Bleach Dilution Calculator 2026-27 — GlobalCalc

GlobalCalc

Inputs

Bleach strength

Available chlorine, from the label

Target concentration

ppm

Final volume

Age of the bleach

Results update as you type

Results

Bleach to add

47.62 mL

Water to add (L)—

Dilution factor—

Effective strength used—

Approximate capfuls (20 mL)—

Bleach per litre of water (mL)—

Typical use at this strength—

Reviewed September 2026. Chemistry is the same in every country: SI and laboratory units throughout.

All calculations run 100% in your browser. The calculator code does not submit your figures to GlobalCalc to obtain a result.

About bleach dilution

Method

How the bleach dilution calculator works

Household bleach is sodium hypochlorite, usually 4 to 8.25% available chlorine. To reach a target in ppm, the volume of bleach is target × final volume ÷ (concentration × 10,000).

The two figures that matter most are not in the arithmetic: bleach loses strength on the shelf — perhaps 20% a year — and it must never be mixed with acid or ammonia, which releases chlorine or chloramine gas.

Formula: bleach mL = ppm × litres / (% × 10,000) × 1,000

Data

Worked examples

Inputs	Bleach to add	Note
200 ppm in 10 L from 4.2% bleach	47.62 mL	47.6 mL — food-contact sanitising
1,000 ppm for disinfection	238.1 mL	238 mL
Year-old bleach	59.52 mL	25% more needed

FAQ

Frequently asked questions

How strong is household bleach?

Typically 4 to 8.25% available chlorine. Check the label — the figure varies by brand and country.

What concentration should I use?

200 ppm for food-contact sanitising, 500 to 1,000 ppm for surface disinfection. Follow the guidance of whichever authority applies to your setting.

Does bleach expire?

Yes. It loses roughly 20% of its strength in a year at room temperature, faster if warm or in sunlight. This calculator can allow for it.

What must I never mix with bleach?

Acid, which releases chlorine gas, and ammonia, which releases chloramine. Both have killed people in domestic settings.

Does diluted bleach keep?

Poorly. A working solution loses strength within about a day, so mix it fresh.

Sources

Where these figures come from

IUPAC — Standard atomic weights (2021 conventional values) — the molar-mass table
NIST — CODATA 2018 fundamental physical constants — Avogadro constant, gas constant, speed of light
NIST Chemistry WebBook — thermochemical data
Royal Society of Chemistry — the UK chemistry professional body

Last checked: September 2026. Atomic masses are the IUPAC conventional values; constants are CODATA 2018; equations are the standard textbook forms.