Pool Chemical Dosage Calculator
Target minus current reading.
Baking soda (sodium bicarbonate) to add
4.2 lb
Add 4.2 lb of baking soda (sodium bicarbonate) to raise total alkalinity by 20 ppm in 15,000 gallons.
- Changes
- total alkalinity (up)
- Strength used
- 100%
- Rate
- 1.4 lb per 10,000 gal per 10 ppm
- Never mix pool chemicals with each other, wet or dry.
- Always add chemicals to water, never water to chemicals.
- Follow the manufacturer's label. It overrides any calculator, including this one.
How it's calculated
Every dose follows the same mass balance; only the chemistry factor changes with the product:
| Product | Changes | Factor per ppm |
|---|---|---|
| Chlorine products | Free chlorine | 1 mg available chlorine per liter |
| Baking soda | TA up | 84.0 ÷ 50.04 = 1.68 mg/L |
| Soda ash | TA up (and pH) | 106.0 ÷ 100.1 = 1.06 mg/L |
| Muriatic / dry acid | TA down (and pH) | 1 mol acid per 50,044 mg of TA |
| Calcium chloride | Calcium hardness up | 111.0 ÷ 100.1 = 1.11 mg/L |
| Stabilizer, salt | CYA, salt up | 1 mg/L |
The factors are ratios of molar masses, because alkalinity and hardness are reported "as calcium carbonate". pH is not on this list on purpose: how much acid moves pH depends on alkalinity, so it has its ownpH calculator.
Worked example
Raise total alkalinity by 20 ppm in a 15,000 gallon pool with baking soda:
- Volume: 15,000 × 3.785 = 56,781 liters.
- Baking soda: 20 × 56,781 × 1.68 = 1,906,349 mg.
- In ounces: ÷ 28,350 = 67 oz, or 4.2 lb.
Dose per 10,000 gallons by product
| Product | Effect | Amount |
|---|---|---|
| Liquid chlorine 12.5% | free chlorine +1 ppm | 10.2 fl oz |
| Liquid chlorine 10% | free chlorine +1 ppm | 12.8 fl oz |
| Household bleach 8.25% | free chlorine +1 ppm | 15.5 fl oz |
| Household bleach 6% | free chlorine +1 ppm | 21.3 fl oz |
| Cal-hypo 65% | free chlorine +1 ppm | 2.05 oz |
| Cal-hypo 73% | free chlorine +1 ppm | 1.83 oz |
| Dichlor 56% | free chlorine +1 ppm | 2.38 oz |
| Trichlor 90% | free chlorine +1 ppm | 1.48 oz |
| Baking soda (sodium bicarbonate) | total alkalinity +10 ppm | 1.4 lb |
| Soda ash (sodium carbonate) | total alkalinity +10 ppm | 14.1 oz |
| Muriatic acid 31.45% | total alkalinity −10 ppm | 25.6 fl oz |
| Muriatic acid 14.5% (low-fume) | total alkalinity −10 ppm | 1.88 qt |
| Dry acid (sodium bisulfate 93.2%) | total alkalinity −10 ppm | 2.15 lb |
| Calcium chloride 77% (flakes) | calcium hardness +10 ppm | 1.2 lb |
| Calcium chloride 94% (anhydrous) | calcium hardness +10 ppm | 15.8 oz |
| Stabilizer (cyanuric acid) | CYA (stabilizer) +10 ppm | 13.4 oz |
| Pool salt (sodium chloride) | salt +100 ppm | 8.35 lb |
Frequently asked questions
How do I calculate pool chemical dosage?
Multiply the change you want (in ppm, which equals mg per liter) by the pool volume in liters to get milligrams of the active ingredient, then divide by the product strength and convert to ounces or pounds. This calculator does that for every common product.
What order should I add pool chemicals in?
Usually alkalinity first, then pH, then calcium, then stabilizer, then chlorine. Add one product at a time, let it circulate (several hours for alkalinity and calcium), retest, and never add two chemicals at the same spot or time.
Can I add all the chemicals at once?
No. Some combinations react dangerously, for example acid with chlorine releases chlorine gas, and cal-hypo with trichlor can catch fire. Add each product separately to the water, with the pump running, and wait between them.
Why is the dose different from the product label?
Labels usually assume a 10,000 gallon pool and a standard starting point. This calculator uses your exact volume, the change you need and the product strength you enter. If your result differs a lot from the label, double-check the volume.
How accurate is a pool chemical calculator?
The math is exact; the uncertainty is in the inputs. Pool volume estimates are often off by 10% or more, test strips can be off by a full color step, and liquid chlorine loses strength with age. Add most of the dose, circulate, retest and finish.
Related calculators
- Pool Chlorine CalculatorDose for liquid, cal-hypo, dichlor or trichlor.
- Pool pH CalculatorAcid or soda ash to hit your target pH.
- Pool Alkalinity CalculatorBaking soda to raise TA, acid to lower it.
- Pool Calcium Hardness CalculatorCalcium chloride to raise CH, or drain to lower it.
- Pool Stabilizer (CYA) CalculatorStabilizer to add, or water to drain to lower CYA.
See all Pool Water Chemistry Calculators.