PoolCalc is a set of free tools for working out what a swimming pool actually needs — how much water it holds, how much of a chemical to add, what size pump will turn it over, and what all of that costs to run.
Why this site exists
Most pool advice arrives as a rule of thumb. Add a cup of this. Run the pump eight hours. Shock it weekly. Rules of thumb are fine until your pool is not the pool the rule was written for — and then they quietly waste money, or worse, leave water that is not properly sanitised.
Every number on this site is worked out from your pool: your volume, your readings, your product strength, your electricity rate. Where a figure rests on an assumption, that assumption is written next to the answer rather than buried.
How the calculators are built
Each calculator states the formula it uses, shows a worked example, and lists both what it assumes and where it falls down. If a calculation cannot be trusted in a particular situation, the page says so instead of returning a confident number.
The arithmetic runs entirely in your browser. Nothing you type is sent to a server, stored, or logged — the calculators work the same way whether you are signed in to anything or not, because there is nothing to sign in to.
The chemistry figures are derived from the active ingredient in the product you select, not copied from a generic dosing chart. That is why choosing 6% household bleach gives a different answer from 12.5% liquid chlorine: it should.
You can read the full method on the How We Calculate page.
What this site is not
- It is not a substitute for testing your water. A calculator can only work with the readings you give it.
- It is not professional advice. For a pool that will not come right, or any situation involving illness, take a sample to a pool professional.
- It does not sell chemicals or equipment, and it does not recommend brands.
Corrections
If you find a figure that looks wrong, please say so. Getting a dose wrong on a page like this has real consequences for real pools, so corrections are taken seriously and acted on quickly. Write to hello@swimmingpoolcalculator.online.
Contact
Questions, corrections and suggestions are all welcome through the contact page.