Caffeine Decay in the Body Over 8 Hours
Caffeine has roughly a 5–6 hour half-life; at a 12% hourly decay rate, 200 mg drops to about 67 mg after 8 hours.
How to use this tool
- Enter initial value, decay rate per period and number of periods in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your remaining value and the full breakdown beneath it.
Model how caffeine is metabolized in the body by applying an approximate hourly decay rate.
Frequently asked questions
- What is the difference between decay rate and half-life?
- The decay rate r is the fraction lost each period; the half-life is the number of periods until only half remains. They are linked by t½ = log(0.5)/log(1−r).
- Does this assume continuous or discrete decay?
- This calculator uses discrete (period-by-period) decay. For continuous decay use A = A₀·e^(−λt) with the half-life calculator.