Bleach dilution calculator
This bleach dilution calculator scales the CDC recipe for a disinfecting bleach solution to any amount of water. When the bottle has no directions, the CDC says to mix 5 tablespoons (1/3 cup) of bleach per gallon of room-temperature water, or 4 teaspoons per quart. Half a gallon therefore needs 2.5 tablespoons.
Example: Calculate: CDC recipe (5 tbsp per gallon) · Amount of water 1 · Water unit: US gallons · Bleach strength 6 % sodium hypochlorite → Bleach to add: 5.0 tbsp (74 ml) of bleach for 1 gal of water. Source: CDC – Cleaning and Disinfecting with Bleach (page dated April 24, 2024; read 09.10.2026). Updated: .
How it is calculated
CDC ratio: 5 tablespoons of bleach per gallon of water. That is 1 part bleach to 51.2 parts water. The CDC’s quart recipe – 4 teaspoons per quart – is very slightly stronger (1 : 48). The calculator scales the gallon recipe to your amount of water.
Bleach dilution chart (CDC ratio)
| Water | Bleach |
|---|---|
| 1 quart | 1.25 tbsp (3.75 tsp) – CDC rounds to 4 tsp |
| 1 liter | 19.5 ml (about 4 tsp) |
| ½ gallon | 2.5 tbsp |
| 1 gallon | 5 tbsp (1/3 cup, 73.9 ml) |
| 2 gallons | 10 tbsp (5/8 cup) |
With 6 % bleach the CDC gallon mix has about 1149 ppm of sodium hypochlorite; with 8.25 % bleach about 1580 ppm and with 5 % about 958 ppm. Stronger bleach gives a stronger solution – the CDC recipe is meant for regular household bleach of 5–9 %.
How to use the solution (CDC)
- Use regular unscented household bleach and check the label: some laundry or splashless bleach is not meant for disinfection; follow the bottle’s directions if it has them.
- Clean visibly dirty surfaces with soap or detergent first – disinfecting comes after cleaning.
- Make sure there is good ventilation indoors (open windows and doors) and check whether you need gloves or eye protection.
- Mix with room-temperature water.
- Leave the solution on the surface for at least 1 minute; the surface should stay visibly wet.
- Make a fresh solution every day – after 24 hours it is less effective.
- Never mix bleach with any other cleaner or disinfectant (for example ammonia-based glass cleaners) – the vapors can be very dangerous to breathe in.
- Wash your hands afterwards.
Custom strength
Choose “Custom strength” to enter a target in ppm, for example from a product label or a workplace instruction. Bleach = water × target ÷ (strength × 10,000 − target): 1 gallon at 1000 ppm with 6 % bleach needs 4.34 tbsp. The general dilution calculator solves C1V1 = C2V2 for any liquid; for swimming pools use the pool chlorine calculator.
Frequently asked questions
How much bleach per gallon of water to disinfect?
The CDC says 5 tablespoons (1/3 cup) of household bleach per gallon of room-temperature water, if the label gives no directions.
How much bleach per quart or per liter?
4 teaspoons per quart according to the CDC. For a liter the gallon ratio gives 19.5 ml, about 4 teaspoons.
What is the ratio of bleach to water?
The CDC gallon recipe is 1 part bleach to 51.2 parts water; the quart recipe is 1 to 48.
How strong is the solution in ppm?
With 6 % bleach about 1149 ppm, with 8.25 % about 1580 ppm. The calculator shows it for the strength you enter.
How long does diluted bleach last?
Make it fresh every day; the CDC notes it is less effective after 24 hours.
Can I mix bleach with other cleaners?
No. The CDC warns never to mix household bleach with any other cleaner or disinfectant, because this can release vapors that are very dangerous to breathe in. Ammonia-based cleaners are one example.
Sources and legal basis
As of: · Editorial policy
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