Caffeine Calculator
Track caffeine levels in your body and estimate sleep impact over time. Free online caffeine half-life calculator.
Embed this toolCaffeine Remaining
of 200mg consumed
High chance of sleep disruption.
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Common Drinks Caffeine Reference
Use this quick reference to estimate your total caffeine intake. Amounts are approximate and can vary by brand, brewing method, and serving size.
Caffeine Half-Life and Sleep
Caffeine is the most widely consumed psychoactive substance in the world. Once ingested, it is rapidly absorbed into the bloodstream and reaches peak levels within 30 to 60 minutes. Its effects can last for several hours because the liver metabolizes caffeine at a relatively slow and steady rate. Understanding your personal caffeine clearance is important because even moderate afternoon consumption can reduce deep sleep and increase nighttime awakenings. Factors like age, pregnancy, liver health, and concurrent medications can significantly slow caffeine metabolism, making tools like this calculator especially useful for planning cut-off times.