Pool Volume & Chlorine Calculator
Calculate pool volume for rectangular, round, oval and kidney shapes with sloping floors, then work out the chlorine, shock, acid or alkalinity dose to reach your target reading.
Last reviewed by the Radiatus Cloud team
Pool volume
Chemical dose
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Every dose depends on the volume
Pool chemistry instructions are given per unit of water, so a wrong volume makes every subsequent calculation wrong in the same direction. Guessing high wastes chemicals and pushes readings past target; guessing low leaves the pool under treated while the label appears to have been followed. The volume only has to be worked out once, but it has to be right, and the common error is treating a pool with a sloping floor as if it were uniform depth.
Average depth is not the deep end
For a pool that slopes from a shallow to a deep end, the average depth is the mean of the two, weighted by how much of the floor area each occupies. A pool three feet at one end and eight at the other has an average depth well below five and a half feet if the deep end is a small hopper rather than half the pool. Getting this wrong is the single largest source of volume error in a residential pool.
Dosing to a target rather than a label
Once the volume is known, the dose to move a reading from where it is to where it should be is arithmetic. Liquid chlorine at twelve and a half percent, granular calcium hypochlorite, dichlor and trichlor all carry different available chlorine, and the stabilised forms add cyanuric acid that accumulates permanently until water is replaced. The calculator reports the dose for each product and, where relevant, the side effect it also introduces, which is the part that shortens a pool season when ignored.
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Frequently Asked Questions
How do I work out average depth on a sloping pool?
Measure the shallow and deep depths and estimate what fraction of the floor is each. A common residential shape is roughly two thirds shallow to one third deep, which puts the average nearer the shallow figure than a simple mean would suggest.
Why does the same dose of different chlorine products differ?
Because available chlorine varies: liquid chlorine is typically 10 to 12.5 percent, calcium hypochlorite around 65 to 73 percent, dichlor about 56 percent and trichlor about 90 percent. The tool converts the target increase into the right quantity for each.
What is cyanuric acid lock and why does it matter?
Stabilised chlorine products such as dichlor and trichlor add cyanuric acid with every dose. It protects chlorine from sunlight, but it accumulates and never leaves except by draining and refilling. Above roughly 100 parts per million the chlorine becomes progressively less effective at the same reading.
Should I shock at night?
Yes, or at dusk. Ultraviolet light destroys unstabilised chlorine quickly, so a daytime shock loses a large fraction of the dose before it does any work. Dosing after sunset gives the chlorine the whole night to act.
Is this a substitute for testing?
No. Dose calculations start from a measured current reading, so a reliable test kit is the prerequisite. Test strips drift; a drop based kit or a photometer is worth having if you are dosing rather than guessing.
Privacy & Security
Everything runs in your browser; nothing is uploaded.
How to Use
Enter the pool shape and dimensions, then use the chemistry section to calculate a dose.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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