Free Health Tool
Coffee Caffeine Calculator
Add your drinks and the times you consumed them to generate a real-time caffeine half-life chart. See exactly when caffeine clears your system and whether your intake will affect your sleep.
1
Planned bedtime
:
Caffeine sensitivity
Peak caffeine: 95 mg. Drops below sleep-safe level at 12:45 PM.95 mg peak
95Total mg today
95Peak mg
54Est. now (mg)
13At bedtime (mg)
12:45 PMSleep-safe at
Caffeine Half-Life Chart
5h half-life (normal)Sleep safe: 50 mgDaily limit: 400 mg
Caffeine levelSleep-safe thresholdDaily limit
Drink Breakdown
| Drink | Time | Caffeine | Half at | Contribution |
|---|---|---|---|---|
| Drip coffee (8 oz) | 8:00 AM | 95 mg | 1:00 PM |
At your planned bedtime you will have approximately 13 mg of active caffeine. Effect level: Negligible. Effectively cleared. Minimal impact on sleep or alertness.Negligible
How caffeine metabolism works
Caffeine has a half-life of approximately 5 hours meaning half of it is still active 5 hours after consumption
A coffee at 2 PM still leaves 25% of its caffeine active at midnight, which is enough to delay sleep onset
Half-life varies from 3 to 10 hours between individuals due to genetics, liver enzyme activity, and medications
Oral contraceptives and some antibiotics slow caffeine metabolism while smoking accelerates it
Caffeine blocks adenosine receptors in the brain, masking tiredness without actually reducing sleep pressure
The FDA recommends a maximum of 400 mg of caffeine per day for healthy adults
Pregnant individuals are advised to limit caffeine to under 200 mg per day
The sleep-safe threshold of 50 mg is a conservative estimate. Sensitive individuals may be affected at lower levels
Cold brew is often higher in caffeine per ounce than drip coffee due to its higher coffee-to-water ratio
All calculations happen in your browser in real time and no personal data is stored or transmitted anywhere
Caffeine values are approximate averages and vary by brand, brewing method, and serving size. This tool is for general educational use only and is not a substitute for advice from a qualified healthcare provider.
