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//// Health · Nutrition
Caffeine Half-Life Calculator
Enter when you drank it and how much — see your current mg level, a 12-hour decay curve, and when you'll drop below the sleep-safe threshold.
Where this fits
This tool sits in the health domain and connects best with the next tools in that decision lane.
Healthy BMI18.5 – 24.9
Daily Calories2,000 – 2,500
Sleep Cycle90 min
Caffeine Dose
Quick Presets
Timing & Metabolism
Population range: 3–7 hrs. Slower in pregnancy, on some medications.
Right Now
74.5mg
78.4% of dose
Sleep-Safe In
3h 18m
<50mg threshold
At 10% Left
16h 54m
from now
Decay Over Next 12 Hours
| Hours from Now | mg Remaining | % of Dose |
|---|---|---|
| Now | 74.5 | 0.8% |
| +2h | 58.4 | 0.6% |
| +4hsleep ok | 45.8 | 0.5% |
| +6hsleep ok | 35.9 | 0.4% |
| +8hsleep ok | 28.2 | 0.3% |
| +10hsleep ok | 22.1 | 0.2% |
| +12hsleep ok | 17.3 | 0.2% |
25% remaining
9h 24m
10% remaining
16h 54m
5% remaining
22h 36m
Caffeine half-life varies significantly (3–7 hrs) based on genetics, liver enzymes, medications, and pregnancy. These estimates use the population average of 5.7 hours. Not medical advice.
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