Caffeine Calculator: free race caffeine dose calculator.
Enter your weight and your race start. Get your caffeine dose in mg, when to take it, and what that is in coffee or gels.
Your caffeine
Race at 9:00
Before the race
210 to 400mg
The research range is 3 to 6 mg per kg. 6 mg per kg would be 420 mg, over the 400 mg a day EFSA sees as safe for healthy adults, so the range stops at 400.
Guest 2021EFSA 2015Take it at
8:00
About 60 minutes before the start, the timing most studies use. Caffeine gum works faster, so it needs less of a wait.
Guest 2021The low end, 210 mg, is about
- 2½cups of filter coffee (200 ml, about 90 mg)
- 2½espressos (60 ml, about 80 mg)
Caffeinated gels carry what their label says: that is 4 gels at 50 mg, or 2 at 100 mg. Coffee varies a lot from cup to cup, so a gel or a caffeine tab is easier to dose. EFSA caffeine
Your habit doesn't change the range: the research found no consistent difference in the effect between regular and occasional users. Guest 2021
EFSA found single doses up to 200 mg raise no safety concerns for healthy adults, even within 2 hours of hard exercise in normal conditions, and up to 400 mg a day from all sources. Racing late? Even 100 mg can affect sleep when taken close to bedtime. EFSA 2015
Not for anyone pregnant, breastfeeding or under 18. Talk to your doctor first if you have a heart condition, high blood pressure, anxiety, or take medication.
Hand it to your AI
Your AI can check these numbers against your training and adjust them. The prompt has your results filled in.
See the prompt
I weigh 70 kg, my race starts at 9:00, and my usual caffeine is: a cup or two a day. A caffeine calculator based on the ISSN position stand (Guest 2021) gave me 3 to 6 mg per kg, about 60 minutes before: 210 to 400 mg, taken at 8:00. EFSA puts the safe daily total for healthy adults at 400 mg from all sources. Help me test this in a key training session first: what to take, in which form (coffee, gel, caps), when, and how to count my other caffeine that day. Ask me how caffeine affects my sleep and stomach.
Gemini, Grok Bot, Dots, Muse and Cue: copy the prompt and paste it in.
Your AI could test this with you in training. Join Memory.fit.
On Android now: get it on Google Play. One email when the iPhone app is on the App Store.
How it works
How the Caffeine Calculator works.
Caffeine has strong evidence behind it for endurance performance. The ISSN position stand puts the dose that works at 3 to 6 mg per kilogram of body weight, most often taken about 60 minutes before the start. The smallest dose that helps may be as low as 2 mg per kilogram. Very high doses, around 9 mg per kilogram, bring a high rate of side effects and no extra benefit, so the calculator never goes above 6.
There is a safety line for the whole day too. EFSA found up to 400 mg a day from all sources safe for healthy adults, and single doses up to 200 mg, even within 2 hours of hard exercise. So the range stops at 400 mg, and your breakfast coffee counts toward it. Pregnancy is different, with a line of 200 mg a day, and this calculator is not for anyone pregnant or under 18.
People respond very differently, through their genes, their habits and how sensitive they are to sleep loss and anxiety. Try your dose in a hard training session before race day. If you race late, remember that caffeine close to bedtime can cost you sleep.
The formula
- caffeine (mg) = 3 to 6 mg × body weight (kg), never above 400 mg a day
- take it at = race start − 60 minutes
- cups of filter coffee = dose ÷ 90 mg (EFSA's figure for a 200 ml cup)
The science
Where the numbers come from.
These are the same rules Memory.fit's engine uses when your AI asks it for a number, read from one registry of cited sources.
Guest NS, VanDusseldorp TA, Nelson MT, et al. International Society of Sports Nutrition position stand: caffeine and exercise performance (2021). Journal of the International Society of Sports Nutrition 18(1):1.
Position stand · 2021 · doi:10.1186/s12970-020-00383-4
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific Opinion on the safety of caffeine. EFSA Journal 13(5):4102.
Scientific opinion · 2015 · doi:10.2903/j.efsa.2015.4102
European Food Safety Authority. Caffeine (topic page: safe intakes and the caffeine in common drinks).
Fact sheet · Read it
Example
A worked example.
A 70 kg runner with a 9:00 race start who drinks a coffee or two most days.
- 13 to 6 mg per kg × 70 kg = 210 to 420 mg. 420 mg is over EFSA's 400 mg a day, so the range is 210 to 400 mg.
- 2About 60 minutes before a 9:00 start, so take it at 8:00.
- 3The low end, 210 mg, is about 2½ cups of filter coffee at 90 mg each, 2½ espressos at 80 mg, or 2 gels with 100 mg each.
- 4Their usual coffee counts toward the 400 mg for the day, so the race dose and breakfast coffee together stay under it.
Questions
Caffeine Calculator: questions.
The research range is 3 to 6 mg per kilogram of body weight, about 60 minutes before the start. For a 70 kg athlete that is 210 to 420 mg, held at 400 mg because that is the daily safety line for healthy adults. Start at the low end in training.
Most studies use about 60 minutes before. The ISSN position stand notes the best timing depends on the source: caffeine gum works faster, so it needs less of a wait than a capsule or coffee.
No. Doses around 9 mg per kilogram bring a high rate of side effects and no extra benefit. That is why the calculator stops at 6 mg per kilogram.
The research found no consistent difference in the effect between people who drink caffeine every day and people who rarely do, so the dose range is the same. Your usual coffee still counts toward the 400 mg for the day.
EFSA's figures: about 90 mg in a 200 ml cup of filter coffee, 80 mg in a 60 ml espresso, 80 mg in a 250 ml energy drink. Real cups vary a lot, so a gel or a caffeine tab with the amount on its label is easier to dose.
No. EFSA's 400 mg a day is for healthy adults. In pregnancy and while breastfeeding the line is 200 mg a day, and for children and teens it is 3 mg per kg a day. This calculator is not for anyone pregnant or under 18. If you have a heart condition, high blood pressure or take medication, talk to your doctor first.
Not medical advice. These numbers come from published research on groups of athletes. Your own needs can differ; talk to a doctor or a sports dietitian about any health condition.