Caffeine Calculator
Add your drinks to calculate total daily caffeine intake. See if you're within safe limits, when caffeine will leave your body, and how different sources compare.
Add your drinks today FDA safe limit: 400mg
Or enter a custom amount:
mg
lbs
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mg caffeine consumed
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% of 400mg limit
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mg per kg bodyweight
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Hours until cleared
Safety level vs FDA 400mg daily limit
0100mg200mg300mg400mg+
Caffeine in your system over time
Common caffeine sources (mg)
| Source | Serving | Caffeine | vs your intake |
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FAQs
How much caffeine is safe per day? ›
The FDA considers 400mg/day safe for healthy adults (roughly 4 cups of brewed coffee). At 6mg/kg/day, adverse effects begin. For pregnant women: 200mg/day (American College of OB-GYN). For adolescents: 100mg/day maximum. Energy drinks can contain 80–300mg per can. Caffeine sensitivity varies — genetics, medications, liver health, and tolerance all affect how your body processes it. Signs you've had too much: jitteriness, anxiety, rapid heartbeat, insomnia, headache, irritability.
How long does caffeine stay in your system? ›
Caffeine has a half-life of 5–6 hours in most adults (range: 1.5–9 hours). This means half the caffeine from your morning coffee is still in your system at noon. After one full half-life (~5 hours), 50% remains. After two half-lives (~10 hours), 25% remains. After three (~15 hours), ~12.5% remains. To minimize sleep disruption, avoid caffeine at least 6 hours before bedtime — many sleep experts recommend stopping by 2 PM. Certain medications (oral contraceptives, some antibiotics) can extend caffeine's half-life significantly.