Pool Chemical Calculator
Enter your test readings. The result says whether each one sits inside a cited range. It does not tell you how many ounces of pH or alkalinity product to add.
Result: readings
Free chlorine 3 ppm: in the CDC home pool range of 1 to 4 ppm.
pH 7.4: in the MAHC range of 7.0 to 7.8.
Total alkalinity 100 ppm: in the MAHC annex range of 60 to 180 ppm.
Calcium hardness 300 ppm: in the MAHC annex band of 200 to 400 ppm for concrete or plaster.
Cyanuric acid 40 ppm: at or under the MAHC maximum of 90 ppm.
Combined chlorine 0.2 ppm: at or under the MAHC annex ceiling of 0.4 ppm.
This page does not compute a pH or alkalinity dose. Those product amounts are not verified.
Source: CDC. Use of CDC information does not imply endorsement by CDC.
Follow the product label.
Chemical safety: read before you add anything
- Never mix pool chemicals together, in or out of the water. Add each one separately.
- Never mix chlorine with acid. Never mix cal-hypo (calcium hypochlorite) with trichlor.
- Add acid to water. Never pour water into acid.
- Split large doses into smaller portions. A numeric per-dose limit is not verified.
- This result is an estimate. Follow the product label.
What Pool Chemical Levels Do You Need?
Free chlorine on the CDC home page is 1 to 4 ppm. The code minimum is 1.0 ppm without cyanuric acid and 2.0 ppm with it. The open-water maximum is 10.0 ppm. pH in the code is 7.0 to 7.8, and the annex discusses 7.2 to 7.6 where Langelier balance is the topic.
A dose for pH increaser, pH decreaser, or alkalinity product is not verified on this site. Use the chlorine calculator for a free-chlorine dose, and follow the label for everything else.
The example readings in the form (free chlorine 3, pH 7.4, alkalinity 100, hardness 300 on concrete, cyanuric acid 40, combined chlorine 0.2) are an in-range illustration, not a target you must hit.
Cited Pool Chemical Ranges
| Reading | Cited figure | Where it comes from |
|---|---|---|
| Free chlorine, home page | 1 to 4 ppm | CDC home pool page |
| Free chlorine minimum, no cyanuric acid | 1.0 ppm | MAHC |
| Free chlorine minimum, with cyanuric acid | 2.0 ppm | MAHC |
| Free chlorine maximum while open | 10.0 ppm | MAHC |
| pH | 7.0 to 7.8 | MAHC |
| pH band in the Langelier annex note | 7.2 to 7.6 | MAHC annex |
| Total alkalinity | 60 to 180 ppm | MAHC annex |
| Total alkalinity, Pentair IntelliChlor guide | 80 to 120 ppm | Pentair, not the code |
| Calcium hardness, concrete or plaster | 200 to 400 ppm | MAHC annex |
| Calcium hardness, vinyl or fiberglass | 80 to 200 ppm | MAHC annex |
| Calcium hardness above 90 F | 100 to 200 ppm | MAHC annex |
| Cyanuric acid maximum | 90 ppm | MAHC |
| Cyanuric acid band in the Pentair guide | 30 to 50 ppm | Pentair, citing APSP |
| Cyanuric acid to free chlorine at closure | 45 to 1 | MAHC |
| Combined chlorine ceiling | 0.4 ppm | MAHC annex |
| Cyanuric acid from dichlor | 0.9 ppm per 1 ppm free chlorine | PHTA dichlor bulletin |
| Cyanuric acid from trichlor | Not verified | No number is shown |
Source: CDC, 2023 Model Aquatic Health Code (MAHC), §5.7.3.4.1. No CDC endorsement implied; available free at cdc.gov. Per Pentair IntelliChlor user's guide.
Common Mistakes With the Pool Chemical Calculator
- Treating the Pentair 80 to 120 alkalinity band as if it were the code. The annex range is 60 to 180 ppm.
- Expecting an ounce count for pH down. That dose is not verified here.
- Using one hardness band for every surface. Concrete, vinyl, and hot water are different rows.
Free Chlorine Dose: Use the Chlorine Calculator
The chlorine calculator works out a free-chlorine dose from your pool's gallons and the product you pick.
Pool Chemical Calculator FAQ
What pH range does the MAHC require?
7.0 to 7.8. Source: CDC, 2023 Model Aquatic Health Code (MAHC), §5.7.3.4.1. No CDC endorsement implied; available free at cdc.gov. Follow the product label.
What is the combined chlorine ceiling in the MAHC annex?
0.4 ppm. Source: CDC, 2023 Model Aquatic Health Code (MAHC), §Annex 5.7.3. No CDC endorsement implied; available free at cdc.gov. Follow the product label.
Will this page tell you how many ounces of pH increaser to add?
No. A dose for pH or alkalinity products is not verified here. Follow the product label.
What is the closure ratio of cyanuric acid to free chlorine?
45 to 1. Source: CDC, 2023 Model Aquatic Health Code (MAHC), §6.6.3.1. No CDC endorsement implied; available free at cdc.gov. Follow the product label.