About Pool Calculus

Pool Calculus is an independent site of free calculators for people who look after their own pool or hot tub.

Why this site exists

Most pool calculators online give you a number and nothing else. You can’t see the formula, you don’t know what product strength it assumed, and two calculators often disagree. We built Pool Calculus so that every answer comes with its working, its assumptions and the sources behind them. If you want to check a dose by hand, everything you need is on the page.

How the calculators are made

• Formulas come from published sources: the CDC and its Model Aquatic Health Code, the U.S. Department of Energy, ENERGY STAR, the EPA, peer-reviewed chemistry and manufacturer specifications. We list them on each page.
• Each calculator is tested against a separate implementation of the same maths before every release. The how we calculate page explains the methods in full.
• Each page shows the date it was last reviewed. We update pages when a source changes or a reader spots a problem.

Who runs it

Pool Calculus is run by a small independent team. We are not pool contractors and we don’t sell chemicals or equipment. We don’t accept payment to recommend products.

How the site is paid for

The site is free to use and is supported by advertising. Ads never change a calculation or a recommendation.

Corrections

If you think a result is wrong, please get in touch with the inputs you used and what you expected. We read every message and fix confirmed errors quickly.