Rectangular pool
Length × Width × Avg depth × 7.48A 32 × 16 ft pool that averages 5 ft deep holds 32 × 16 × 5 × 7.48 = about 19,150 gallons.
Gallons, litres, fill time, cost and salt
Pool Volume Calculator
This pool volume calculator tells you how many gallons or litres your pool holds, for rectangular, round, oval and kidney pools with a sloped or flat bottom. It also works out fill time, water cost, pump size and the salt you need.
Pool gallons calculator
Formulas
Pool Volume Formulas by Shape
Every formula multiplies the surface area of the pool by its average water depth. Multiply cubic feet by 7.48 to get US gallons, or cubic metres by 1,000 to get litres.
Round pool
Diameter × Diameter × Avg depth × 5.875A 24 ft above-ground pool with 4 ft of water holds 24 × 24 × 4 × 5.875 = about 13,540 gallons.
Oval pool
Length × Width × Avg depth × 5.875An 18 × 33 ft oval with 4 ft of water holds 18 × 33 × 4 × 5.875 = about 13,960 gallons.
Kidney pool
(A + B) × Length × Avg depth × 3.37A and B are the widths of the two ends. With A = 10, B = 15, length 30 and 5 ft average depth, the pool holds about 12,620 gallons.
Average depth = (shallow end + deep end) ÷ 2. Measure water depth, not wall height. Above-ground pools are usually filled about 6 inches below the top of the wall. For tanks and other containers, try the water tank capacity calculator.
Reference
Pool Gallons Chart for Common Sizes
Quick answers for the most popular above-ground and inground pool sizes. Fill times assume a garden hose running at 8 gallons per minute.
| Diameter | 42 in water | 46 in water | 48 in water | Fill time (48 in) |
|---|---|---|---|---|
| 12 ft | 2,960 | 3,240 | 3,380 | 7 h 3 min |
| 15 ft | 4,630 | 5,070 | 5,290 | 11 h 1 min |
| 18 ft | 6,660 | 7,300 | 7,610 | 15 h 52 min |
| 21 ft | 9,070 | 9,930 | 10,360 | 21 h 35 min |
| 24 ft | 11,840 | 12,970 | 13,540 | 28 h 12 min |
| 27 ft | 14,990 | 16,420 | 17,130 | 35 h 42 min |
| 30 ft | 18,510 | 20,270 | 21,150 | 44 h 4 min |
| 33 ft | 22,390 | 24,530 | 25,590 | 53 h 19 min |
| Size | 4 ft average | 5 ft average | 6 ft average | Fill time (5 ft) |
|---|---|---|---|---|
| 10 × 20 ft | 5,980 | 7,480 | 8,980 | 15 h 35 min |
| 12 × 24 ft | 8,620 | 10,770 | 12,930 | 22 h 26 min |
| 14 × 28 ft | 11,730 | 14,660 | 17,590 | 30 h 33 min |
| 15 × 30 ft | 13,460 | 16,830 | 20,200 | 35 h 4 min |
| 16 × 32 ft | 15,320 | 19,150 | 22,980 | 39 h 54 min |
| 18 × 36 ft | 19,390 | 24,240 | 29,080 | 50 h 30 min |
| 20 × 40 ft | 23,940 | 29,920 | 35,910 | 62 h 20 min |
Why ours
Why This Pool Volume Calculator Is Better
Most pool calculators give you one number. This one answers the next questions every pool owner has.
Four shapes, live preview
Rectangle, round, oval and kidney pools, with a top view and side profile that redraw as you type.
Sloped or flat bottom
Enter shallow and deep ends for inground pools, or a single depth for above-ground pools. The average is handled for you.
Feet or metres
Switch units and your measurements convert automatically. Results show US gallons, litres, imperial gallons and cubic volume.
Fill time and cost
Know how many hours your hose will run and roughly what the water will cost before you start filling.
Pump sizing
See the flow rate needed to turn over all the water in 8 hours, the usual target for a clean, clear pool.
