 7.48 = 10,771 US gallons
Round Pool Volume Formula
Use the round pool volume calculator or circle pool volume calculator for above-ground circular pools:
Volume (gallons) = π × Radius² × Average Depth × 7.48
Radius = Diameter ÷ 2
Example: 15 ft diameter pool, 4 ft deep → π × 7.5² × 4 × 7.48 = 5,278 gallons
The pool volume calculator round and pool diameter calculator both use this formula. Enter your pool's full diameter — the calculator converts it to radius automatically.
Oval Pool Volume Formula
Use the volume of a pool calculator set to oval shape:
Volume (gallons) = π × (Length ÷ 2) × (Width ÷ 2) × Average Depth × 7.48
Example: 16 ft × 10 ft oval pool, 4 ft deep → π × 8 × 5 × 4 × 7.48 = 3,748 gallons
Kidney Pool Volume Formula
The pool volume calculator kidney uses the 0.45 shape correction factor for curves:
Volume (gallons) = (Wider Width + Narrower Width) × Length × 0.45 × Average Depth × 7.48
The 0.45 multiplier accounts for the volume lost in the kidney's curved indentation. Without it, the water pool calculator would significantly overestimate actual water capacity.
Pool Volume Calculator in Litres & m³
Users in the UK, Australia, Canada, and Europe calculate pool volume in litres and m³ by default. The pool volume calculator m3 mode handles all metric conversions automatically.
Countries using metric pool volume: 🇬🇧 United Kingdom | 🇦🇺 Australia | 🇨🇦 Canada | 🇩🇪 Germany | 🇫🇷 France | 🇮🇳 India | 🇳🇿 New Zealand
| Pool Shape | Formula (m³) | To Get Litres |
|---|---|---|
| Rectangular | L × W × Avg Depth | m³ × 1,000 |
| Round | π × r² × Avg Depth | m³ × 1,000 |
| Oval | π × (L/2) × (W/2) × Avg Depth | m³ × 1,000 |
| Kidney | (W1 + W2) × L × 0.45 × Avg Depth | m³ × 1,000 |
Measure all dimensions in metres when using the metric water calculator for pool mode. The volume calculator pool result in m³ multiplied by 1,000 gives you exact litres.
UK vs US Gallons: 1 UK gallon = 4.546 litres. 1 US gallon = 3.785 litres. Always confirm which gallon system your pool chemical labels use — the wrong unit can cause serious over or under-dosing.
Pool Volume by Common Pool Sizes
Use this table for a fast pool water capacity estimate. For precise results, always use the gallon in pool calculator above.
| Pool Size (ft) | Shape | Avg Depth (ft) | US Gallons | Litres | m³ |
|---|---|---|---|---|---|
| 12 × 24 | Rectangular | 4.5 | 9,700 | 36,700 | 36.7 |
| 16 × 32 | Rectangular | 5 | 19,200 | 72,700 | 72.7 |
| 18 × 36 | Rectangular | 5.5 | 26,900 | 101,800 | 101.8 |
| 20 × 40 | Rectangular | 5.5 | 33,000 | 124,900 | 124.9 |
| 15 ft dia. | Round | 4 | 5,300 | 20,070 | 20.1 |
| 18 ft dia. | Round | 4 | 7,640 | 28,900 | 28.9 |
| 24 ft dia. | Round | 4.5 | 15,300 | 57,900 | 57.9 |
| 16 × 32 | Oval | 4.5 | 15,100 | 57,100 | 57.1 |
| 20 × 16 | Kidney | 5 | 13,500 | 51,100 | 51.1 |
Why Knowing Your Pool Volume Matters
Accurate pool water capacity directly affects every area of pool ownership:
Chemical Dosing
Chlorine, pH adjusters, and shock treatments are dosed per gallon or litre. Wrong volume = unsafe or over-treated water.
Pump & Filter Sizing
Your pump must turn over full pool volume every 6–8 hours. Wrong volume = wrong pump size = cloudy water.
Heater Efficiency
Heater BTU ratings depend on total water volume. Underestimate and your heater runs non-stop without hitting target temperature.
Water Change Scheduling
Professionals recommend replacing 30–50% of pool water every 2–3 years. You need accurate volume to plan this correctly.
Winterizing & Closing
Antifreeze and closing chemicals require exact pool volume in gallons or litres. Approximate numbers waste money and damage equipment.
Permits & HOA Compliance
Many local building codes require you to declare pool water volume during inspections and permit renewals.
Common Mistakes When Using a Pool Volume Calculator
Mistake 1 — Using Deep End Depth Only
The most common error. A pool that is 3 ft shallow and 8 ft deep does NOT have an 8 ft depth. Average depth = (3 + 8) ÷ 2 = 5.5 ft. Every pool measurement calculator should use average depth, not the maximum.
Mistake 2 — Measuring Outside the Pool Walls
Pool shell thickness reduces internal water volume. Measure inside wall to inside wall at the waterline. Outside measurements overestimate actual capacity by 5–10%.
Mistake 3 — Using Rectangular Formula for Kidney Pools
Applying the rectangular formula to a kidney or freeform pool overestimates water volume by 10–15%. Always use the correct pool volume calculator kidney formula with the 0.45 shape factor.
Mistake 4 — Mixing Imperial and Metric Units
Entering length in feet but depth in metres produces a completely wrong result. The pool dimension calculator requires all inputs in the same unit system. Switch to metric mode if you work in metres.
Mistake 5 — Ignoring Steps, Ledges, and Attached Spas
Tanning ledges, entry steps, and spa attachments each hold water that affects your total chemical dosing. Calculate the main pool body first, then add or subtract attached features separately using the pool size pool volume calculator.
Frequently Asked Questions
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