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CalcBelt

Pool volume calculator

Enter your pool's shape, size and depths to get how many gallons of water it holds, with liters, cubic feet and the time to fill it with a hose.

Units
Pool shape

Inside the walls, at the waterline. Where to measure

Depth

Water depth, not wall height.

Filling (optional)
gallons a minute

Time how long your hose takes to fill a 5-gallon bucket: 60 seconds is 5 gallons a minute.

Not covered: chlorine, salt and shock doses. Follow the product label or ask a pool professional; they'll want the volume above.

Pool volume

22,023 gallons

83,365 liters · 83.4 m³

Surface area
512 sq ft
Average depth
5 ft 9 inHalfway between the shallow and deep ends
Cubic feet
2,944

Water to fill it

per 1,000 gallons

From your water bill. Rates vary a lot by town.

How it's calculated
  1. Surface: length × width = 512 sq ft
  2. Average depth: (3.5 ft + 8 ft) ÷ 2 = 5.75 ft
  3. Volume: 512 sq ft × 5.75 ft = 2,944 cu ft
  4. 2,944 cu ft × 7.4805 gallons per cu ft = 22,023 gallons

Estimates use manufacturer data sheets and industry guides (sources). Check local codes and your supplier's figures before you order.

How to use the pool volume calculator

  1. Pick the shape: rectangle, round, oval with round ends, or a known surface area for a free-form pool.
  2. Measure the length and width, or the diameter, inside the walls at the waterline.
  3. Enter the water depth at the shallow and deep ends, or one depth for a flat-bottom or above-ground pool.
  4. Read the gallons. Add your hose's flow if you want the time to fill it.

How to calculate pool volume

Average depth = (shallow end + deep end) ÷ 2
Rectangle: length × width × average depth × 7.48
Round: π × (diameter ÷ 2)² × depth × 7.48
Oval: [(length − width) × width + π × (width ÷ 2)²] × average depth × 7.48

Example: a 16 × 32 ft pool, 3.5 ft deep at the shallow end and 8 ft at the deep end.

  • Average depth: (3.5 + 8) ÷ 2 = 5.75 ft
  • Volume: 16 × 32 × 5.75 = 2,944 cubic feet
  • Gallons: 2,944 × 7.4805 = 22,023 gallons, or 83,365 liters
Pool volume calculator diagram: a rectangular pool seen from above with its length and width measured inside the walls, a side view showing the water depth at the shallow and deep ends with the average depth halfway between, and a round pool measured across its diameter.
Where to measure: length and width inside the walls at the waterline, and the water depth at each end. For a round pool, the diameter.

Where 7.48 comes from

A US gallon is exactly 231 cubic inches (NIST), and a cubic foot is 1,728 cubic inches, so a cubic foot holds 1,728 ÷ 231 = 7.4805 gallons. In metric it’s simpler: a cubic meter is 1,000 liters, and a US gallon is 3.785 liters.

Round and oval pools

A round pool’s surface is π times the radius squared. Pool guides often use a shortcut of 5.9 for round pools, which is the same math rounded: π ÷ 4 × 7.48 = 5.875. The calculator uses the exact shape.

The oval here is the common pool shape with two straight sides and half-circle ends: a rectangle as long as the straight part plus a circle as wide as the pool. A 15 × 30 ft oval is (30 − 15) × 15 + π × 7.5² = 401.7 sq ft, so at 4 ft deep it holds about 12,020 gallons. For a kidney or free-form pool, use the surface area from the plans and pick “Known area”.

What’s not covered

Chlorine, salt and shock doses are left out on purpose: they depend on the product and your water test. Follow the label or ask a pool professional, who will want the gallons from this page. To check the area around the pool for pavers or a slab, the paver calculator and concrete calculator work from the same measurements.

Questions and answers

How many gallons is my pool?

Length × width × average depth in feet, times 7.48 gallons per cubic foot, for a rectangular pool. A 16 × 32 ft pool that's 3.5 ft deep at the shallow end and 8 ft at the deep end averages 5.75 ft and holds about 22,000 gallons. Round and oval pools use their own area, which the calculator works out.

How do you calculate the volume of a pool?

Find the surface area, multiply by the average depth to get cubic feet, then multiply by 7.48 for US gallons. The average depth is the shallow end plus the deep end, divided by two, the way Salt Lake County's pool inspectors work it out. In metric, cubic meters × 1,000 gives liters.

How many gallons are in an Olympic swimming pool?

At least 660,000 gallons. World Aquatics requires Olympic pools to be 50 m long, 25 m wide and at least 2 m deep, which is 2,500 m³, or about 660,430 US gallons. At the 3 m depth it recommends for pools used for several sports, it's 3,750 m³, about 990,645 gallons.

How many gallons are in a round pool?

π × (diameter ÷ 2)² × depth × 7.48. A 24 ft round pool with 4 ft of water holds about 13,536 gallons; an 18 ft one at 4 ft holds about 7,614. Measure the diameter inside the wall and the depth of the water, not the wall.

How do I find the average depth of a pool?

Add the depth at the shallow end and at the deep end, and divide by two. A pool 3.5 ft at one end and 8 ft at the other averages 5.75 ft. If the floor slopes unevenly, with a long flat shallow area and a steep hopper, measure it as two sections and add them for a closer figure.

How long does it take to fill a pool with a hose?

Gallons ÷ gallons per minute ÷ 60 gives the hours. Time how long your hose takes to fill a 5-gallon bucket: 30 seconds means 10 gallons a minute, so a 22,000-gallon pool takes about 37 hours.

How much does the water in a pool weigh?

About 8.33 lb per gallon, the figure on Salt Lake County's pool calculation sheet, or 62.4 lb per cubic foot. A 22,000-gallon pool holds about 183,000 lb of water.

How much chlorine or salt does my pool need?

That isn't covered here. Doses depend on the product and your water test, so follow the label or ask a pool professional. They'll ask for the volume, which is what this calculator gives you.

Sources

Figures checked October 2026.