Pool Chemical Dose Calculator
Current reading, target reading, gallons. Get the exact amount of each chemical to put in the pool today.
Free. No signup. Works on your phone at the pool.
Not sure? Use the volume calculator
Alkalinity, calcium, stabilizer, salt
Add today
Add acid in two passes: about three quarters of the dose, circulate 30 minutes, retest. Never add acid and chlorine at the same spot at the same time.
Log this reading to the customer's record
Pool Service Log calculates LSI on every stop, saves each reading and dose with a GPS timestamp and photos, and texts the homeowner a service report. When a plaster warranty claim shows up next spring, you have the history.
No credit card. Keep your current billing software.
How the doses are calculated
Chlorine, calcium, alkalinity, stabilizer, and salt are straight stoichiometry: parts per million is milligrams per liter, so the dose is the change in ppm times the pool's liters, divided by the product's active strength.
pH is different. Acid demand depends on how much buffer is in the water, so the calculator models carbonate alkalinity and cyanurate together and solves for the acid or soda ash needed to move from your current pH to the target. That is why a pool at 120 TA needs far more acid than one at 70 for the same pH drop.
Safety
- Pour acid into the deep end with the pump running, low and slow.
- Never mix chlorine and acid, or cal-hypo and trichlor, in a bucket.
- Pre-dissolve cal-hypo and calcium chloride in a bucket of pool water.
Frequently asked questions
How much liquid chlorine raises a pool 1 ppm?▼
About 12.8 fl oz of 10% liquid chlorine, or 10.2 fl oz of 12.5%, raises 10,000 gallons by 1 ppm. The calculator scales that to your pool volume and target.
How much muriatic acid do I need to lower pH?▼
It depends on alkalinity and CYA, not just pH. Higher alkalinity means more buffer and more acid for the same drop. The calculator models the carbonate and cyanurate buffers directly, so enter your current TA and CYA for an accurate number.
Why add acid in two passes?▼
Test kits, volume estimates, and product strength all carry some error. Adding about three quarters of the dose, circulating for 30 minutes, and retesting keeps you from overshooting and chasing pH back up with soda ash.
Soda ash or baking soda to raise pH?▼
Soda ash raises pH strongly and alkalinity somewhat. Baking soda raises alkalinity strongly and pH only slightly. If pH and TA are both low, start with baking soda for TA, then retest pH.
What strength muriatic acid does the calculator assume?▼
Standard 31.45% hydrochloric acid, the common 20 Baumé product. If you use a 14.5% low-fume acid, roughly double the listed amount.
More free pool tools
LSI Calculator
Langelier Saturation Index with CYA-corrected alkalinity. Corrosive, balanced, or scaling in one tap.
CYA Drain Calculator
How much water to drain and refill to bring stabilizer, hardness, or salt back down.
Pool Volume Calculator
Gallons for rectangle, round, oval, and kidney pools from a tape measure.