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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.
Caffeine Calculator is a high-performance utility designed to help users streamline their workflow. Built with modern web technologies, it ensures fast processing times and high-quality outputs directly in your browser.
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.