Caffeine Half Life Calculator
Use this free caffeine half life calculator to see how much caffeine is left in your body after a given time.
Health information notice: Results are estimates based on general formulas and may not reflect individual circumstances. This tool is not a diagnosis or substitute for personalized advice from a qualified healthcare professional.
How the caffeine half life calculator works
Remaining = dose × 0.5^(hours ÷ half-life). The average half-life is about 5 hours but varies from 2 to 10.
Frequently asked questions
How long does caffeine stay in your system?
Half is gone in about 5 hours for most adults; the rest takes much longer. Pregnancy, medicines and genetics change this.
Results are estimates for general information only. They are not a substitute for professional advice where applicable. Found a mistake? Report an error.