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Caffeine for running calculator
How much caffeine to take before a race, and when, based on your bodyweight.
Short answer: Research supports 3–6 mg of caffeine per kg of bodyweight about 60 minutes before exercise, and low doses of about 3 mg per kg work well with fewer side effects. For healthy adults, keep single doses to about 200 mg and the day's total to 400 mg.
- About 60 min before the start
- 140 mg
- Second half of the race
- 70 mg
- From a caffeinated gel or drink
- Total from this plan
- 210 mg
- 210 mg from your bodyweight
Try caffeine on a long training run first: it can cause jitters, a racing heart, stomach upset or poor sleep. Skip it if you are pregnant, breastfeeding, have a heart condition or take medicines that interact with caffeine; ask a health professional instead. Nothing you enter is saved or sent anywhere.
How much caffeine should a runner take?
The International Society of Sports Nutrition reports that 3–6 mg per kg of bodyweight improves endurance performance in most people, and that lower doses, around 3 mg per kg, also work (Guest et al., 2021). Higher doses add side effects without clear extra benefit. The calculator starts at 3 mg per kg.
When to take caffeine before a race
Most studies give caffeine about 60 minutes before exercise (Guest et al., 2021). In longer races, saving some for the second half, from a caffeinated gel or cola, can help when tiredness builds. The calculator saves a third of the dose for races over 2 hours.
How much caffeine is safe?
The European Food Safety Authority found single doses up to 200 mg, and up to 400 mg a day, raise no safety concern for healthy adults. During pregnancy, the figure is 200 mg a day (EFSA, 2015). The calculator never takes your day above 400 mg.
Side effects and who should avoid caffeine
Caffeine can cause jitters, a fast heartbeat, an upset stomach and poor sleep. Try it on long training runs first. If you are pregnant, breastfeeding, have a heart condition or take medicines, ask a health professional before using it.
Scientific sources
- Guest N. S. 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.
- EFSA Panel on Dietetic Products, Nutrition and Allergies (2015). Scientific opinion on the safety of caffeine. EFSA Journal, 13(5), 4102.
More endurance tools and guides: Sports nutrition, including the race fuelling and hydration calculator.
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Educational information for adults aged 18 and over. It does not diagnose, treat or manage any medical condition. If you have a health condition, or symptoms that worry you, speak to your doctor or a health professional.