Caffeine Intake Calculator
Calculate your total daily caffeine from all sources and find out if you're over the safe limit — and what time you should have your last coffee.
Caffeine Guide
Safe Caffeine Limits
The European Food Safety Authority considers 400mg/day safe for healthy adults — roughly 4 espresso shots or 3–4 mugs of filter coffee. For pregnant women, the NHS recommends no more than 200mg/day. For adolescents, the EFSA recommends under 3mg/kg bodyweight per day (approximately 200mg for a typical teenager). Typical caffeine content: espresso shot 60–80mg, 250ml filter coffee 80–120mg, mug of tea 50–75mg, 250ml energy drink 75–80mg (Red Bull), 330ml cola 35mg.
Caffeine Half-Life and Sleep
Caffeine has a half-life of approximately 5–6 hours. Coffee drunk at 2pm still has 50% of its caffeine active at 7–8pm, and 25% at midnight. This is why sleep researchers recommend no caffeine after 12–14 hours before target bedtime — for someone who sleeps at 11pm, the cut-off is 9–11am. The sleep-disrupting effects of caffeine often go unnoticed because tolerance develops, but sleep quality (particularly slow-wave deep sleep) is measurably impaired even when falling asleep feels normal.
Caffeine Sources Ranked
Highest to lowest caffeine per serving: espresso-based (60–80mg per shot), death wish / strong ground coffee (150–200mg per cup), energy drinks like Bang (300mg/can), filter coffee (80–120mg), matcha (70mg per serving), black tea (50–75mg), green tea (30–50mg), cola (35mg/330ml), milk chocolate (20mg/50g), decaf coffee (3–15mg — not zero). Supplement pre-workouts often contain 150–300mg caffeine per serving — always check labels.
Caffeine Sensitivity and Tolerance
Caffeine sensitivity varies considerably with genetics. Variants in the CYP1A2 gene affect how quickly caffeine is metabolised — fast metabolisers can tolerate more without side effects; slow metabolisers experience stronger and longer-lasting effects. Regular consumption leads to tolerance — reducing alerting effects while maintaining sleep disruption. A 5–7 day caffeine withdrawal period resets tolerance, typically involving 2–3 days of headaches and fatigue before improved baseline energy. Re
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