Bleach Dilution Calculator
Bleach dose and ratio for 100, 1000, or 5000 ppm mixes.
What it does
Bleach disinfects only at the right dilution: too weak leaves germs, too strong ruins surfaces and wastes chemical. Target strengths cluster at 100 ppm for sanitizing, 1,000 ppm for disinfection, and 5,000 ppm for heavy soil work.
The tool above takes the target, the bottle percent, and the water volume in gallons or liters. It returns the bleach dose, the parts ratio, and the ppm check.
The default gallon at 1,000 ppm from 6% stock needs 12.8 tsp (2.1 fl oz), a 1 to 59 mix. The metric mirror of 3.79 L needs 63.2 mL at the same ratio.
CDC Appendix E states the parts rule with a worked 0.5% example, and household guidance bounds stock at 5% to 9%. Ready.gov adds the emergency drinking water cousin: 1/8 tsp per gallon of 5.25 to 6.0% bleach with a 30 minute stand.
Fresh mix matters as much as correct math. Diluted bleach fades within a day, so mix what the job needs, keep surfaces visibly wet for 10 minutes, and never pair bleach with acids or ammonia.
How to use
- Pick imperial or metric.
- Pick the 100, 1000, or 5000 ppm target.
- Type the bottle percent from its label.
- Type the water amount.
- Read the bleach dose first.
- Mix, keep wet 10 minutes, air dry.
Formula
- target
- Target strength: 100, 1000, or 5000 ppm.
- stock
- Bottle strength, usually 5 to 9 percent.
- water
- Water to treat, in gal or L.
CDC Appendix E gives the same parts rule: (percent in bleach / percent wanted) minus 1 equals water parts per part bleach, with a 0.5% from 3.5% worked example at 6 parts. CDC household guidance keeps stock between 5% and 9% sodium hypochlorite. Ready.gov emergency chlorination uses 1/8 tsp per gallon of 5.25 to 6.0% bleach with a 30 minute stand.
Worked example
Example: 1,000 ppm gallon from 6% bleach
Imperial defaults: 1,000 ppm, 6% bleach, 1 gal water.
- Target 1,000 ppm from 6% stock in 1 gal.
- Bleach: 0.001 x 3785.41 / 0.06 = 63.09 mL.
- Spoons: 63.09 / 4.929 = 12.8 tsp, or 2.1 fl oz.
- Ratio: (6 / 0.1) minus 1 = 59 parts water per part bleach.
- Check: 1 to 59 of 6% gives 0.1%, which is 1,000 ppm.
- Tool shows 12.8 tsp (2.1 fl oz), 1 to 59, 1,000 ppm from 6% stock.
Reference table
| Job | Mix | Dose |
|---|---|---|
| 1 gal at 1,000 ppm, 6% | 1 to 59 | 12.8 tsp (2.1 fl oz) |
| 3.79 L at 1,000 ppm, 6% | 1 to 59 | 63.2 mL |
| 2 gal at 100 ppm, 5.25% | 1 to 524 | 2.9 tsp (0.5 fl oz) |
| 1 L at 5,000 ppm, 6% | 1 to 11 | 83.3 mL |
Limits
- Label percent rules; misread stock, misdosed batch.
- Splashless and scented products are excluded, not computed.
- Porous and metal surfaces have their own guidance.
- Organic soil load can demand cleaning before disinfecting.
Common mistakes
- Eyeballing capfuls instead of measuring.
- Using splashless or scented bleach.
- Storing the mix for next week.
- Mixing bleach with vinegar or ammonia.
- Skipping the 10 minute wet time.
Try it yourself
Quick checks. Answers sit tucked under each question.
100 ppm in 2 gal from 5.25%?
2.9 tsp (0.5 fl oz), 1 to 524, 100 ppm from 5.25% stock.
5,000 ppm in 1 L from 6%?
83.3 mL, 1 to 11, 5,000 ppm from 6% stock.
100 ppm in 1 gal from 6%?
1 gal at 100 ppm from 6% needs 1.3 tsp: small jobs need small measures.
Questions
How do ppm and percent convert?
Percent x 10,000. So 0.1% is 1,000 ppm and 0.5% is 5,000 ppm.
Which target for which job?
100 ppm for sanitizing rinsed food surfaces, 1,000 ppm for spill and surface disinfection, 0.5% for heavy soil jobs.
How long must it stay wet?
10 minutes of visibly wet contact for disinfection, then air dry. Immersion jobs run 30 minutes.
Any bleach works?
No. Scented, splashless, and color safe products lack the needed hypochlorite or add cleaners.
How long does the mix keep?
Yes. Make a fresh batch daily; light and heat break the mix down.
Mix with vinegar or ammonia?
Never. Bleach plus acids or ammonia releases toxic gases.
Sources
- CDC: chlorine disinfectant solution preparation (Appendix E)
- Ready.gov: water treatment (chlorination doses)