Caffeine Intake Calculator | Free Workout Tools

Q: How many cups of coffee a day are safe?

For healthy adults the guideline is up to 400 mg a day (about 4-5 cups of drip coffee) per EFSA and FDA. For lighter people, 5.7 mg per kg per day gives a lower number, so this tool shows the lower of the two.

Q: How much caffeine is in an energy drink?

It varies widely, from 80 to 300 mg per can depending on the product. Always check the label and count it toward your daily total together with coffee and tea.

Q: Does pre-workout caffeine actually work?

The ISSN position stand finds 3-6 mg per kg taken about 60 minutes before exercise effective for strength and endurance performance. Benefits and side effects vary between individuals, so start small.

Q: How long does caffeine stay in my system?

Caffeine’s half-life is about 3-7 hours (typically around 5). Finishing caffeine at least 6 hours before bed is a good rule for sleep quality.

Q: What about pregnancy and children?

During pregnancy the guideline is 200 mg a day or less; for children and adolescents about 3 mg per kg per day is the reference. This tool is for healthy adults - consult a doctor if in doubt.

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Body weight

Daily limit guideline (habitual intake, EFSA)

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Typical caffeine per serving

How to use the Caffeine Calculator

Caffeine is an everyday aid for focus and exercise performance, but too much causes insomnia, palpitations and anxiety. Safe amounts scale with body weight, so this tool calculates your daily and single-dose limit guidelines (based on the European Food Safety Authority’s assessment) and the pre-workout dose range considered effective (per the International Society of Sports Nutrition).

How to use this tool

Just enter your weight. Results show your daily and single-dose guideline limits, the effective pre-exercise range, coffee-cup equivalents, and typical caffeine contents of common drinks. Energy drinks vary hugely (80–300 mg per can) — always check the label.

Pre-workout caffeine

The ISSN position stand (2021) finds 3–6 mg per kg of body weight about 60 minutes before exercise effective for strength, muscular endurance and aerobic performance. Sensitivity varies a lot, so start at the low end if you are new to it. Caffeine late in the day hurts sleep quality — keep it at least 6 hours before bed if you want to protect your sleep cycles.

Tips

Coffee and tea also count toward hydration (see the Water Intake Calculator). For managing rest between sets after your pre-workout coffee, try the Interval Timer.

Glossary & FAQ

How many cups of coffee a day are safe?

For healthy adults the guideline is up to 400 mg a day (about 4–5 cups of drip coffee) (EFSA, FDA).

For lighter people, 5.7 mg per kg per day (EFSA) gives a lower number, so this tool shows the lower of the two as your guideline.

How much caffeine is in an energy drink?

It varies widely — 80–300 mg per can depending on the product.

Typical cans are 80–160 mg, but large or imported products can reach 300 mg. Always check the label, and count it together with coffee and tea toward your daily total.

Does pre-workout caffeine actually work?

The ISSN position stand finds 3–6 mg per kg taken about 60 minutes before exercise effective for strength, muscular endurance and aerobic performance.

Both benefits and side effects (palpitations, stomach upset) vary a lot between individuals, so start with a small dose.

How long does caffeine stay in my system?

Caffeine’s half-life is about 3–7 hours (typically around 5).

Half of an evening dose can still be in your body at bedtime, so finishing caffeine at least 6 hours before bed is a good rule for sleep quality.

What about pregnancy and children?

During pregnancy the guideline is 200 mg a day or less (EFSA, WHO); for children and adolescents, about 3 mg per kg per day is the reference.

This tool’s calculations are for healthy adults. If you are pregnant, breastfeeding or have medical conditions, consult a doctor.

Formulas & references
・EFSA Panel on Dietetic Products, Nutrition and Allergies. (2015). Scientific Opinion on the safety of caffeine. EFSA Journal, 13(5), 4102. (5.7 mg/kg/day habitual, 3 mg/kg single dose, 400 mg/day for adults, 200 mg/day in pregnancy)
・U.S. FDA. Spilling the Beans: How Much Caffeine is Too Much? (400 mg/day for healthy adults)
・Guest NS, et al. (2021). International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 18(1), 1. (3–6 mg/kg pre-exercise)
・Per-drink caffeine contents: approximate figures based on published values (Food Safety Commission of Japan fact sheet, etc.)

Please note
Results are guidelines for healthy adults based on public-agency publications and do not guarantee safety. Caffeine sensitivity varies greatly. If you are pregnant or breastfeeding, have heart disease, anxiety disorders or other conditions, or take medication, consult a doctor. Stop intake if you feel palpitations or dizziness.

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