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Caffeine intake calculator

Estimate a safe daily caffeine limit for a healthy adult.

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Enter Body weight (kg) and the Caffeine intake calculator works out Max daily caffeine, Cups of coffee straight away. For instance, with Body weight (kg) = 70 it returns Max daily caffeine = 400 mg and Cups of coffee = 4.211.

How to use it

  1. Enter your values: Body weight (kg).
  2. Read the result instantly: Max daily caffeine, Cups of coffee.

Frequently asked questions

What does the Caffeine intake calculator actually compute?

It takes Body weight (kg) and derives Max daily caffeine and Cups of coffee from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

A single value: Body weight (kg). Nothing else is required — no account, no file upload.

Can you show a worked example?

With Body weight (kg) = 70, the calculator returns Max daily caffeine = 400 mg and Cups of coffee = 4.211. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What does it give for smaller values?

Scaled down to Body weight (kg) = 63, Max daily caffeine comes out at 378 mg. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Working backwards from the hour you have to be up: when to go to bed so an alarm does not land in the middle of deep sleep, how long a nap can run before it starts costing more than it gives, and how late a coffee still counts.

What is the most common mistake?

Treating the cycle length as a fact about you. Ninety minutes is an average, and a real cycle runs anywhere from about seventy to a hundred and ten minutes and changes across the night — so a bedtime computed here is a better guess than the round hour, not a wake-up guarantee. The time it takes to fall asleep is the other half, and it is the part people leave out.

How accurate is it, and what are the limits?

For general information only — not medical advice. Based on the FDA ceiling of about 400 mg/day for healthy adults (~6 mg per kg of body weight, roughly 95 mg per cup of coffee). Pregnant people, adolescents and those with certain conditions should aim much lower; consult a healthcare professional.

What is the difference between the Caffeine intake calculator and the Daily sugar intake calculator?

This one returns Max daily caffeine and Cups of coffee; the Daily sugar intake calculator returns Maximum sugar (10% of energy) and Ideal sugar (5% of energy). That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Protein intake calculator is the closest one after this: Estimate your daily protein needs from your body weight and activity.

What else is worth having open alongside it?

Water intake calculator and Baby Milk Intake Calculator — they come up in the same task often enough to be worth a second tab.

Further reading

All guides →
ExplainerHow Much Caffeine Is Safe Per Day?The 400 mg daily guideline for adults, how much caffeine is in coffee, tea, cola and energy drinks, and why sensitivity varies from person to person.ExplainerCaffeine Against Sleep Pressure: What It Blocks, and What It CannotSleep is regulated by two processes: a pressure that builds with every waking hour, and a clock. Caffeine acts on neither directly — it blocks the receptors that report the pressure. The pressure keeps building behind the block, which is why the crash arrives and why an afternoon dose costs that night's sleep even when you do not feel it.ExplainerCaffeine Half-Life: Why Your Afternoon Coffee Is Still There at MidnightCaffeine leaves by first-order kinetics, so what remains is the dose times one half to the power of elapsed time over half-life. The half-life is not a constant — it varies by multiples between people, and that is the whole story.ExplainerHow Much Fiber Per Day Do You Need?Daily fiber targets of 25 to 38 grams by sex and age, why fiber matters for digestion and heart health, and the best food sources to hit your goal.ExplainerHow Much Sodium Per Day Is Safe?The 2,300 mg FDA limit, the 1,500 mg ideal from the AHA, and why most sodium is hidden in packaged food — plus how to read labels and cut back.ExplainerHow Much Sugar Per Day Is Healthy?The WHO limit on free sugars, how to turn a percentage of calories into grams, and where hidden sugar comes from — with practical daily targets.