Pool Chemical Calculator
Dosing a pool correctly is simple arithmetic once you have the right numbers: the amount of product to add equals your pool volume times the ppm change you want times the dose rate on the product label. Because chemical strengths vary so much, this calculator asks you to read the dose rate (the product needed to raise 10,000 gallons by 1 ppm) from your own label, then computes the total dose, the dose per 10,000 gallons, and the final target. Always follow the label and add chemicals gradually, retesting as you go.
Pool dosing formula
Total dose (oz) = (volume / 10,000) * ppm change * dose rate
Total dose (lb) = total dose oz / 16
Dose per 10,000 gal = ppm change * dose rate
Resulting level = current reading + ppm change
The dose rate from your label is the ounces needed to raise 10,000 gallons by 1 ppm. Scaling by your volume and the ppm change gives the total amount to add. One pound equals 16 ounces.
Pool chemistry context
- One US gallon equals 3.785 liters; one pound equals 16 ounces.
- Test water first, then dose only the difference to your target.
- Granular and liquid chemicals have very different dose rates.
- The CDC publishes healthy swimming and disinfection guidance.
- Add chemicals gradually and retest; never mix products directly.
Pool chemicals: frequently asked questions
How does this pool chemical calculator work?
It multiplies your pool volume by the parts-per-million change you want and by the dose rate stated on your product label. The dose rate is the amount of product needed to raise a reference volume by 1 ppm. Because product strengths differ, you read the rate from your label and enter it, so the result matches your exact chemical.
Why do I enter the dose rate myself?
Pool chemicals vary widely in strength: granular chlorine, liquid chlorine, and different alkalinity or pH products each have their own dosing. Hardcoding one figure would be wrong for most products. Reading the dose rate from your product label keeps the calculation accurate and honest for whatever you are using.
How do I find the ppm change I need?
Test your pool water, then subtract the current reading from your target level. For example, if free chlorine reads 1 ppm and you want 3 ppm, the change is 2 ppm. Enter that difference; the calculator multiplies it by your volume and dose rate to find the amount to add.
How do I find my pool volume?
For a rectangular pool, multiply length by width by average depth in feet, then multiply by 7.48 to convert cubic feet to gallons. Many pool tools and your builder's documentation also state the volume. Enter the gallons your pool holds.
Is this a substitute for product instructions?
No. Always follow the safety and dosing instructions on your chemical label and add chemicals gradually, retesting as you go. This calculator helps you compute a starting dose from the label's dose rate, but the manufacturer's directions and local pool safety rules take precedence.
Official sources
- U.S. Centers for Disease Control and Prevention: Healthy swimming and pool disinfection.
- U.S. Environmental Protection Agency: Pool sanitizer product guidance.
Reviewed by the CalculatorHub team, edited by James Graham, 16 June 2026. See our methodology.