Pool Volume Calculator
Enter your pool shape, dimensions, and depths to calculate total water volume in gallons or litres, surface area, water weight, and hose fill time.
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About Pool Volume Calculator
The Pool Volume Calculator tells you how many gallons or liters of water your swimming pool holds. Choose from rectangular, round, oval, and kidney shapes, enter your dimensions with separate shallow-end and deep-end depths, and get the volume in US gallons, imperial gallons, liters, cubic meters, and cubic feet — plus surface area, water weight, and an estimated fill time. Knowing your pool volume is the essential first step for dosing chlorine and other chemicals, sizing a heater or pump, and budgeting your water bill.
How to Calculate Pool Volume
Every pool volume calculation follows the same two-part logic: find the surface area of the water, then multiply by the average depth. The only thing that changes between shapes is the area formula.
Then convert the raw volume into the unit you want. If you measured in feet, the volume comes out in cubic feet, so:
- US gallons = cubic feet × 7.48
- Liters = cubic feet × 28.32
If you measured in meters, the volume is in cubic meters, so liters = cubic meters × 1000 and US gallons = cubic meters × 264.17.
Volume Formula for Each Pool Shape
For the kidney shape, A and B are the widths of the two rounded lobes, and Length is the longest straight-line distance across the pool. The 0.45 constant is the widely used pool-industry approximation for the curved kidney outline.
Common Pool Sizes and Volumes
These reference figures assume an average depth (shallow + deep divided by two). Your exact volume depends on your real dimensions.
| Pool | Dimensions | Avg Depth | Approx. US Gallons |
|---|---|---|---|
| Small rectangular | 24 × 12 ft | 4.5 ft | ≈ 9,700 |
| Medium rectangular | 32 × 16 ft | 4.5 ft | ≈ 17,200 |
| Large rectangular | 40 × 20 ft | 5.5 ft | ≈ 32,900 |
| Round above-ground | 24 ft diameter | 4 ft | ≈ 13,500 |
| Round above-ground | 18 ft diameter | 4 ft | ≈ 7,600 |
| Oval above-ground | 15 × 30 ft | 4 ft | ≈ 10,600 |
Why Pool Volume Matters
Chlorine, pH adjusters, algaecide, and shock are all dosed per volume of water. Guessing wastes product or leaves the water unsafe.
The heater and its run time are chosen from the number of gallons you need to warm to your target temperature.
A pool pump should turn over the entire volume roughly once every 8 hours, so flow rate is set from total gallons.
Knowing the volume lets you estimate the cost to fill or top up the pool from your local water rate.
How to Use This Calculator
- Choose your pool shape: Select rectangular, round, oval, or kidney. The diagram and required fields update automatically.
- Pick your units: Choose imperial (feet) or metric (meters).
- Enter the dimensions: Fill in the length, width, or diameter the shape needs.
- Enter shallow and deep depths: Use the depth at each end. For a flat-floored pool, enter the same value for both.
- Click Calculate: See your volume in gallons and liters, surface area, water weight, fill time, and a step-by-step breakdown.
Frequently Asked Questions
How do I calculate the volume of my pool?
Multiply the pool's surface area by its average depth to get the volume, then convert to gallons or liters. For a rectangular pool the area is length times width; for a round pool it is pi times the radius squared. Average depth is the shallow-end depth plus the deep-end depth divided by two. In imperial units, multiply cubic feet by 7.48 to get US gallons.
How many gallons is my pool?
It depends on the size. A typical 32 by 16 foot rectangular inground pool with a floor sloping from 3 to 6 feet (4.5 foot average depth) holds about 17,200 US gallons. A 24 foot round above-ground pool with a 4 foot depth holds about 13,500 US gallons. Enter your own dimensions to get an exact figure.
How do I find the average depth of a pool?
Add the depth at the shallow end to the depth at the deep end and divide by two. For example, a pool that is 3 feet at the shallow end and 8 feet at the deep end has an average depth of 5.5 feet. If your pool has a flat floor, the average depth simply equals that single depth.
How do I calculate the volume of a kidney-shaped pool?
A common approximation multiplies 0.45 by the sum of the two widths (A plus B), then by the length, then by the average depth. Multiply the result by 7.48 for US gallons if you measured in feet. This estimate is accurate enough for chemical dosing and heating calculations.
How much does the water in a pool weigh?
Water weighs about 8.34 pounds per US gallon, or 1 kilogram per liter. A 20,000 gallon pool therefore holds roughly 167,000 pounds of water, about 83 US tons. This is why the ground and structure under a pool must be well supported.
How long does it take to fill a pool with a garden hose?
A typical garden hose delivers about 9 gallons per minute, or roughly 540 gallons per hour. A 20,000 gallon pool would take about 37 hours to fill. Using multiple hoses or a larger supply line shortens the time proportionally.
Additional Resources
Reference this content, page, or tool as:
"Pool Volume Calculator" at https://MiniWebtool.com/pool-volume-calculator/ from MiniWebtool, https://MiniWebtool.com/
by miniwebtool team. Updated: July 6, 2026