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Caffeine Half-life & Sleep Impact Calculator

Calculate caffeine levels in your body over time and check sleep impact. Calculator uses exponential decay with 5.5-hour half-life.

All Drinks

Advanced Settings

The time you usually go to sleep

Optional: weight in kg to calculate mg/kg

Results

Did you know?

BMR (Basal Metabolic Rate) is the minimum number of calories needed to maintain basic body functions.

Data Visualization

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How does this calculator work?

Calculate caffeine levels in your body over time and check sleep impact. Calculator uses exponential decay with 5.5-hour half-life.

Free online calculator. Accurate calculations. Easy to use.

Frequently Asked Questions

Our caffeine calculator on estim.at uses the exponential decay formula: Remaining_Caffeine = Initial_Dose ร— 0.5^(Hours_Elapsed / Half_Life). Default half-life is 5.5 hours, but you can adjust it based on metabolism speed (slow: 8h, normal: 5.5h, fast: 3h).
Caffeine stops significantly affecting sleep when its level drops below 25 mg. Our calculator shows the exact time when caffeine level drops below this threshold, helping you plan optimal bedtime.
Yes, our calculator allows you to add multiple caffeinated drinks consumed at different times. The calculator sums all doses and calculates total caffeine level in your body over time, accounting for exponential decay of each dose.
The sleep threshold is the caffeine level (25 mg) below which caffeine no longer significantly affects sleep quality. Our calculator shows when caffeine level drops below this threshold, helping you plan optimal bedtime.
Yes, our calculator allows you to enter body weight (optional), which enables calculation of caffeine level in mg/kg. This helps better understand caffeine impact on the body, as people with higher body mass can tolerate higher caffeine doses.