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Caffeine calculatorYour caffeine sweet spot
Not just a daily limit — find the amount that's best for focus, for exercise, and for your health, personalised to your body.
Your safe daily ceiling.
Your sweet spots
The right dose depends on your goal — all within your daily ceiling.
Heads up: caffeine takes ~5 hours to halve. See exactly how much is left at bedtime with the caffeine half-life calculator.
Educational estimate, not medical advice. Tolerance, medication, heart conditions and pregnancy all change your safe amount — talk to a doctor for personal guidance.
How much caffeine is right for you
There isn't one magic number — the best dose depends on what you're trying to do. Here's the science behind each sweet spot, all measured against your body weight.
🧠 For focus and brain
For alertness, reaction time and concentration, less is more. A moderate dose of about 1–2 mg per kg (roughly 75–150 mg, or one good coffee) gives near-maximal cognitive benefit. Pushing higher mostly adds jitter, anxiety and a faster crash — without making you sharper.
🏃 For exercise performance
Caffeine is one of the most evidence-backed legal performance aids. The established dose is 3–6 mg per kg taken 30–60 minutes before exercise — it improves endurance, strength output and perceived effort. It's a single pre-workout dose, so count it inside your daily total.
❤️ For health
For long-term health, the sweet spot is moderate, not maximum. Staying at or below 400 mg/day (about 2–4 cups), spreading it across the morning, and having your last cup at least 8 hours before bed gives you the lift without the sleep cost. Moderate coffee intake is associated with neutral-to-positive health outcomes in large studies.
Does sex matter?
The safe daily ceiling (≈400 mg) is the same for men and women — but two things differ. First, caffeine is dosed by body weight, so a lighter person reaches the same effect with less. Second, hormones change how fast you clear it: oral contraceptives can roughly double caffeine's half-life (so it lingers far longer and affects sleep more), and pregnancy slows it further — up to ~15 hours. That's why this calculator lets you flag birth control and pregnancy: it doesn't change your ceiling, but it changes your cutoff time.
Brew it accurately
Caffeine per cup depends on how much coffee you actually use. A scale makes “grams of coffee” real.
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Frequently asked questions
How much caffeine per day is safe?
Up to 400 mg/day for most healthy adults (about four 8 oz coffees), under 200 mg if pregnant or breastfeeding, and under ~100 mg for teens.
What's the best amount of caffeine for focus?
About 1–2 mg per kg — roughly 75–150 mg, or one good coffee. More than that adds jitter without sharpening you further.
How much caffeine before a workout?
The research-backed dose is 3–6 mg per kg, 30–60 minutes before exercise. For a 70 kg person that's ~210–400 mg — keep it within your daily limit.
Why does birth control change the result?
Oral contraceptives roughly double caffeine's half-life, so it stays in your system far longer. Your daily ceiling is the same, but you should stop caffeine earlier in the day to protect sleep.