Hand Sanitizer Calculator
HealthCalculate the amounts of alcohol and aloe vera gel needed for a WHO-style DIY hand sanitizer recipe at any batch size and target alcohol concentration.
Alcohol Needed
353.5
Aloe Vera Gel Needed
146.5
What is a Hand Sanitizer Recipe?
The Hand Sanitizer Calculator computes the amount of alcohol and gel base needed to make a DIY hand sanitizer batch at a target final alcohol concentration, based on commonly published home recipe ratios. Enter your batch size, your starting alcohol concentration, and your target final concentration, and the calculator returns the exact mix.
How to use this Hand Sanitizer Recipe calculator
- Enter your desired batch size in millilitres.
- Enter the alcohol concentration of the alcohol you're starting with (e.g. 99% isopropyl alcohol).
- Enter your target final alcohol concentration (commonly 70%).
- Read the Alcohol Needed and Aloe Vera Gel Needed amounts instantly.
- Mix thoroughly and store in a clean, sealed, clearly labeled container away from heat.
Formula & Methodology
Alcohol Needed = (Batch Size × Target Concentration) ÷ Starting Alcohol Concentration Aloe Vera Gel Needed = Batch Size − Alcohol Needed Worked example — a 500 mL batch, starting with 99% isopropyl alcohol, targeting 70% final concentration: Alcohol Needed = (500 × 70%) ÷ 99% = 353.5 mL Aloe Vera Gel Needed = 500 − 353.5 = 146.5 mL
Frequently Asked Questions
The World Health Organization published a reference formula for making hand sanitizer using high-concentration alcohol combined with a small amount of glycerol and hydrogen peroxide. This calculator uses a simplified alcohol-and-aloe-vera-gel approach common in home DIY recipes, which follows the same core dilution principle.
Health authorities commonly reference a final alcohol concentration of at least 60-70% as effective against many common germs, which is why this calculator defaults to a 70% target concentration.
Undiluted high-concentration alcohol (like 99% isopropyl) evaporates too quickly and can be harsh on skin, so it's typically mixed with a gel base like aloe vera to slow evaporation, improve skin feel, and reach a target concentration that's both effective and practical to use.
The calculator uses the concentration dilution formula: it multiplies your target batch size by the target concentration, then divides by the concentration of the alcohol you're starting with, to find how much of that alcohol is needed.
Yes — the same dilution math applies to ethanol or isopropyl alcohol as long as you enter the correct starting concentration; both are commonly referenced in DIY hand sanitizer recipes at similar target final concentrations.
If your starting alcohol concentration is already at or below your target concentration, you won't be able to reach the target by diluting further with a non-alcohol gel — the calculator would suggest all or nearly all alcohol with no meaningful dilution, and a stronger starting alcohol would be needed instead.
A correctly mixed batch at an effective alcohol concentration follows similar principles to commercial products, but homemade batches lack the manufacturing quality controls, testing, and shelf-stability additives of commercial products, so store-bought sanitizer is generally the more reliable choice when available.
It should be stored in a clean, sealed, clearly labeled container away from heat and open flame, since it's flammable, and used within a reasonable timeframe as homemade batches don't have the same shelf-life testing as commercial products.
No — this is a general household recipe ratio calculator based on commonly published DIY formulas. It does not replace guidance from public health authorities or product safety information for hand hygiene.
This calculator computes a DIY recipe ratio, while the [Event Risk Calculator](/event-risk-calculator/) estimates the statistical chance of an infectious attendee at a gathering — both relate to general infection-prevention topics but serve very different purposes.
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