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Calculate hand washing effectiveness from duration and technique — see germ reduction and recommended time.
Calculate hand washing effectiveness from duration and technique — see germ reduction and recommended time.
Enter values above and click Calculate — results will appear here with the formula explained.
Proper 20s scrub with soap removes ~90% of germs. Quick rinse removes ~20%, 10s ~50%. 20 seconds is CDC recommendation.
This is estimate; germ type and soap matter. For YMYL infection control, wash 20s before eating and after restroom.
To use the Hand Washing Calculator, enter washing seconds, technique above for an instant result with full breakdown and formula (Reduction: proper 20s ~90%, 10s ~50%, quick rinse ~20%; Recommended 20s). Adjust values live to compare scenarios, then check the worked example and FAQs below for practical tips and costly mistakes to avoid.
Calculate hand washing effectiveness from duration and technique — see germ reduction and recommended time. Formula: Reduction: proper 20s ~90%, 10s ~50%, quick rinse ~20%. Example: With 20s proper: ~90% reduction, recommended.
Proper 20s scrub with soap removes ~90% of germs. Quick rinse removes ~20%, 10s ~50%. 20 seconds is CDC recommendation.
This is estimate; germ type and soap matter. For YMYL infection control, wash 20s before eating and after restroom.
To use the Hand Washing Calculator, enter washing seconds, technique above for an instant result with full breakdown and formula (Reduction: proper 20s ~90%, 10s ~50%, quick rinse ~20%; Recommended 20s). Adjust values live to compare scenarios, then check the worked example and FAQs below for practical tips and costly mistakes to avoid.
With 20s proper: ~90% reduction, recommended. With 5s quick: ~20%, not enough.
Formulas are standard public references (see our methodology). External standards are cited in the text where they apply.
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