Caffeine Half-Life Calculator

See how caffeine decays in your body over time — plan your last coffee for better sleep.

Caffeine dose (mg)

Half-life (hours)

Enter your dose above.

Informational only, not medical advice.

How to use

Enter your caffeine dose and time to see the decay timeline.

What is caffeine's half-life?

About 5-6 hours for most adults — a 200 mg coffee at noon leaves ~100 mg at 5-6 PM. It varies by person and medication.

When should I stop drinking coffee?

Most sleep experts suggest no caffeine 8-10 hours before bed. General guidance, not medical advice.

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