Free interactive tool
Estimate caffeine remaining at bedtime
The effect of an afternoon drink depends on dose, timing, bedtime and clearance. Use your own schedule rather than relying on a single cutoff rule.
- Bedtime-specific estimate
- Per-drink contribution
- Fast and slow metabolism comparison
What the estimate can tell you
CaffCalc applies exponential half-life decay to each dose, combines the results and shows the estimated amount over time. It is useful for comparing timing choices, not for diagnosing sleep problems or measuring caffeine in your body.