How much caffeine to take before and during your triathlon, from your body weight and race length, and when to take it, with the safe upper limits.
Before the race
210 to 420 mg
Take it about 60 minutes before the start, and try it in training first.
The top of this plan is over 400 mg for the day. Count your morning coffee and aim lower.
The International Society of Sports Nutrition position stand on caffeine (Guest et al., 2021) finds that 3 to 6 mg per kilogram of body weight consistently improves endurance performance, taken about 60 minutes before you start. The minimal effective dose is unclear, but the stand notes it may be as low as 2 mg per kilogram, so a smaller dose is a fair choice if you are sensitive. Very high doses (such as 9 mg per kilogram) bring more side effects without a clear extra benefit. The calculator shows the range and a 2 mg per kilogram option for your weight, rounded to 5 mg.
Habitual intake matters: regular coffee drinkers tend to respond less, and someone with almost none can feel a lot from a small dose. Start at the low end if you are unsure.
In a Half or a Full, a small second dose late in the race is a common way to stay sharp. The size shown, about 1 mg per kilogram, is our estimate and not a figure from the position stand. Caffeinated gels or a cola on the run are the usual way to take it.
The European Food Safety Authority (2015) and the FDA both put up to 400 mg a day at a level that is not a safety concern for healthy adults. EFSA also gives 200 mg as a single dose, which is below the ISSN range for many athletes (3 mg per kilogram is 210 mg at 70 kg), so lower doses are the cautious choice. Count the morning coffee and anything else you had before you add race caffeine. If you are pregnant, have a heart condition or take medication, ask a doctor first.
These are typical values, not exact: an espresso shot is about 60 to 80 mg, a brewed cup of 240 ml roughly 80 to 120 mg, and a caffeinated gel from about 25 to 100 mg. They vary by bean, brew and brand, so read the label on your gel.
Practise it before race day. Caffeine can bring on jitters, a racing heart or an upset stomach, and a late dose can wreck your sleep. Plan the rest of your fuel with the race fueling calculator and the drink mix calculator, and read triathlon nutrition basics.
The ISSN position stand supports 3 to 6 mg per kilogram of body weight, about 60 minutes before the start. For a 70 kg athlete that is roughly 210 to 420 mg. The minimal effective dose may be as low as 2 mg per kilogram, and you should try your dose in training first.
About 60 minutes before the start for the main dose. In a long race, a small top-up late on the bike or on the run is common. The size of that top-up is an estimate, so keep it small.
For healthy adults EFSA and the FDA both treat up to 400 mg a day as not a safety concern, and EFSA gives 200 mg as a single-dose figure. Count the coffee you had earlier in the day.
An espresso shot is typically 60 to 80 mg, a brewed cup about 80 to 120 mg, and caffeinated gels run from about 25 to 100 mg. These are typical values and vary by brand and brew, so check the label.
It can, but regular drinkers may respond less. Test what works for you in training and do not change your routine in race week.
