Caffeine is the world's most popular performance supplement — and one of the most effective. Knowing your safe limit and an optimal pre-workout dose lets you use it wisely.
The performance dose
A dose of 3–6 mg per kilogram of bodyweight, taken roughly an hour before training, reliably improves endurance, power and perceived effort. More isn't better — higher doses mainly add side effects.
Respect the limits
Up to 400 mg/day is considered safe for healthy adults. Count every source and mind the timing: caffeine's long half-life means late-day intake can quietly wreck your sleep.
Frequently asked questions
Health authorities consider up to 400 mg per day safe for most healthy adults — roughly four cups of coffee. Individual tolerance varies, and pregnant people should stay under ~200 mg.
Research supports 3–6 mg per kilogram of bodyweight taken about 45–60 minutes before exercise. Start at the lower end to gauge your tolerance.
Caffeine has a half-life of around 5–6 hours, so half of a dose is still in your body that long after. Avoid it late in the day to protect sleep.