How we worked it out
Updated as you change the numbers.
- Remaining = dose × (1/2)^(hours ÷ half-life).
Method and assumptions
The FDA cites 400 mg a day as an amount not generally associated with negative effects for most healthy adults.
Questions
How much of 200 mg of caffeine is left after 6 hours?
About 87 mg with a 5-hour half-life.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.