Health Calculator
Caffeine Calculator
Calculate how much caffeine remains in your body and estimate when it will wear off.
Results
Estimates based on exponential caffeine decay.
Remaining caffeine
90.9mg
75.8% remaining · 2.0h since intake
Estimated clearance time
Jul 25, 2026, 04:38 PM
Approximate time when levels fall near 1mg.
Sleep impact
ModerateHigh >100mg · Moderate 50–100mg · Low <50mg
Caffeine FAQ
How long does caffeine stay in your body?+
Caffeine usually has a half-life of around 5 hours, but it varies between individuals based on age, genetics, liver function, and other factors.
How accurate is this caffeine calculator?+
It uses a standard exponential half-life model to estimate remaining caffeine. Real-world results can differ, so treat the output as a helpful estimate—not medical advice.
Can caffeine affect sleep?+
Yes. Higher remaining caffeine later in the day can make it harder to fall asleep. This calculator includes a simple sleep impact guide based on remaining milligrams.