Loading Legacy
Track your daily caffeine intake, see real-time levels using the 5.5-hour half-life formula, and find your last safe coffee time.
Log a Drink
Current Caffeine Level
0 mg
Minimal Effect
FDA safe limit: 400 mg/day
Caffeine Calculator tracks your daily caffeine intake across 10+ common drinks, models real-time caffeine levels using the 5.5-hour half-life formula (remaining = initial × 0.5^(hours/5.5)), and calculates your last safe coffee time for a good night's sleep.
Log your drinks, see how much caffeine remains in your system right now, and find out when to stop drinking coffee for a good night's sleep.
Log each drink with its consumption time.
See your current caffeine level update in real time.
Use the Sleep Impact tab to find your caffeine cutoff.
Caffeine elimination uses first-order kinetics: remaining_mg = initial_mg × 0.5^(hours / 5.5). Half-life of 5.5 hours is the FDA/scientific consensus estimate. Actual half-life varies 1.5–9.5h based on genetics, pregnancy, medications.
Approximately 5.5 hours — meaning half the caffeine is eliminated from your body every 5.5 hours.
The FDA recommends no more than 400mg per day for healthy adults.