Caffeine Calculator
Track your daily caffeine intake across coffee, tea, energy drinks, and more. See total caffeine consumed, how much is still active in your system based on the 5.7-hour half-life, and when it will drop to a safe level for sleep.
Safe limit is generally 400mg/day for healthy adults (about 6mg/kg)
How to use
- Add each drink you've had today, when you had it, and how many.
- Enter your body weight for a more accurate safe-limit comparison.
- Click Calculate to see total caffeine, what's still active now, and what time your caffeine should clear.
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Caffeine has a half-life of about 5-6 hours in most adults. That afternoon coffee at 3 PM still has half its caffeine active at 8-9 PM, which explains why many people have trouble falling asleep even several hours after their last drink. A double espresso at 4 PM leaves roughly 64mg active by midnight.
This calculator tracks your total daily caffeine intake and estimates how much remains active in your bloodstream at any given time. FDA considers 400mg per day safe for most healthy adults. Heavy caffeine users often have above that without realising it - a large filter coffee at a cafe is often 250-300mg on its own, and energy drinks can pack 150-300mg per can.
Frequently Asked Questions
How much caffeine is too much?
FDA guidelines suggest 400mg/day as a safe upper limit for healthy adults. Pregnant women are advised to stay under 200mg. Individual sensitivity varies widely - some people feel anxious at 100mg; others handle 500mg without issues. Listen to your body alongside following guidelines.
What is the caffeine content of common drinks?
Espresso (30ml): 60-80mg. Drip coffee (240ml): 80-120mg. Instant coffee (240ml): 60-80mg. Black tea (240ml): 40-70mg. Green tea (240ml): 20-45mg. Red Bull (250ml): 80mg. Monster Energy (473ml): 160mg.
What time should I stop drinking coffee to sleep well?
With a 5-6 hour half-life, drinking coffee 6 hours before bed means roughly half the caffeine is still active. For good sleep, most sleep researchers suggest stopping caffeine 8-10 hours before your intended bedtime. If you sleep at 11 PM, that means no caffeine after 1-3 PM.