Pool Chemical Unit Converter (Ounces, Cups, Pounds, ppm)
1 lb of baking soda is about 2.05 level cups, or 32.9 tablespoons, based on 4.6 g per level teaspoon. For liquids, 1 cup is 8 fl oz, a gallon is 128 fl oz, and 1 ppm in water is the same as 1 mg per liter.
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
On this page (7 sections)
Pool doses come in many units: fluid ounces of liquid chlorine, pounds of baking soda, grams of dichlor, ppm on the test kit. This converter turns one into another so you can measure with what you have.
Calculator: ounces, cups, pounds, and metric
Enter an amount, its unit, and the product. The example is 1 lb of baking soda. The calculator shows it as 98.6 teaspoons, 32.9 tablespoons, 2.05 cups, 16.4 fl oz, 0.51 quarts, 0.13 gallons, 486 mL, or 0.49 L of powder, and as 16 oz, 454 g, or 0.45 kg by weight.
The US kitchen measures are exact (NIST): 1 cup = 8 fl oz = 16 tablespoons = 48 teaspoons. A tablespoon is 1/2 fl oz and a teaspoon is 1/6 fl oz. Use level spoons and cups, not heaped ones.
Fluid ounces are not ounces of weight
The word "ounce" means two different things:
- Fluid ounces (fl oz) measure volume. Liquid chlorine, bleach, and muriatic acid doses are in fl oz.
- Ounces (oz) on a bag of powder measure weight. 16 oz = 1 lb.
For water, 1 fl oz weighs a little over 1 oz, so mixing them up makes little difference. For powders, the error can be large: a fluid ounce of a light powder weighs much less than an ounce. That is why the calculator needs to know the product before it turns weight into cups.
Powders: why we ask you to weigh a cup
How much a level cup of powder weighs depends on the grain size and how tightly it packs. We have a sourced figure for only two products:
- Baking soda: 4.6 g per level teaspoon, from the U.S. Department of Agriculture's FoodData Central.
- Dichlor: about 5 g per level teaspoon, the figure our calculators use. Granule size varies by brand.
For other powders, such as cal hypo, pool salt, stabilizer (cyanuric acid), calcium chloride, soda ash, or dry acid, we could not confirm reliable figures. Choose "Other" and enter your own grams per level cup: set an empty cup on a kitchen scale, zero it, fill the cup level with the product, and read the grams. Use a cup kept only for pool chemicals.
The most accurate way is still to weigh the dose itself. The baking soda calculator and the dichlor calculator give doses by weight and in cups or spoons.
Liquid chlorine: fluid ounces, cups, and gallons
Our chlorine calculators give liquid doses in fl oz. To pour with a measuring cup, divide fl oz by 8. A gallon jug holds 128 fl oz, so a dose of more than 128 fl oz is more than one full gallon jug.
Get the dose itself from the liquid chlorine calculator, which accounts for your bottle's strength (for example, 10% or 12.5%). Bottles of different strengths need different amounts, so never swap strengths without recalculating. Always follow the product label.
Safety. Use separate, labeled measuring cups for each pool chemical, and never use them for food. Never mix chlorine with acid or with other chemicals, in the cup or in the pool. Add chemicals to water, not water to chemicals. Wear gloves and eye protection. See pool chemical safety. If someone swallows a pool chemical, call Poison Control at 1-800-222-1222.
ppm, mg/L, gallons, and liters
- ppm = mg/L. In pool water, 1 part per million (ppm) is the same as 1 milligram per liter. Test kits and labels use them the same way.
- Gallons to liters. 1 US gallon = 3.785 liters.
- Cubic meters. 1 cubic meter = 1,000 liters.
The pool chemical calculator takes your pool size in gallons or liters.
FAQ
How many cups of liquid chlorine should I add to my pool?
First get the dose in fl oz from the liquid chlorine calculator for your pool size and bottle strength, then divide by 8 to get cups. The amount depends on your gallons, how far you want to raise chlorine, and the strength on the label. Always follow the product label.
How many ounces are in a gallon of chlorine?
128 fl oz. A US gallon is 128 fluid ounces, or 16 cups, for any liquid. That is volume, not weight.
Is ppm the same as mg/L?
Yes, for pool water. 1 ppm equals 1 milligram per liter, so a reading of 3 ppm chlorine is 3 mg/L.
How many cups are in a pound of baking soda?
About 2.05 level cups, or 32.9 tablespoons, based on the USDA figure of 4.6 g per level teaspoon. Weigh it if you can, since packing changes the volume a little.
Sources
- NIST, Metric kitchen: cooking measurement equivalencies (cup, tablespoon, teaspoon in fluid ounces): nist.gov
- NIST Handbook 44, Appendix C, General tables of units of measurement (gallon, fluid ounce, liter): nist.gov
- USDA FoodData Central, Leavening agents, baking soda, FDC ID 175040 (1 tsp = 4.6 g; search the ID on the site): fdc.nal.usda.gov
- Dichlor spoon weight and unit constants: methodology