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Short answer: the percentage printed on a bleach bottle is the share of the product that is sodium hypochlorite, and CDC describes household bleach as 5.25%-6.15% sodium hypochlorite, which it equates to 52,500-61,500 ppm available chlorine. A bottle can print a different number, such as 7.5%, and it can also print a separate “available chlorine” figure that is lower than the hypochlorite percentage. What the product is allowed to be used for is set by its directions and EPA registration number, not by the name on the front. This page covers how to read those numbers; it gives no dilution steps (see the 10% bleach solution guide for those) and is general information, not safety advice for a specific task.
Definition and scope
“Bleach concentration” can mean three different things on the same bottle or in the same protocol, and mixing them up is the most common source of confusion.
- Percent sodium hypochlorite: the concentration of the active ingredient in the product as sold. CDC’s Disinfection and Sterilization Guidelines describe household bleach as “aqueous solutions of 5.25%–6.15% sodium hypochlorite”.
- Available chlorine: a measure of the oxidizing capacity, expressed as a percentage or in parts per million (ppm). CDC states that household bleach contains 5.25%-6.15% sodium hypochlorite, “or 52,500–61,500 ppm available chlorine”.
- Dilution ratio or working-solution strength: what a protocol asks you to prepare from the product (for example “1:10”). CDC lists a 1:10-1:100 dilution of 5.25%-6.15% sodium hypochlorite as the household-bleach range, and notes that a 1:1,000 dilution provides about 53-62 ppm available chlorine. The recipe for a given task belongs in a method, not on a product page.
How the numbers appear on a real EPA-accepted label
The U.S. EPA accepted the label for a 7.5% sodium hypochlorite product (EPA Reg. No. 55852-6, label accepted 23 January 2023). Its active-ingredient block reads “Sodium Hypochlorite … 7.5%” with “Other Ingredients … 92.5%”, and a separate line reads “[Available Chlorine 7.13%]”. The two figures describe the same product in two different ways, so a protocol that says “use X% bleach” is ambiguous unless it says which one it means.
| What to read on the label | Example from the EPA-accepted 7.5% label (Reg. No. 55852-6) | Comparison point from CDC |
|---|---|---|
| Percent sodium hypochlorite | 7.5% | Household bleach: 5.25%-6.15% |
| Available chlorine line | 7.13% (a separate figure from the 7.5%) | 5.25%-6.15% hypochlorite = 52,500-61,500 ppm available chlorine |
| EPA registration number | 55852-6 (two parts separated by a dash) | Not applicable |
| Product names listed on the label | “Disinfecting Laundry Bleach”, “Germicidal Bleach”, “Cleaning Bleach”, “Ultra Bleach”, “Sanitizer” | Not applicable |
| Mixing warning | “Mixing this product with chemicals (e.g., ammonia, acids, detergents, etc.) … may release chlorine gas” | Not applicable |
| Storage | Cool dry area, away from direct sunlight and heat, to avoid deterioration | Not applicable |
Using the same 1% = 10,000 ppm relationship that CDC’s pair of figures implies (5.25% = 52,500 ppm), an available-chlorine figure of 7.13% corresponds to about 71,300 ppm. That is higher than the household-bleach range CDC gives, so a 7.5% product is not interchangeable with the CDC baseline when a protocol is written around 5.25%-6.15%. This is arithmetic on the cited figures, not a statement from either source. The label is an EPA-accepted template, so bracketed optional text on it should not be read as applying to every bleach product.
Disinfecting versus laundry wording, and the EPA registration number
The same registered label lists several marketing names, including “Disinfecting Laundry Bleach” and “Germicidal Bleach”, and the EPA letter attached to it concerns efficacy data supporting disinfection, fungi, virus and laundry-sanitizer claims. The name therefore tells you little by itself. The claims a product may make are in its label directions, which is where use sites are listed: for this label, hard non-porous surfaces in commercial, institutional, hospital and household premises, plus a laundry-sanitizer claim, with dilution “as stated in directions below”.
EPA’s page on selected EPA-registered disinfectants states that each label has a registration number that is a unique identifier of the product, that “the only way to accurately identify a product is by the EPA registration number”, and that the number is found on the label affixed to the container, in two or three parts separated by dashes. The practical reading for a stockroom is to record the registration number and read the directions for the intended use, rather than matching on a product name or on the percentage alone.
Where it matters for labs, clinics and supply decisions
- Two products with different labels are different inputs. A protocol written for household bleach at 5.25%-6.15% hypochlorite does not automatically transfer to a product labelled 7.5%, because the active-ingredient percentage and the available-chlorine figure differ (see the table above).
- Record the registration number, not just the brand. EPA identifies a disinfectant by that number, so it is the identifier to put on an approved-products list or SOP.
- High concentrations are corrosive. CDC lists “corrosiveness to metals in high concentrations (>500 ppm)” among the limits of hypochlorites; the 7.5% label likewise warns that prolonged contact with metal may cause pitting or discoloration. Material compatibility is covered in the surface disinfectant selection guide.
- Organic matter reduces activity. CDC lists inactivation by organic matter among the limits and notes that hypochlorites are substantially inactivated in the presence of blood.
- Never combine with other chemicals. The label warns that mixing with ammonia, acids or detergents may release chlorine gas. Chemical-hazard documentation duties are outlined in the written hazard communication program guide.
- Storage affects the product. The label directs storage in a cool, dry area away from direct sunlight and heat to avoid deterioration.
For how bleach sits among other disinfectant classes, see types of disinfectants.
Common misunderstandings
“10% bleach” means 10% sodium hypochlorite
In protocols, “10% bleach” is normally a dilution of the household product, not a solution that is 10% sodium hypochlorite. The guide on making a 10% bleach solution explains that usage. The label percentage on the bottle is the product as sold.
The percentage and the available chlorine are the same number
On the EPA-accepted 7.5% label they are not: 7.5% sodium hypochlorite and 7.13% available chlorine appear as separate figures.
The product name shows what it is approved for
The same label lists names from “Cleaning Bleach” to “Germicidal Bleach” to “Sanitizer”. EPA identifies a product by its registration number, and the directions define the claims.
FAQ
What concentration is household bleach?
CDC describes household bleach as 5.25%-6.15% sodium hypochlorite, or 52,500-61,500 ppm available chlorine (CDC, checked 30 October 2026).
Is sodium hypochlorite concentration the same as available chlorine?
Not necessarily. The EPA-accepted label for a 7.5% sodium hypochlorite product lists available chlorine separately as 7.13%.
How do I tell whether a bleach is a registered disinfectant?
Look for the EPA registration number on the container label. EPA states it is the only accurate way to identify a product, and it has two or three parts separated by dashes.
Does this page give dilution instructions?
No. Working-solution recipes and contact times belong in a validated method; see the linked guides and the product’s own label directions.
Sources
- CDC, Chemical Disinfectants (Disinfection and Sterilization Guidelines), checked 30 October 2026.
- U.S. EPA, accepted product label, Sodium Hypochlorite 7.5%, EPA Reg. No. 55852-6 (23 January 2023), checked 30 October 2026.
- U.S. EPA, Selected EPA-registered disinfectants, checked 30 October 2026.
