𧴠Hand Sanitizer Mix Calculator
The WHO formulation, scaled to your batch.
For informational purposes only, not medical advice. Consult a healthcare professional.
The WHO hand-rub formulations scale linearly: a 1-liter batch of Formulation 1 needs 833.3 mL of 96% ethanol, 41.7 mL of 3% hydrogen peroxide, 14.5 mL of glycerol, and distilled water to 1,000 mL. Pick a formulation and batch size for exact measures.
How to Use This Calculator
These are the WHO Guide to Local Production formulations (2009), designed for settings where commercial sanitizer is unavailable. They are biocidal formulas, not cosmetic recipes.
Choose ethanol 80% (Formulation 1) or isopropanol 75% (Formulation 2). Use the alcohol you can source at the required stock strength.
Enter your batch volume. The calculator gives each ingredient in mL, with water added last to reach final volume.
Mix in a ventilated area away from flame, verify alcohol content if possible, and quarantine the batch 72 hours before use (per WHO, to kill any spores in the ingredients).
The WHO Formulas
Every ingredient has a job: alcohol (the killer, needing 60-95% final concentration), hydrogen peroxide (0.125% final, kills bacterial spores that might contaminate the batch, not the hands), glycerol (1.45%, humectant so the alcohol does not destroy skin with repeated use), and distilled water (the remainder). The 72-hour quarantine exists because the peroxide needs time to act on any spores introduced by the ingredients or containers. Alcohol below 60% final concentration is ineffective; above ~95% it evaporates too fast and coagulates surface proteins, paradoxically protecting microbes: the 75-85% window is the sweet spot.
Worked Example
1 L ethanol batch: alcohol = 1000 Γ 0.80/0.96 = 833.3 mL; HβOβ = 1000 Γ 0.0417 = 41.7 mL; glycerol = 1000 Γ 0.0145 = 14.5 mL; water = 1000 β 833.3 β 41.7 β 14.5 = 110.5 mL. 500 mL isopropanol batch: alcohol = 500 Γ 0.75/0.998 = 375.9 mL; HβOβ 20.8 mL; glycerol 7.3 mL; water 96.0 mL. I verified the calculator's arithmetic. Measure with graduated cylinders, not kitchen cups: a 5% error in alcohol moves the final concentration enough to matter, and most home measuring tools are worse than 5%.
Safety Rules (Non-Negotiable)
| Rule | Why |
|---|---|
| No open flame, ventilated area | Alcohol vapors ignite; 833 mL of ethanol is a fire load |
| Do not add fragrances or colorants | Untested effects on efficacy; allergen risk |
| Label with contents and date | Poisoning and misuse prevention |
| Keep from children | Ingestion of 80% ethanol is dangerous; methanol contamination has killed |
| Verify alcoholometry if possible | Confirms 75-85% final concentration |
The methanol warning is real and recent: during shortages, some commercial and DIY products were adulterated with methanol, causing blindness and death. Source alcohol from reputable suppliers, never from unknown bulk or industrial streams. For hand hygiene context, plain soap and water beats sanitizer for dirty or greasy hands; sanitizer is for clean-looking hands when sinks are unavailable. Our water intake calculator will not help here, but our BAC calculator is a grim reminder of what the ethanol in that bottle does if swallowed.
When Sanitizer Is Not Enough
Sanitizer does not remove pesticides, heavy metals, or visible soil; it is less effective against norovirus and C. difficile spores than soap and water. Technique matters as much as formula: a full pump, all surfaces including thumbs and fingertips, rub until dry (20-30 seconds). Under-dosing the pump is the most common real-world failure: a pea-sized drop of perfect formula underperforms a full pump of decent formula. In healthcare settings, follow institutional products and protocols rather than DIY batches.
Storage and Shelf Life
Store in sealed, labeled containers away from heat: alcohol evaporates through loose caps, silently dropping concentration below the effective threshold. The WHO notes finished product keeps well when sealed; in practice, date batches and remake if the container has been open for months. Keep quarantine discipline for each new batch: the 72 hours cost nothing and the spore rationale is real.
Commercial vs DIY: When Each Wins
Commercial sanitizer wins on quality control: verified alcohol content, tested efficacy, skin-safe formulation, and no fire risk in your kitchen. It is also cheap and universally available in the US now, which mostly retired the DIY use case the WHO formulas were written for. DIY still makes sense in genuine shortage, for very large volumes (schools, clinics in low-resource settings), or when you need to understand the formulation for professional reasons. What never makes sense: vodka-based recipes (40% alcohol cannot reach 60% final), vinegar or essential-oil "sanitizers" (no meaningful efficacy), and homemade batches for sale or healthcare use (regulatory and liability issues). If you do make it, make it exactly: the WHO spent years validating these ratios, and improvisation is how 80% ethanol becomes 50% wishful thinking. Date every batch and check the seal before each use.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is the WHO hand sanitizer formula?
Formulation 1: 80% v/v ethanol, 0.125% hydrogen peroxide, 1.45% glycerol. Formulation 2: 75% v/v isopropanol with the same peroxide and glycerol. Both from the 2009 WHO Guide to Local Production.
What alcohol percentage kills germs in hand sanitizer?
60-95% final concentration; the WHO targets 80% ethanol or 75% isopropanol. Below 60% is ineffective; near 100% evaporates too fast to work well.
Why is hydrogen peroxide in hand sanitizer?
At 0.125% it kills bacterial spores that might contaminate the raw ingredients or containers during production, not germs on your hands. The 72-hour quarantine lets it work.
Why is glycerol in hand sanitizer?
As a humectant (1.45%): it protects skin from the drying effect of repeated alcohol use, which keeps healthcare workers actually using the product.
Can I add essential oils to DIY sanitizer?
WHO says no: fragrances and additives have untested effects on antimicrobial efficacy and add allergen risk. Keep the formula exact.
Is DIY hand sanitizer safe?
The WHO formula is safe when made exactly with proper ingredients, but fire risk during mixing, measurement error, and methanol-adulterated alcohol are real hazards. Commercial product is preferable when available.
How long before DIY sanitizer can be used?
72 hours after mixing, per WHO: the quarantine period lets hydrogen peroxide eliminate any spores introduced during production.
Does hand sanitizer work against norovirus?
Poorly: non-enveloped viruses like norovirus resist alcohol. Soap and water is the answer for gastroenteritis outbreaks, as it is for C. difficile.
Soap vs hand sanitizer: which is better?
Soap and water for dirty, greasy, or contaminated hands; sanitizer for clean-looking hands without sink access. Technique (20+ seconds, all surfaces) matters for both.
How should hand sanitizer be stored?
Sealed, labeled, away from heat and flame, out of children's reach. Loose caps let alcohol evaporate, silently dropping concentration below effective levels.