Measure pool water and dose chlorine
Chemical doses are per gallon — get the pool's volume right first, then the ppm you need to add.
Tools used in this guide
The job
Every pool chemical label starts 'per 10,000 gallons' — so the volume is the number that matters. Once that's right, the chlorine dose to lift from current ppm to target ppm is proportional.
Shape and dimensions
Rectangular uses length × width × average depth (shallow+deep ÷ 2); round uses πr² × depth. Enter meters and read liters and US gallons.
Worked example
An 8×4 m pool averaging 1.5 m deep holds 48,000 L ≈ 12,680 gal. Raising free chlorine 2 ppm with 12 % liquid chlorine takes ≈ 0.8 L — the tool reports both liters and the product amount.
Where it stops
Dose math assumes the product's % available chlorine on the label. Stabilizer (CYA), sunlight, and bather load decide how fast the ppm falls back — that's testing, not arithmetic.