Half-life is a simple way to estimate how quickly caffeine declines. It’s not perfect — but it’s useful for planning cutoff time.
If your half-life is 5–6 hours, about half of the caffeine remains after that time. Longer half-life means caffeine lingers later into the evening.
Genetics, medications, pregnancy, and other factors can change how quickly you clear caffeine. That’s why sensitivity tiers exist.
If you’re unsure, start conservative (High sensitivity), then adjust after observing your sleep over a week.
No. This guide is educational. If you have health concerns or take medications, talk to a clinician.
Use the tools first, then come back here if you want the “why” behind the numbers.