Hand Sanitizer Calculator - Coronavirus

Scale the WHO alcohol handrub formula to any batch size: enter the alcohol you have, a target concentration, and a volume to get the exact amounts of alcohol, glycerol, hydrogen peroxide, and water to mix.

Quick Facts

WHO formulations
~80% v/v ethanol or ~75% v/v isopropyl alcohol
WHO's published local-production handrub recipes land at these final strengths.
Effective minimum
60% ethanol / 70% isopropyl (CDC/WHO)
Below this, alcohol-based sanitizers are considered less effective against most pathogens.
Additives
Glycerol 1.45% v/v, hydrogen peroxide 4.17% v/v of stock
Glycerol protects skin; dilute peroxide helps kill bacterial spores that may contaminate bulk alcohol.

Your Results

Calculated
Alcohol to add
-
mL of your source alcohol
Water to add
-
mL to complete the batch
Glycerol to add
-
mL of 98% glycerol (skin protectant)
Hydrogen peroxide to add
-
mL of 3% stock solution

Ready

Enter your alcohol strength, target concentration, and batch volume, then calculate the mix.

About the Hand Sanitizer Calculator - Coronavirus

This calculator scales the World Health Organization's published "Guide to Local Production: WHO-recommended Handrub Formulations" to any batch size. WHO describes two formulations - one built on 96% ethanol, the other on 99.8% isopropyl alcohol - each combined with glycerol and dilute hydrogen peroxide and topped up with water. The calculator applies the same ratios (and a simple dilution equation for the alcohol itself) so you can enter whatever alcohol strength you actually have on hand and whatever batch size you need.

The formula behind the numbers

  • Alcohol volume uses the standard dilution relationship: alcohol needed = (target % x batch volume) / (source alcohol %). This is the same math as diluting any concentrated liquid to a weaker working strength.
  • Glycerol is added at 1.45% of the final batch volume - WHO's ratio for a skin-conditioning humectant that offsets the drying effect of alcohol.
  • Hydrogen peroxide (from 3% stock) is added at 4.17% of the final batch volume - WHO includes it to help inactivate bacterial spores that can contaminate bulk alcohol stock, not as an active ingredient in the finished sanitizer.
  • Water makes up whatever volume remains: batch volume minus alcohol, glycerol, and peroxide.

Reading your result

The calculator reports the exact volumes to combine and the alcohol percentage the mix achieves. CDC and WHO guidance calls for at least 60% alcohol by volume for ethanol-based products, or 70% for isopropyl-based products, to be considered effective against most bacteria and enveloped viruses (including coronaviruses). WHO's own formulations land higher, at roughly 80% ethanol or 75% isopropyl, to leave a margin above that floor.

When to consult a professional

This tool performs the mixing arithmetic only - it does not evaluate product safety, shelf stability, container compatibility, or skin sensitivity. If you plan to distribute a batch to others, are unsure about ingredient purity or sourcing, or have skin sensitivities, check with a pharmacist or your local health authority before use.

Frequently Asked Questions

What formula does this hand sanitizer calculator use?
It scales the WHO local-production handrub formulations: a target concentration of alcohol (diluted from whatever strength you have using alcohol needed = target% x volume / source%), plus glycerol at 1.45% of the batch and hydrogen peroxide at 4.17% of the batch, with water filling the remainder. WHO's own recipes reach about 80% v/v for ethanol or 75% v/v for isopropyl alcohol.
How much alcohol does hand sanitizer need to be effective?
CDC and WHO guidance recommends at least 60% alcohol by volume for ethanol-based sanitizer, or 70% for isopropyl-based sanitizer, for effectiveness against most bacteria and enveloped viruses such as coronaviruses. Diluting below those levels reduces effectiveness, which is why the calculator flags a target concentration that falls under the recommended minimum for the alcohol type selected.
Why does the WHO recipe include glycerol and hydrogen peroxide?
Glycerol (1.45% of the batch) is a humectant that helps offset the skin-drying effect of high alcohol concentrations. Hydrogen peroxide (4.17% of the batch, from a 3% stock solution) is included to help inactivate any bacterial spores that might be present in bulk alcohol during production - it is not intended as an active disinfecting ingredient in the finished product.

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