You should scrub your hands with soap for at least 20 seconds. That’s the scrubbing time alone, not counting the time spent wetting, rinsing, or drying. Scientific studies confirm that 20 seconds of lathering removes significantly more harmful germs and chemicals than shorter washes.
Why 20 Seconds Matters
Soap doesn’t kill most germs on contact. Instead, it works by loosening them so they slide off your skin during rinsing. The surfactants in soap lift dirt, grease, and microbes from the surface of your skin and out of tiny folds and creases. Friction from rubbing your hands together does the rest, physically dislodging pathogens that cling to skin. Both actions need time to work, and 20 seconds is the threshold where the combination becomes effective enough to meaningfully reduce contamination.
If you wash for a shorter time, you simply leave more germs behind. People also tend to scrub more thoroughly when they use soap rather than water alone, which is part of why soap outperforms a plain water rinse even at the same duration.
The Five Steps
The CDC breaks handwashing into five steps:
- Wet your hands under clean, running water (warm or cold), turn off the tap, and apply soap.
- Lather by rubbing your hands together. Work the soap over the backs of your hands, between your fingers, and under your nails.
- Scrub for at least 20 seconds. A common timer: hum “Happy Birthday” from start to finish twice.
- Rinse thoroughly under clean, running water.
- Dry with a clean towel or air dryer.
The 20-second count applies only to step three. The full process from wet hands to dry hands takes roughly 40 to 60 seconds in practice.
Spots Most People Miss
Palms get plenty of attention. Fingertips, thumbs, the spaces between fingers, and the backs of your hands do not. These are the areas where germs survive a lazy wash. The NHS recommends a specific sequence to cover them all: rub the back of each hand with the opposite palm while interlacing your fingers, then grip the fingers of one hand against the opposite palm to scrub the fingertips, and individually rotate each thumb inside the other hand’s grip. Under the nails is another common blind spot, especially if your nails are long.
Water Temperature Doesn’t Matter Much
Hot water feels more thorough, but it isn’t. A study testing water temperatures ranging from 15°C (60°F) to 38°C (100°F) found no significant difference in bacteria removal. What did matter was lather time and friction. Use whatever temperature is comfortable. The only real downside of hot water is that frequent exposure can dry out and irritate your skin, which over time can actually create tiny cracks where bacteria thrive.
When Soap Beats Hand Sanitizer
Alcohol-based hand sanitizer is a solid backup when you can’t get to a sink, but it has clear limits. It does not work well against norovirus (the most common cause of stomach bugs), Cryptosporidium (a waterborne parasite), or C. difficile (a bacteria that causes severe diarrhea). These pathogens require soap and running water to physically wash them away. Sanitizer also struggles when your hands are visibly dirty or greasy, because the grime shields germs from the alcohol.
When you do use sanitizer, apply enough to cover all surfaces of your hands and rub until completely dry, which takes about 20 seconds.
Healthcare Settings Use Longer Scrub Times
In hospitals and clinics, the baseline handwashing recommendation for staff is at least 15 to 20 seconds of scrubbing with soap, similar to the public guideline. Surgical hand preparation is a different category entirely. Surgeons scrub their hands and forearms for two to six minutes before operating, depending on the antiseptic product used. Older guidelines called for 10-minute scrubs, but those have been dropped as unnecessary.
For everyday life, 20 seconds of thorough scrubbing with regular soap is enough to protect you and the people around you.