About Pool Calc Lab

Pool Calc Lab is a set of free calculators for pool and hot tub owners: water volume, salt and chlorine dosing, pH and alkalinity adjustment, evaporation loss, and heating cost by state.

The site exists because most pool calculators online fall into one of two buckets: sales tools built by equipment manufacturers that steer every answer toward their product, or bare input boxes that give you a number with no way to check it. We take the opposite approach. Every calculator on this site shows the formula it uses, walks through a worked example by hand, and tells you honestly where the estimate is exact (salt math) and where it is an approximation (pH dosing, which depends on your alkalinity).

Where the numbers come from

• Chemical dosing factors are the standard industry values used across pool-care references, stated per 10,000 gallons and scaled to your volume.
• Energy prices in the heating cost calculator are state-level residential averages from the U.S. Energy Information Administration (EIA), refreshed periodically and labeled with their vintage in the results.
• The evaporation calculator uses the Carrier equation, the standard engineering relationship for evaporation from water surfaces.

What we are not

We do not sell pool equipment or chemicals, and no manufacturer pays for placement in any calculator result. The site is supported by display advertising. Calculator results are estimates for planning purposes, not professional advice, product label directions always take precedence for chemical handling and dosing (see our disclaimer).

Questions, corrections, or a calculator you wish existed? Reach out via the contact page, corrections are especially welcome and get fixed fast.