Pool Calculator

Pool Volume Calculator

Calculate total gallons for rectangular, round, oval, and freeform pools. Get gallons, liters, cubic feet, water weight, and estimated fill time.

The Short Answer: A standard 12 × 24-foot rectangular pool with an average depth of 5 feet holds about 10,800 gallons. A 15-foot round pool at 4 feet deep holds about 5,300 gallons. Multiply length × width × average depth × 7.48 for rectangular pools.

Pool Volume Calculator

Select your pool shape and enter dimensions in feet.

Gallons
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Liters
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Cubic feet
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Water weight
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Fill time (garden hose)
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Fill time assumes a standard garden hose at ~10 gallons per minute. Actual flow rates vary by water pressure and hose diameter.

4 pool shapes
Gallons, liters, and fill time

How to Calculate Pool Volume

Pool volume determines chemical dosage, heater sizing, pump flow rates, and fill time. Every pool chemical — chlorine, pH balancer, algaecide — is dosed per gallon. An incorrect volume estimate means incorrect chemistry, which means green water or damaged equipment. Getting this number right matters.

For pools with a gradual slope from shallow to deep end, the average depth formula works well. For pools with a hopper bottom (flat shallow, sudden drop to deep), the calculation is more complex — the freeform option with a measured or estimated surface area and average depth gives a reasonable approximation.

Why Pool Volume Matters

Chemical dosing is the primary reason you need to know your pool's volume. Chlorine, for example, is typically dosed at 1–3 ppm (parts per million). For a 15,000-gallon pool, 1 ppm of free chlorine requires about 2 ounces of liquid chlorine or 0.5 ounces of granular dichlor. Double the pool volume, double the chemical dose. The CDC's Model Aquatic Health Code sets standards for public pools, but even residential pools should maintain 1–3 ppm chlorine and a pH between 7.2 and 7.6.

Pump and filter sizing also depends on volume. A pool pump should turn over the entire volume at least once per 8 hours — a 20,000-gallon pool needs a pump that moves at least 42 gallons per minute.

Frequently Asked Questions

Select your pool shape above, enter the dimensions in feet, and the calculator returns gallons instantly. As a quick reference: a 12 × 24-foot pool at 5 feet average depth holds about 10,800 gallons. A 16 × 32-foot pool at 5.5 feet holds roughly 21,000 gallons. Round above-ground pools: a 15-foot pool at 4 feet deep holds about 5,300 gallons; an 18-foot pool at 4 feet holds about 7,600 gallons.

A standard garden hose delivers about 10 gallons per minute (depending on water pressure). At that rate, a 10,000-gallon pool takes roughly 17 hours to fill. A 20,000-gallon pool takes about 33 hours. The calculator above shows fill time for your specific volume. Some homeowners use a water delivery service for large pools — a tanker truck can deliver 6,000–8,000 gallons in one load.

Water weighs 8.34 pounds per gallon. A 15,000-gallon pool holds about 125,000 pounds — over 62 tons — of water. This weight is a structural consideration for above-ground pools and decks built adjacent to in-ground pools. The calculator above shows water weight for your pool.

For pools with a gradual slope, measure the shallow end and deep end depths, then average them: (shallow + deep) ÷ 2. For pools with a flat shallow area that drops suddenly to a deep section (hopper bottom), measure the shallow depth, the deep depth, and estimate what percentage of the pool floor is shallow vs. deep. A weighted average gives a more accurate result than a simple average.

The Bottom Line

Your pool's volume in gallons is the foundation for every maintenance decision — chemical dosing, pump sizing, heater capacity, and water cost. Measure the dimensions, run the calculation, and write the number down somewhere permanent. You'll reference it every time you add chemicals, troubleshoot water clarity, or size replacement equipment. This calculator gives you gallons, liters, cubic feet, water weight, and fill time all at once.

Cubic Feet Calculator

Volume conversions between cubic feet, gallons, liters, and more.

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Pool deck and coping — concrete for the area around the pool.

Deck Calculator

Poolside deck materials — boards, framing, and stairs.