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.
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Caffeine Guide
What's the key thing to understand about 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.
What do I need to know about 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.
What's the key thing to understand about 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.
What do I need to know about 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. Regular high intake also raises baseline anxiety and can worsen sleep quality, even on nights without caffeine consumed late in the day.