How do I calculate the volume of my swimming pool?

Volume depends on pool shape. Rectangular: Length × Width × Average Depth. Circular: π × radius² × Average Depth. Oval: π × (Length/2) × (Width/2) × Average Depth. Kidney-shaped: 0.45 × (Width A + Width B) × Length × Average Depth. Multiply the result in cubic metres by 1,000 to get litres, or by 264.172 to get US gallons.

How do I calculate average depth for a pool with a shallow and deep end?

For a pool with a sloping bottom, Average Depth = (Shallow End Depth + Deep End Depth) ÷ 2. For a pool with a flat bottom and sloped ends, use the formula: Average Depth = ((Shallow End × 0.33) + (Deep End × 0.67)). This calculator uses the simple average which is accurate enough for most residential pools.

How many gallons of water does a typical swimming pool hold?

A standard backyard rectangular pool (10m × 5m × 1.5m average depth) holds about 75,000 litres or roughly 20,000 US gallons. An above-ground round pool (4.5m diameter × 1.2m deep) holds about 19,000 litres or 5,000 US gallons. Volume varies enormously by size and shape.

Why do I need to know my pool volume?

Pool volume is essential for: (1) Calculating chemical doses — chlorine, algaecide, pH adjusters are all dosed per 1,000 litres or 1,000 gallons. (2) Estimating water cost and fill time from your mains supply. (3) Sizing your pump and filter — flow rate should turn over the pool volume every 6–8 hours. (4) Calculating heating costs.

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Pool Volume Calculator

Calculate the exact water volume of your swimming pool in litres and gallons. Supports rectangular, round, oval, kidney-shaped, and L-shaped pools — plus fill time and pump sizing estimates.

Pool Shape

Pool Dimensions

Units

Fill Time & Pump Sizing

Fill Rate (litres/hour)

Typical garden hose ≈ 1,000 L/hr; mains supply ≈ 2,000–5,000 L/hr

Pump Flow Rate (m³/hr)

Pool should turn over every 6–8 hours. Min pump = volume ÷ 7.

Results

Volume

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litres

US Gallons

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m³

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Fill Time (at set rate)

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Turnover (at pump rate)

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Min Pump Size Needed

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Chemical Dose Reference (per full volume)

Chlorine (initial shock)

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Algaecide

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pH adjuster (per unit)

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Always follow manufacturer instructions — these are approximate starting points only.

Typical Pool Sizes & Volumes

Pool Type	Dimensions	Volume (litres)	Volume (US gal)
Small plunge pool	3m × 2m × 1.2m	~7,200 L	~1,900 gal
Average backyard (rect)	8m × 4m × 1.4m avg	~44,800 L	~11,830 gal
Standard family pool	10m × 5m × 1.5m avg	~75,000 L	~19,810 gal
Large pool	15m × 6m × 1.6m avg	~144,000 L	~38,000 gal
Above-ground round (sm)	3.6m dia × 0.9m deep	~9,160 L	~2,420 gal
Above-ground round (lg)	5.5m dia × 1.2m deep	~28,500 L	~7,530 gal
Olympic pool	50m × 25m × 2m	2,500,000 L	~660,400 gal

Frequently Asked Questions

For rectangular pools: Volume = Length × Width × Average Depth. For round pools: Volume = π × (Diameter÷2)² × Depth. For oval pools: Volume = π × (L÷2) × (W÷2) × Depth. For kidney pools: Volume ≈ 0.45 × (Width A + Width B) × Length × Depth. Multiply m³ by 1,000 to get litres, or by 264.172 for US gallons.

For a pool with a gradual slope from shallow to deep end, the average depth = (shallow end depth + deep end depth) ÷ 2. For example, a pool going from 0.9m to 2.1m has an average depth of 1.5m. If your pool has a flat bottom with only the ends sloping, use a weighted average: (shallow depth × 0.33 + deep depth × 0.67).

Fill time = Pool volume ÷ fill rate. A standard garden hose delivers about 1,000 litres/hour. A 50,000-litre pool would take about 50 hours with a single hose. Mains supply at higher pressure can reach 2,000–5,000 L/hour. A water tanker can deliver a full pool in a few hours. Check your water meter to estimate your actual flow rate.

Pool volume is essential for: dosing chemicals correctly (chlorine, algaecide, pH adjusters are measured per 1,000 litres); estimating water cost and fill time; sizing your pump and filter (the pump should turn over the full pool volume every 6–8 hours); and calculating heating costs. An incorrectly dosed pool can cause health issues or equipment damage.

How to Measure Your Pool for Volume

Before you can calculate volume, you need accurate measurements. For length and width, measure at the waterline. For depth, measure at both the shallow and deep ends and calculate the average. For pools with irregular shapes, break the pool into simpler geometric sections and add the volumes together.

Pool Shapes and Their Formulas

Rectangular: V = L × W × D
Round/Circular: V = π × r² × D (where r = diameter ÷ 2)
Oval: V = π × (L÷2) × (W÷2) × D
Kidney: V ≈ 0.45 × (A + B) × L × D (A, B = widths at widest points of each lobe)
L-shaped: Split into two rectangles, calculate each, then add

Pump Sizing Rule of Thumb

Your pool pump should be able to circulate the full pool volume once every 6–8 hours. This is called the "turnover rate." Minimum pump flow rate (m³/hr) = Pool volume in m³ ÷ 7. For a 75m³ pool, you need at least a 10.7 m³/hr pump. Oversizing by 10–20% is common to allow for filter resistance.