Caffeine Half-Life Calculator
See how much caffeine is still in your system and when it will clear — so it doesn't wreck your sleep.
How this is calculated
Caffeine decays exponentially with a ~5-hour half-life (longer in pregnancy or on the contraceptive pill, shorter in smokers): remaining = dose × 0.5^(hours / half-life).
Sources
This calculator is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. The result is based on standard clinical formulas applied to the values you entered — your individual situation may need adjustments your doctor can make. Never disregard professional medical advice or delay seeking it because of something you read or calculated on healthcalculus.