How do you calculate pool volume in gallons?

Multiply length x width x average depth in feet, then multiply by 7.48 gallons per cubic foot. A 32 x 16 ft pool averaging 5 ft deep holds about 19,149 gallons.

Why use 7.48 as the gallon factor?

One cubic foot of water equals 7.48 US gallons. For rectangular pools use 7.48; for oval or curved shapes drop toward 6.7 to account for the volume lost at the rounded edges.

What is average depth and how do I find it?

Average depth is the shallow-end depth plus the deep-end depth divided by two. For a pool that runs 3 ft to 7 ft, average depth is 5 ft.

How accurate is a rectangular pool volume estimate?

For true rectangles it is within a few percent. For kidney or free-form pools it tends to overestimate, so trim the shape factor or measure an honest average width.

Why does pool volume matter for chlorine dosing?

Chemical doses are rated per 10,000 gallons. If your real volume is 19,149 gallons but you dose as if it were 15,000, you will chronically under-chlorinate and risk algae.

Pool volume vs spa volume, what is the difference?

Same formula, but spas are far smaller and often use a lower gallon factor for curved shells, so a spa may hold under 1,000 gallons versus 15,000-plus for a residential pool.

Pool, Spa & Water Treatment Chemistry calculator

Pool Volume Calculator

Pool volume is the total water your pool holds in gallons, and it is the single most important number in pool chemistry because every dose of chlorine, acid, or stabilizer is calculated per 10,000 gallons. Pool service techs, builders, and homeowners use it to size chemicals, pumps, and heaters correctly. Guess the volume high and you waste chemical; guess it low and you never hit your free chlorine target. Getting this number right once saves money and headaches on every treatment for the life of the pool.

What this calculator does

Estimate pool water volume from average length, width, depth, and a shape conversion factor.
Use it before chemical dosing, turnover planning, heat estimates, or refill cost checks.
It multiplies length by width by average depth by a gallon-per-cubic-foot factor to estimate total pool water volume.

Formula used

Pool volume = length x width x average depth x gallon factor

Inputs explained

Pool length: Use the measured swim area length.
Pool width: Use average width for irregular pools.
Average water depth: Average the shallow and deep ends.
Shape gallon factor: Use 7.48 for rectangular estimates or a lower factor for curved shapes.

How to use the result

Use it once when commissioning a pool or when you inherit a pool with no documented volume, then reuse the result for every chemical dose.
For irregular, kidney, or free-form shapes this rectangular estimate can be off by 10-20 percent, so measure average width and average depth carefully or apply a lower shape factor.

Current U.S. benchmarks

Global copper trades at $13,552 per tonne (IMF via FRED, Jun 2026), up 37.8% in a year, and U.S. industrial electricity averages 8.66 cents per kWh. Both feed electrified-hardware unit economics.

Common questions

How do you calculate pool volume in gallons? Multiply length x width x average depth in feet, then multiply by 7.48 gallons per cubic foot. A 32 x 16 ft pool averaging 5 ft deep holds about 19,149 gallons.
Why use 7.48 as the gallon factor? One cubic foot of water equals 7.48 US gallons. For rectangular pools use 7.48; for oval or curved shapes drop toward 6.7 to account for the volume lost at the rounded edges.
What is average depth and how do I find it? Average depth is the shallow-end depth plus the deep-end depth divided by two. For a pool that runs 3 ft to 7 ft, average depth is 5 ft.
How accurate is a rectangular pool volume estimate? For true rectangles it is within a few percent. For kidney or free-form pools it tends to overestimate, so trim the shape factor or measure an honest average width.
Why does pool volume matter for chlorine dosing? Chemical doses are rated per 10,000 gallons. If your real volume is 19,149 gallons but you dose as if it were 15,000, you will chronically under-chlorinate and risk algae.

Last reviewed 2026-05-12.