How much chlorine to add to your pool
Add about 1 fl oz of 12.5% liquid chlorine per 1,000 gallons for each 1 ppm of free chlorine (FC) you need.
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.
| Pool size | Pool liquid chlorine 12.5% | Pool liquid chlorine 10% | Household bleach 6% | Household bleach 8.25% |
|---|---|---|---|---|
| 500 gal | 0.5 fl oz15 mL | 0.6 fl oz19 mL | 1.0 fl oz30 mL | 0.7 fl oz21 mL |
| 1,000 gal | 1.0 fl oz30 mL | 1.3 fl oz38 mL | 2.1 fl oz61 mL | 1.4 fl oz43 mL |
| 2,000 gal | 2.0 fl oz61 mL | 2.6 fl oz76 mL | 4.1 fl oz122 mL | 2.9 fl oz86 mL |
| 3,000 gal | 3.1 fl oz91 mL | 3.8 fl oz114 mL | 6.2 fl oz183 mL | 4.3 fl oz129 mL |
| 4,000 gal | 4.1 fl oz121 mL | 5.1 fl oz151 mL | 8.2 fl oz244 mL | 5.8 fl oz172 mL |
| 5,000 gal | 5.1 fl oz151 mL | 6.4 fl oz189 mL | 10 fl oz305 mL | 7.2 fl oz214 mL |
| 6,000 gal | 6.1 fl oz182 mL | 7.7 fl oz227 mL | 12 fl oz366 mL | 8.7 fl oz257 mL |
| 7,000 gal | 7.2 fl oz212 mL | 9.0 fl oz265 mL | 14 fl oz427 mL | 10 fl oz300 mL |
| 8,000 gal | 8.2 fl oz242 mL | 10 fl oz303 mL | 16 fl oz488 mL | 12 fl oz343 mL |
| 10,000 gal | 10 fl oz303 mL | 13 fl oz379 mL | 21 fl oz609 mL | 14 fl oz429 mL |
| 12,000 gal | 12 fl oz363 mL | 15 fl oz454 mL | 25 fl oz731 mL | 17 fl oz515 mL |
| 15,000 gal | 15 fl oz454 mL | 19 fl oz568 mL | 31 fl oz914 mL | 22 fl oz643 mL |
| 20,000 gal | 20 fl oz606 mL | 26 fl oz757 mL | 41 fl oz1.22 L | 29 fl oz858 mL |
| 25,000 gal | 26 fl oz757 mL | 32 fl oz946 mL | 52 fl oz1.52 L | 36 fl oz1.07 L |
| 30,000 gal | 31 fl oz908 mL | 38 fl oz1.14 L | 62 fl oz1.83 L | 43 fl oz1.29 L |
| 40,000 gal | 41 fl oz1.21 L | 51 fl oz1.51 L | 82 fl oz2.44 L | 58 fl oz1.72 L |
Multiply by how many ppm you need. Example: FC 1 → 4 is +3 ppm. Each size links to its full dose chart.
On this page (9 sections)
Aim for the target that fits your stabilizer (CYA), usually 3–5 ppm FC. For the same 1 ppm per 1,000 gallons, other products take about 1.3 fl oz of 10% liquid chlorine, 2.1 fl oz of 6% bleach, 0.21 oz of 65% cal-hypo, or 0.15 oz of 90% trichlor. Multiply by your thousands of gallons and the ppm you need.
Calculator: pool size, current FC, target FC, your product
A general answer stops at "per 1,000 gallons". Your dose needs four of your own numbers: pool volume, how far you are from the target, which product you use, and its strength. The calculator starts at a 10,000-gallon pool going from FC 1 to 4 ppm with 12.5% liquid chlorine. Change any field and the amount updates.
- Your stabilizer (CYA) reading sets the minimum and target for you, so you can see whether your goal is too low or too high.
- If your label shows a different percentage (for example, 8.25% bleach or 73% cal-hypo), type it into the strength field.
- Powders and tablets are shown in ounces or pounds by weight, and liquids in fluid ounces or gallons. Switch to metric for mL and grams.
Only using liquid chlorine? The liquid chlorine calculator adds a "strength left" field for jugs that have aged. Using household bleach? Go to the bleach calculator.
Chart: ounces per 1 ppm for common products and pool sizes
The table above lists the amount that raises FC by 1 ppm in pools from 500 to 40,000 gallons, for the two pool chlorine strengths and two bleach strengths. To use it:
- Subtract your current FC from your target. For example, going from FC 1.5 to 4.5 is +3 ppm.
- Find your pool size (or the nearest row) and your product.
- Multiply. For 15,000 gallons and 10% liquid chlorine: 19 fl oz × 3 = about 58 fl oz.
Dry products for the same +1 ppm in 10,000 gallons: 2.1 oz of 65% cal-hypo, 2.4 oz of 56% dichlor, and 1.5 oz of 90% trichlor. Click any pool size in the table for its full dose sheet: shock, acid, baking soda, stabilizer, and salt on one page.
Online answers for the same pool size often look contradictory. For 15,000 gallons, we saw 31 fl oz, 39 fl oz, and "1.5 gallons a week". Each one assumes a different product strength or ppm change, as the breakdown on the 15,000-gallon pool page shows.
