Energy Drink Caffeine Half-Life Calculator
Model how caffeine from your coffee, tea or energy drink decays over the next 12 hours and see how much is likely left when you go to bed.
Processed entirely in your browser — nothing you enter here is ever uploaded.
Result
About this tool
This page opens the caffeine half-life calculator preloaded with a typical energy drink dose — about 160 mg, roughly what a standard 16 oz can delivers — and computes the decay curve immediately.
That is nearly double a cup of drip coffee, so the tail matters more: at the average 5-hour half-life, a can finished at 4 pm still leaves around 40 mg in your system by midnight, more if you drank it later or metabolize caffeine slowly. The bedtime callout below turns that into a single, personal milligram figure.
Set the time you drank it and your usual bedtime above for your own estimate, or switch to coffee, espresso, tea or a custom milligram amount using the drink selector.
Example. A 95 mg coffee read 5 hours later shows 47.5 mg remaining.
Limit. The half-life is fixed at 5 hours and the plotted curve stops at hour 12.