Pool Volume Calculator

Work out how many gallons and litres your pool holds — rectangular or round, using the average of the shallow and deep ends.

What this calculator does

Pool volume drives every maintenance number you’ll ever use: chlorine and shock dosing, pump and filter sizing, heater run-times, even the water bill for a refill. Enter the pool’s shape and dimensions with the shallow- and deep-end depths, and this calculator averages the depth and returns gallons, litres, and the weight of the water — a figure that surprises most people.

How to use it

  1. Pick the shape: rectangular or round.
  2. Enter the dimensions in feet.
  3. Enter the shallow and deep end depths — the calculator averages them.

The formula

rectangular: gallons = L × W × avg depth × 7.48 round: gallons = π × (D/2)² × avg depth × 7.48

A worked example

A 30 × 15 ft pool sloping from 3 ft to 6 ft has an average depth of 4.5 ft: 30 × 15 × 4.5 × 7.48 ≈ 15,148 gallons — about 57,300 litres, weighing over 126,000 lb. That volume is the number every dosing chart on a chemical bottle asks for, which is why it’s worth calculating once and writing down.

Common questions

Is averaging the two depths accurate?
For a straight, constant slope, yes — exactly. Pools with a sudden drop-off or a diving well need splitting into sections, each calculated separately and summed.
How do I handle an oval pool?
A good estimate: length × width × avg depth × 7.48 × 0.89 — the 0.89 corrects the corners an oval doesn’t have.
Why does volume matter for chemicals?
Every dose on a chlorine or shock label is “per 10,000 gallons”. Guessing the volume wrong doses the pool wrong in exact proportion.