Sleep cycles
A wake time or bedtime from 90-minute cycles plus the minutes you need to fall asleep.
Open a calculatorCaffeine left
Remaining = dose × ½^(hours / half-life). The usual adult half-life is about five hours. Pregnancy, the pill and smoking move it. Not medical advice.
mg
Still in you
100 mg
Share left
50%
Still in you: 100 mg
A 200 mg coffee and a five-hour half-life leave about 100 mg at five hours.
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An educational estimate. Not medical, tax or credit advice.