See how much caffeine is still active in your system right now, and roughly when it should drop low enough to stop interfering with sleep.
Caffeine breaks down in the body following exponential decay: remaining amount = dose × 0.5^(hours elapsed ÷ half-life). This calculator applies that formula directly using the amount, time elapsed, and half-life you enter.
To estimate when it will fall to your chosen "low-impact" threshold, it works the formula in reverse, solving for the number of hours needed for the remaining amount to reach that target level — useful for roughly gauging how late in the day caffeine might still be affecting your sleep.
No — it's a general educational estimate based on average pharmacokinetics, not a personalized medical assessment. Individual caffeine metabolism varies significantly.
Genetics (particularly the CYP1A2 enzyme that metabolizes caffeine), liver function, pregnancy, smoking status, and certain medications can all significantly speed up or slow down caffeine breakdown.
Roughly: a cup of coffee has about 80-100mg, black tea about 40-50mg, and a can of cola about 30-40mg, though brands and brewing methods vary these figures considerably.