Free Pool Chemical Calculators
Pool chemistry is a system — these calculators cover each piece of it. Start with your pool volume, then work through chlorine, pH, and water balance.
Pool chemical calculators take the guesswork out of dosing. Back-of-bag instructions assume an average pool — these tools use your actual pool volume, current readings, and target values to give you an exact dose. Start with the pool volume calculator; every other calculation on this page depends on knowing your pool size.
Start here
Every other calculator on this page needs your pool volume. Find it once and the rest of the math follows.
Chlorine Management
Chlorine only works if your dose matches your CYA and pool volume — these calculators do that math.
Chlorine Dose Calculator
How much liquid chlorine or cal-hypo to add to reach your target FC. Supports 10%, 12.5%, cal-hypo 65%/73%, and trichlor.
Pool Shock Calculator
Find your shock target (CYA × 40%) and how much chlorine to reach it. The shock level depends on your CYA — not a fixed number.
Chlorine Cost Calculator
Compare the true seasonal cost of liquid chlorine, trichlor tablets, and cal-hypo — including the hidden CYA drain cost that tablets don't show on the label.
OCLT Calculator
Enter your dusk and dawn FC readings to get an instant pass/fail verdict — and find out whether your pool has an algae demand problem before closing for winter.
pH & Alkalinity
pH controls how effective your chlorine is. Alkalinity buffers pH against swings. Keep both in range and the rest of pool chemistry gets much easier.
Pool pH Calculator
Raise or lower pool pH — muriatic acid to bring it down, soda ash to bring it up. Enter pool volume, current pH, and target.
Muriatic Acid Calculator
How much muriatic acid to lower pH or total alkalinity. Supports 31.45% and 14.5% strengths.
Baking Soda Calculator
How much baking soda to raise total alkalinity to target. TA is your pH's buffer — too low and pH swings with every addition.
Dry Acid to Muriatic Acid Calculator
Convert between dry acid (sodium bisulfate) and muriatic acid — find the equivalent dose for any amount or product strength.
CYA (Stabilizer)
CYA protects chlorine from UV, but once it's in the water the only way out is dilution. This calculator tells you exactly how much to drain.
Water Balance & Hardness
Unbalanced water corrodes equipment and etches surfaces over time. LSI is the standard measure — calcium hardness is one of its key inputs.
LSI Calculator
Calculate your Langelier Saturation Index using the full formula — CYA-corrected alkalinity, polynomial temperature factor, and a factor breakdown showing exactly what's driving your water balance score.
Calcium Hardness Calculator
How much calcium chloride to raise CH to target. Supports 77% flake and 96% anhydrous. CH affects LSI — low CH is corrosive, high CH causes scaling.
Seasonal
Closing and opening your pool is a one-shot job each season — get the chemistry right the first time with the right products in the right order.
Saltwater Pools
Salt chlorine generators need a precise salt level to operate. This calculator tells you exactly how many pounds to add.
Frequently asked questions
Which pool calculator should I use first?
Start with the pool volume calculator. Every dose calculator on this page — chlorine, shock, muriatic acid, baking soda, calcium hardness, and salt — needs your pool's gallon count as an input. Find your volume once and the rest of the math follows.
How do I calculate how much chlorine to add to my pool?
Use the chlorine dose calculator. Enter your pool volume, current free chlorine (FC) reading, and target FC. The calculator supports liquid chlorine (10% and 12.5% sodium hypochlorite), calcium hypochlorite (cal-hypo 65% and 73%), and trichlor tablets.
How much shock does my pool need?
Shock level is CYA × 40% — it is not a fixed number. At CYA 50 ppm, shock level is 20 ppm FC. At CYA 80, it is 32 ppm FC. The pool shock calculator computes the exact dose for your pool volume and CYA.
How much muriatic acid do I need to lower pool pH?
Use the muriatic acid calculator. Enter your pool volume, current pH, and target pH (7.4–7.6 is the standard range). The calculator supports 31.45% full-strength and 14.5% diluted muriatic acid, and also handles alkalinity reduction.
Are these pool calculators free?
Yes — all calculators on this page are completely free to use. No account, no sign-up, and no app required.