Saltwater ready
Get the exact amount of pool salt to reach your chlorinator target, in pounds or kilograms and in whole bags.
Guide
How to Use the Pool Volume Calculator
Grab a tape measure. You will have your pool gallons in under a minute.
- Choose units and shape
Pick feet or metres, then the shape closest to your pool. For L-shaped pools, measure each rectangle separately and add the results.
- Measure the surface
Measure the inside length and width at the water line, or the diameter for a round pool.
- Measure water depth
Turn on Sloped bottom and enter the shallow and deep end depths, or turn it off and enter one depth.
- Add filling and salt details
Optionally enter your hose flow rate, water price and salt levels for time, cost and salt results.
- Use your results
Write down your gallons for chemical dosing, then copy or share the result for your pool service.
Benefits
Why Knowing Your Pool Volume Matters
Almost every pool care decision starts with how many gallons you have.
Accurate chemical doses
Chlorine, shock, pH and alkalinity products are all dosed per gallon. Guessing leads to wasted chemicals or cloudy, unsafe water.
Right-sized equipment
Pumps, filters and heaters are matched to pool volume. Size them correctly and you save on running costs, which you can estimate with the electricity cost calculator.
Budget for filling
Know the water bill and how long the hose will run before you start, so you can plan around delivery or utility schedules.
Plan a new pool
Compare sizes and depths before you build, then estimate the hardscape with the concrete calculator.
FAQ
Pool Volume FAQ
How do I calculate pool volume in gallons?
Find the surface area, multiply by the average water depth, then convert. For a rectangular pool, gallons = length × width × average depth × 7.48. For a round pool, gallons = diameter × diameter × average depth × 5.875, with all measurements in feet.
How many gallons are in a 24 ft round pool?
A 24 ft round above-ground pool filled to 4 feet (48 inches) of water holds about 13,540 gallons. At 46 inches it holds about 12,970 gallons, and at 42 inches about 11,840 gallons.
How many gallons are in a 16 x 32 pool?
A 16 × 32 ft inground pool with an average depth of 5 feet holds about 19,150 gallons. If it runs from 3.5 ft to 8 ft deep, the average depth is 5.75 ft and it holds about 22,020 gallons.
How do I find the average depth of my pool?
Add the shallow end depth and the deep end depth, then divide by 2. Measure the water depth, not the wall height. If most of the pool is shallow, the true average will be a little lower than this simple figure.
How long does it take to fill a pool with a garden hose?
A typical garden hose delivers 5 to 10 gallons per minute. At 8 gallons per minute, a 20,000 gallon pool takes about 2,500 minutes, or roughly 42 hours. A water delivery truck can fill the same pool in a few hours.
How much salt does a saltwater pool need?
Pounds of salt = gallons × ppm increase × 8.34 ÷ 1,000,000. A 15,000 gallon pool going from 0 to 3,200 ppm needs about 400 pounds, or ten 40 lb bags. Check your chlorinator manual for its ideal salt level.
How many litres does my pool hold?
In metric units, multiply length × width × average depth in metres to get cubic metres, then multiply by 1,000 for litres. A 10 × 5 m pool that averages 1.5 m deep holds 75 cubic metres, or 75,000 litres.
What size pump does my pool need?
Most pools should turn over all their water in about 8 hours. Divide your pool gallons by 480 to get the flow rate needed in gallons per minute. A 20,000 gallon pool needs about 42 gallons per minute.
Why is it important to know my pool volume?
Chlorine, shock, pH and alkalinity chemicals are all dosed by gallons. Knowing your exact volume prevents under-treating, which leads to algae, and over-treating, which wastes money and can irritate skin and eyes.
Know Your Gallons, Treat Your Pool Right
Use the pool volume calculator before you fill, treat or open your pool for the season, then explore our other measurement tools.
Calculate my pool volumeResults are estimates based on standard shapes. Always follow the product label and your equipment manual when dosing chemicals.