What target to aim for (it depends on your CYA)
"1 to 3 ppm" is fine only for water with no stabilizer. Stabilizer (cyanuric acid, CYA) holds part of your chlorine in reserve, so the level you need rises with it:
- CYA 0: target 2–4 ppm
- CYA 30: target 2.5–4.5 ppm
- CYA 40: target 3–5 ppm
- CYA 50: target 4–6 ppm
Most pool chlorine labels say not to swim above 4 ppm, and the CDC model code sets 10 ppm as the upper limit. Holding CYA at 30–40 ppm keeps your target under both. The reasoning, and the numbers for salt water pools, are on the ideal pool chlorine level page.
Do pools need chlorine every day?
Yes, most outdoor pools need chlorine every day or every other day, because they lose it every day. The amount is what varies: add as much as your pool loses. Sun, heat, rain, leaves, and swimmers all use up chlorine, and the rate differs from pool to pool and week to week. The practical way to find yours:
- Test FC at the same time every day for three or four days without shocking.
- Your daily loss is the average drop per day.
- Your daily dose is that loss × the "per 1 ppm" amount for your pool and product.
If you only add chlorine once or twice a week, you have to start high enough that FC never drops below your minimum before the next dose. That is why weekly-only routines tend to swing between too much and too little. The CDC advises home pool owners to "test chlorine concentration and pH at least twice per day." Many liquid chlorine users add it in the evening, so it has a full night before sunlight starts to break it down. If your chlorine keeps disappearing even with a normal dose, read why chlorine won't hold. For a weekly routine, see the pool maintenance schedule.
Can you swim right after adding chlorine?
Test first. The label decides. Most pool chlorine labels say not to swim above 4 ppm free chlorine. After a normal daily dose that keeps FC at or below that limit, give the chlorine time to mix: our calculators use 30 minutes with the pump running between products. Then test. If FC is above the limit on your product's label, wait and retest. Sunlight and time bring it down. Hot tubs have their own limit, often 4 ppm on spa labels (see hot tub chlorine).
Side effects: tablets add CYA, cal-hypo adds calcium
Every chlorine product adds something besides chlorine. The dose is the easy part. The by-products add up over a season (per 1 ppm of FC added; PHTA figures for trichlor and dichlor):
- Trichlor tablets: +0.6 ppm CYA, and they lower total alkalinity (TA) as the chlorine is used up.
- Dichlor granules: +0.9 ppm CYA.
- Cal-hypo: about +0.7 ppm calcium hardness.
- Liquid chlorine and bleach: no CYA and no calcium, but they add a little salt.
Example: a pool that loses 2 ppm a day and runs only on trichlor gets about 8.4 ppm more CYA every week. In five weeks that is +42 ppm, which pushes the chlorine you need above what a swimming label allows. Pools on tablets often switch to liquid chlorine mid-season for that reason. Compare the options in types of pool chlorine, and see how fast tablets add CYA with the chlorine tablets calculator. For a full test with pH and alkalinity too, use the pool chemical calculator.
Details for pool technicians
- Formula. Available chlorine needed (g) = ΔFC (ppm) × liters ÷ 1,000. 1 ppm in 1,000 gallons (3,785 L) = 3.785 g.
- Liquid chlorine is labeled in trade percent: 10% = 100 g/L of available chlorine, 12.5% = 125 g/L. 3.785 g ÷ 100 g/L = 37.9 mL = 1.28 fl oz.
- Bleach is labeled by weight of sodium hypochlorite, so 6% bleach contains about 62 g/L of available chlorine, not 60. That is why it takes 2.06 fl oz, not 2.13.
- Dry products use the available chlorine percent on the label: 65% cal-hypo, 56% dichlor, 90% trichlor. The full method is on the methodology page.
Safety. Never mix different chlorine products, and never let chlorine touch acid: together they release chlorine gas. Add chlorine to the pool water, not water to the chlorine, with the pump running. Wear gloves and eye protection. Always follow the product label. If someone swallows chlorine or gets it in their eyes, call Poison Control at 1-800-222-1222.
FAQ
Is it bad to add too much chlorine to a pool?
Yes, for swimmers and for the pool. Above your target, the water can irritate eyes and skin and bleach swimwear and liners. Pool labels usually say not to swim above 4 ppm. Above 10 ppm, the CDC model code says no swimming. It isn't permanent: sunlight and time bring chlorine down, faster in direct sun with the cover off. Wait, retest, and don't add anything to "neutralize" it unless you know why. See chlorine too high.
Is 2 gallons of chlorine too much?
For most home pools, yes. 2 gallons of 10% liquid chlorine raises FC by about 20 ppm in 10,000 gallons and about 13 ppm in 15,000 gallons, far above the 4 ppm swim limit on most labels. Even in a 30,000-gallon pool it adds about 6.7 ppm. Dose from your own test with the calculator above, and use larger amounts only as your product's label directs.
Sources
- CDC, Home pool and hot tub water treatment and testing: cdc.gov
- CDC, Model Aquatic Health Code 2024, Annex: cdc.gov (PDF)
- Taylor Technologies, K-1005 treatment tables: PDF
- PHTA fact sheets, Sodium hypochlorite and Dichlor: phta.org, phta.org
- Google results for "how much chlorine for 15000 gallon pool", checked 2026-09-29 (our notes, not linked).