Bleach Dilution Calculator

Measure the bleach. Measure the water. Understand the dilution.

Prepare your dilution

Label basisStock strength · C₁% w/v

Illustrative strengths, not product recommendations. Confirm the concentration basis on your label.

Target chlorine · C₂

Final solution volume · V₂

CHLORINE UNIT CHECK1,000 ppm = 0.100% w/vHere ppm means mg/L of available chlorine.

Label basis, density & measurement notes

Available-chlorine % w/v is not automatically identical to sodium-hypochlorite % w/w. NaOCl is converted to available-chlorine equivalent using 70.90/74.44 ≈ 0.952445. Use the product's stated chemical basis.

Volumetric dilution assumes additive volumes and no active-chlorine loss. Old bleach can be weaker than its original label strength.

Label wet contact time (optional)min

Copy from the applicable product label. This tool does not infer contact time or product efficacy.

Final volume means bleach + water.
Do not add the calculated bleach to a full 1 L of water; that would exceed the intended final volume.

BLEACH TO MEASURE · V₁19.05 mL

Calculated recipe · follow product-label directions.

Water to add980.95 mL

Final volume1.00 L

Target chlorine1,000 ppm

Your mixing plan

Water first · then bleach

Illustrative water jug, small bleach measure and final mixing pail

1980.95 mLRoom-temperature water

219.05 mLAdd measured bleach

31.00 LFinal diluted solution

Final-volume breakdown1.905% stock · 98.095% water

Stock bleachWater

Glassware, liquid levels and color are illustrative. Use the calculated quantities, not the picture, for measurement.

BLEACH : WATER1 : 51.552.5× total dilution · not a 1:51.5 stock-to-total ratio

◷Contact time comes from the product label.Keep the surface visibly wet for the specified time. Concentration alone does not establish effectiveness.

Check label before use

Choose a reference, then verify the label

Examples · not universal protocols

Surface / setting	Illustrative target	What to verify
Food-contact sanitizing	100–200 ppm	Only an approved product/use. Follow label concentration, contact time and rinse directions.
Environmental surfaces	1,000 ppm · 0.1%	WHO COVID-19 guidance example; check the organism, setting, surface and current local protocol.
Large blood / body-fluid spill	5,000 ppm · 0.5%	WHO spill-guidance example. Requires the appropriate trained-staff procedure and PPE.

These examples do not establish high-level disinfection, medical-device sterilization or suitability for every pathogen. Do not apply surface disinfectants to skin, food or animals.

Formula & worked example

C₁V₁ = C₂V₂ → V₁ = C₂V₂ / C₁

Stock = 5.25% available chlorine = 52,500 mg/L
Target = 1,000 mg/L · Final volume = 1,000 mL
Bleach = 1,000 × 1,000 ÷ 52,500 = 19.05 mL
Water ≈ 1,000 − 19.05 = 980.95 mL

Uses a common available-chlorine basis, additive volumes and the supplied stock strength. It does not test actual chlorine content.

What does “1:10” mean?

Bleach : water1 + 10 = 11 parts totalFinal strength = stock ÷ 11

Bleach : final solution1 + 9 = 10 parts totalFinal strength = stock ÷ 10

Select the ratio convention explicitly. Never guess which meaning a recipe uses.

A practical preparation checklist

Read & pre-clean

Use a product approved for the task. Remove visible soil before disinfection; follow rinsing directions.

Measure & dilute

Use room-temperature water and label-required PPE. Add measured bleach to water without splashing.

Label & use correctly

Record strength and preparation date. Follow the label’s contact time, storage and solution-life instructions.

Frequently asked questions

Can I mix bleach with vinegar, ammonia or another cleaner?

No. Mixing bleach with acids, ammonia or other cleaning products can release dangerous gases. Use it only as directed on the product label.

Is 1% always 10,000 ppm?

1% w/v equals 10,000 mg/L. This tool uses ppm as mg/L available chlorine. Strict mass-fraction ppm depends on the solution density; sodium-hypochlorite percentage and available-chlorine percentage are not interchangeable without checking their bases.

Can I use old, scented or splashless bleach?

Check the product label. CDC household guidance uses regular unscented bleach with a stated sodium-hypochlorite strength, and warns that some laundry/splashless products are inappropriate for disinfection. Degradation can make the original strength unreliable.

Does a higher concentration work better for every task?

No. The required concentration, wet contact time, surface compatibility and rinsing depend on the product and task. A stronger mixture can increase exposure and material-damage risks.

Does this tool determine a contact time or certify disinfection?

No. It calculates a dilution from supplied inputs. The product label and applicable protocol determine use instructions and wet contact time.

Live calculations require JavaScript. The static example uses 5.25% w/v available chlorine, target 1,000 mg/L and final volume 1 L: approximately 19.05 mL stock plus 980.95 mL water. Follow the product label; this is not an efficacy certification. Formula, reference information and FAQs remain available.

Sources & Reference Guides

CDCUsing bleach correctlyLabel directions, ventilation and handling.WHOEnvironmental surfacesContext-specific chlorine guidance.EPAProduct-label requirementsApproved uses and contact-time directions.

Handling reference: CCOHS · WHO technical guidance (2020)
Independent reference material · No institutional endorsement or product approval implied.

NaOCl molar mass · Cl₂ equivalent molar mass

↗ Chemistry