How many gallons is a typical pool?

Small above-ground pools hold 3,000–7,000 gallons. Standard inground pools hold 15,000–30,000 gallons. Large residential pools can hold 30,000–50,000 gallons. Commercial pools hold 100,000+ gallons.

How do I measure average pool depth?

Measure the depth at the shallow end and the deep end. Average depth = (shallow + deep) ÷ 2. For pools with a gradual slope this is accurate. For pools with a hopper bottom, measure at 3–4 points and average.

How long does it take to fill a pool?

A standard garden hose delivers about 500 gallons per hour. A 20,000-gallon pool takes about 40 hours to fill. Using two hoses cuts the time in half. Some areas require a permit for large water draws.

How much chlorine do I need?

Chlorine dosing depends on pool volume and current levels. Typically, 1 lb of granular chlorine raises 10,000 gallons by 5–10 ppm. For maintenance, you need 1–3 ppm free chlorine, tested 2–3 times per week.

How much does it cost to fill a pool with water?

Municipal water costs $5–$15 per 1,000 gallons. A 20,000-gallon pool costs $100–$300 to fill. Water delivery by tanker truck costs $200–$600 for 6,000 gallons. Check local rates before filling.

What size pump do I need?

The pump should turn over your entire pool volume in 6–8 hours. For a 20,000-gallon pool: 20,000 ÷ 8 = 2,500 gallons per hour (42 GPM). Choose a pump rated for this flow at your total dynamic head.

Pool Volume Calculator

Calculate swimming pool water volume in gallons. Enter pool dimensions and shape for accurate volume and chemical dosing estimates.

Pool Shape

Length

Width

Shallow End Depth

Deep End Depth

Average Depth

5.8 ft

Pool Volume

22,021 gal

2,944 ft³

Fill Time (hose)

44 hrs

~500 gal/hr

Pump Size (8-hr turnover)

46 GPM

Planning notes, formulas, and examples

About the Pool Volume Calculator

Knowing your swimming pool's exact volume in gallons is essential for proper chemical dosing, heater sizing, pump selection, and water fill time estimates. Under-dosing chemicals leaves water unsafe; over-dosing wastes money and can irritate skin and eyes.

This calculator determines pool volume for rectangular, circular, and oval pools. For pools with varying depth (shallow end to deep end), it uses the average depth for an accurate calculation. Standard conversion is 7.48 gallons per cubic foot.

Whether you're filling a new pool, balancing water chemistry, or sizing a pool heater, This calculator gives you the precise gallon count you need.

When This Page Helps

Pool chemicals, heaters, and filters are all sized based on water volume. An inaccurate estimate means improper chemical balance, undersized equipment, or wasted money. This calculator handles common pool shapes and variable depths.

How to Use the Inputs

Measure your pool's length and width in feet.
Measure the shallow end and deep end depths.
Select the pool shape.
Review the average depth and total gallons.
Use the gallon count for chemical and equipment sizing.
Record your pool volume for future reference.

Formula used

Average Depth = (Shallow + Deep) ÷ 2
Rectangular: Gallons = L × W × Avg Depth × 7.48
Circular: Gallons = π × r² × Avg Depth × 7.48
Oval: Gallons = π × (L/2) × (W/2) × Avg Depth × 7.48

Example Calculation

Result: 22,052 gallons

A 32×16 ft pool with 3.5 ft shallow and 8 ft deep end: average depth = 5.75 ft. Volume = 32 × 16 × 5.75 = 2,944 ft³ × 7.48 = 22,021 gallons.

Tips & Best Practices

Measure depth from the water line, not the pool rim.
For L-shaped pools, calculate each section separately and add.
Pool heaters need 1 BTU per gallon per degree F of temperature rise per hour.
Chemical calculators require your pool volume — keep this number handy.
A garden hose fills at about 500 GPH; a 20,000-gallon pool takes ~40 hours.
Most residential pool pumps turn over the entire volume in 6–8 hours.

Pool Volume by Shape

Rectangular pools are most common: L × W × Avg Depth × 7.48. Circular above-ground pools use πr² × depth × 7.48. Kidney-shaped pools are best split into a circle and rectangle, calculated separately.

Why Pool Volume Accuracy Matters

Every pool chemical is dosed per gallon: chlorine, pH adjusters, algaecides, and stabilizers. A 20% volume error means 20% chemical error — enough to cause cloudy water, algae blooms, or swimmer discomfort.

Equipment Sizing Based on Volume

Pool pumps should circulate the entire volume 1–2 times per day. Filters are sized at 1–2 GPM per square foot of filter area. Heaters are rated in BTU — larger volumes need more BTUs for the same temperature rise.

Above-Ground Pool Volumes

Common sizes: 12 ft round = 3,398 gal (4 ft deep). 15 ft round = 5,310 gal. 18 ft round = 7,646 gal. 24 ft round = 13,594 gal. 12×24 ft oval = 6,797 gal. Always verify with the manufacturer.

Sources & Methodology

Last updated: February 8, 2026

Frequently Asked Questions

Small above-ground pools hold 3,000–7,000 gallons. Standard inground pools hold 15,000–30,000 gallons. Large residential pools can hold 30,000–50,000 gallons. Commercial pools hold 100,000+ gallons.