Pool Chemical Dosing Calculator
Estimate how much liquid chlorine to raise free chlorine, and how much acid or soda ash to correct pH, for your pool’s exact gallons.
How it works
Liquid chlorine (12.5%): fl oz ≈ ΔFC × (gallons ÷ 10,000) × 10.7 · Soda ash ≈ 4 oz per 0.1 pH per 10,000 gal · Muriatic acid (31%) ≈ 5 fl oz per 0.1 pH per 10,000 gal
Chemical doses scale directly with pool volume, so everything is expressed per 10,000 gallons and multiplied by your actual size. Raising free chlorine with 12.5% liquid chlorine (sodium hypochlorite) takes about 10.7 fluid ounces per part-per-million per 10,000 gallons. pH is trickier because it depends on total alkalinity, so the soda-ash and acid figures here are ballpark starting points — always add chemicals in stages, circulate, and re-test rather than dosing all at once.
Worked example
To raise free chlorine from 1 to 3 ppm (a 2 ppm jump) in a 20,000-gallon pool: 2 × (20,000 ÷ 10,000) × 10.7 = 42.8 fl oz of 12.5% liquid chlorine, about a third of a gallon. To drop pH from 7.8 to 7.5, roughly 5 × 3 × 2 = 30 fl oz of muriatic acid.
Frequently asked questions
How much liquid chlorine raises free chlorine?
About 10.7 fluid ounces of 12.5% liquid chlorine raises free chlorine by 1 ppm in 10,000 gallons. Scale by your pool’s volume and the ppm increase you want, then re-test after the water has circulated.
How do I lower or raise pool pH?
Muriatic acid (or dry acid) lowers pH; soda ash raises it. The exact amount depends heavily on total alkalinity, so add in small doses, run the pump, wait, and re-test rather than dumping the full calculated amount at once.
Is it safe to swim right after dosing?
Wait until chlorine settles back into the 1–4 ppm range and pH is 7.2–7.8, which usually means running the pump for a few hours. Never swim immediately after adding concentrated chemicals, and never mix chemicals together.
Related calculators
Estimates only and dependent on total alkalinity and stabilizer. Add chemicals in stages, follow product labels, never mix chemicals, and re-test before swimming.