Caffeine Calculator
Caffeine Remaining
Formula
Remaining Caffeine = Initial mg × 0.5^(hours / 5). Half-life ≈ 5 hours. Time to target = 5 × log₂(current / target).
Frequently Asked Questions
What is the half-life of caffeine?
The average half-life of caffeine is approximately 5 hours, meaning half the caffeine is eliminated from your body every 5 hours. Individual half-lives can range from 3 to 7 hours.
How much caffeine is in common beverages?
An 8 oz cup of coffee has about 80–100 mg, espresso about 63 mg per shot, black tea about 47 mg, and a 12 oz cola about 34 mg of caffeine.
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