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Pool Capacity Calculator

Capacity means two things around a pool: how much water fits in it and how many people can swim at the same time. This pool capacity calculator gives you both. Enter the footprint and depth, and you get gallons, liters and a bather load figure based on public pool guidance.

Pool capacity calculator cutaway of a pool with a shallow end and deep end water line

Run the numbers

Formula used

Swimmers = (Shallow Area / 15) + (Deep Area / 20)

Your result

Water capacity
19,150 gallons
In liters
72,491 L
Safe swimmer load
30 people
Surface area
512 sq ft

Results update as you type. Round up when you buy materials.

How the pool capacity calculator works

Water capacity is area times average depth times 7.48. Swimmer capacity uses the shallow and deep split, since the shallow end holds more standing swimmers per square foot than the deep end.

Health codes vary by state, so treat the swimmer number as a planning figure for a backyard party rather than a legal limit for a commercial site.

The formula, step by step

Swimmers = (Shallow Area / 15) + (Deep Area / 20)

  • Work out the total surface area of the pool.
  • Split it between shallow water and deep water using your own estimate.
  • Allow 15 square feet per swimmer in shallow water.
  • Allow 20 square feet per swimmer in water over 5 feet deep.
  • Add both figures for the total safe load.

Worked example

A 16 by 32 foot pool has 512 square feet of surface, split 60 percent shallow and 40 percent deep.

Shallow: 307 / 15 = 20 swimmers. Deep: 205 / 20 = 10 swimmers.

Total safe load is about 30 people, and the pool holds roughly 19,400 gallons at a 5 foot average depth.

Watch it done

This short video walks through the same job in real life, so you can match what you see on screen to what you do at the pool.

Video guide: How to Work Out Pool Water Capacity by Leslie's. Video hosted on YouTube.

Tips before you start

Skimmer performance drops when a pool is crowded, because bodies push debris under the surface. Run the pump through the whole party and for two hours after it ends.

Every swimmer brings sweat, sunscreen and body oils into the water. A busy weekend can burn through chlorine three times faster than a quiet one, so test the next morning.

Pool Capacity Calculator FAQs

How many people can safely swim in my pool?

Allow 15 square feet of shallow water and 20 square feet of deep water per person. A 16 by 32 pool handles about 30 swimmers at once.

Is pool capacity the same as pool volume?

Water capacity is the same as volume. Swimmer capacity is a separate number based on surface area, not gallons.

Do kids count as full swimmers?

For planning, yes. Small children move unpredictably and need more room to supervise, not less.

How does a crowd affect water balance?

Heavy use drops free chlorine fast and raises the load on your filter. Shock the pool after a large gathering and check pH the next day.