How to use
- 1Enter your body weight (kg or lb) and pick a dose; the ISSN range is 3–6 mg per kg.
- 2Choose your group (adult, pregnant or breastfeeding, under 18) and enter caffeine you have already had today.
- 3Add your workout time and bedtime to see when to take it and how much is still in your body at night.
- 4Check the table to see your dose as cups of coffee, mugs of tea, cans of energy drink or cola.
Caffeine dose for performance
The International Society of Sports Nutrition’s 2021 position stand on caffeine (Guest et al.) concludes that 3–6 mg per kg of body mass consistently improves performance, most clearly in endurance exercise, and that doses as low as 2 mg/kg can work for some people. Very high doses around 9 mg/kg bring more side effects without extra benefit. It is most commonly taken about 60 minutes before exercise; gum and other fast-absorbing forms work sooner.
Safe daily limits
The European Food Safety Authority (EFSA, 2015) considers up to 400 mg a day safe for healthy adults, with single doses up to 200 mg raising no concern. For pregnant and breastfeeding women the limit is 200 mg a day, and for children and teenagers 3 mg per kg per day. The calculator subtracts what you have already had and warns when a dose would take you over your limit.
Coffee, tea and sleep
A mug of filter coffee has roughly 90 mg, a single espresso about 65 mg, a mug of black tea about 50 mg and a 250 ml energy drink about 80 mg; brewing and brand change the numbers. Caffeine’s half-life is around 5 hours, so a 6 pm pre-workout dose can still be in your system at midnight. If your sleep suffers, lower the dose or train earlier. This tool is for information only and is not medical advice.
Frequently asked questions
How much caffeine should I take before a workout?
The ISSN range is 3–6 mg per kg. At 70 kg (154 lb) that is 210–420 mg; start at the low end and keep single doses at or below 200 mg if you are new to it.
How many cups of coffee is 400 mg?
About four 200 ml mugs of filter coffee at roughly 90 mg each, or around six single espressos. Add tea, cola and energy drinks to the total too.
How long before exercise should I take caffeine?
Blood levels usually peak within 30–60 minutes, so the calculator suggests taking it 60 to 30 minutes before you start.
Can I have caffeine while pregnant?
EFSA advises staying under 200 mg a day during pregnancy and breastfeeding; dosing for performance is not recommended. Ask your doctor.
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