Caffeine Calculator
Calculate caffeine intake and when it'll wear off.
Total Caffeine Intake
95
mg
Caffeine Remaining Over Time
After 1 hour:83 mg
After 2 hours:72 mg
After 3 hours:63 mg
After 4 hours:55 mg
After 5 hours:48 mg
After 6 hours:41 mg
After 7 hours:36 mg
After 8 hours:31 mg
Based on ~5 hour caffeine half-life
How to Do It Manually
Caffeine has a half-life of 5–6 hours. After that time, half the caffeine remains in your system. Use this to plan your last caffeine intake before bed.
Remaining Caffeine = Initial Dose × (0.5)^(hours elapsed ÷ 5.5)
- Determine how much caffeine you consumed (e.g., 200 mg in coffee).
- Note the time consumed.
- Calculate hours until your target time (e.g., bedtime).
- Apply the half-life formula to find remaining caffeine.
Frequently Asked Questions
How much caffeine is in common drinks?
Coffee: 100–200 mg, Tea: 25–50 mg, Soda: 40–60 mg, Energy drink: 80–300 mg.
When should I stop drinking caffeine?
Stop at least 8–10 hours before bed to minimize sleep disruption.