Online Tool Store
Caffeine Half-Life Calculator
Estimate caffeine remaining over time with a configurable half-life. Use the timeline as a planning guide, not a medical measurement.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Estimated amount remaining
Example shown — this is educational, not medical advice. Individual metabolism varies.
How it works
- Enter the caffeine amount from your drink and the hours since you had it.
- Select a half-life estimate that best represents your situation.
- Review the estimated remaining amount as a planning guide.
The formula
remaining caffeine = dose × 0.5^(hours ÷ half-life)
FAQ
What is caffeine half-life?
It is the approximate time it takes for the amount of caffeine in the body to fall by half.
Why does the estimate vary?
Pregnancy, medications, smoking, health conditions, age, and genetics can all change how quickly caffeine is processed.
Can this tell me when I will sleep?
No. It estimates caffeine amount only. Sensitivity and sleep response differ widely between people.
How we compare
| Feature | Online Tool Store | Sleep Cycle | Caffeine Informer |
|---|---|---|---|
| Remaining-caffeine estimate | Yes | Limited | Yes |
| Sleep tracking | No | Yes | No |
| No account required | Yes | Varies | Yes |
Use this quick local estimate to plan caffeine timing, while treating it as a guide rather than a personal medical measurement.