The short version
- For healthy adults, the FDA says about 400 mg a day is not generally associated with negative effects.
- That is about four or five cups of brewed coffee, but drinks vary widely.
- Caffeine late in the day can hurt sleep. Pregnant people and some medical conditions need different limits.
Caffeine can make training feel easier. The ISSN’s 2021 position stand found it can improve many kinds of exercise performance. More is not better, though.
The 400 mg guide
The FDA says 400 mg a day, roughly four or five cups of coffee, is an amount not generally associated with dangerous effects in healthy adults. People vary in sensitivity, and some medications interact with caffeine.
Watch out for
- Energy drinks and pre-workout powders can contain a lot of caffeine per serving. Read the label.
- Pure or highly concentrated powdered caffeine. The FDA warns these can be dangerous.
- Caffeine within several hours of sleep, especially for shift workers. See sleep tips for night shift workers.
Do this today
Add up your caffeine for one day: coffee, tea, soda, energy drinks and pre-workout.
Questions people ask
How much caffeine is in a cup of coffee?
It varies widely by brew and size; an 8-ounce cup is often around 80 to 100 mg.
Is caffeine before a workout okay?
For many healthy adults, yes. Start low and avoid it close to bedtime.
Who should limit caffeine more?
People who are pregnant or breastfeeding, those with heart conditions, anxiety or on certain medications should ask a clinician.
Sources
- U.S. FDA. Spilling the Beans: How Much Caffeine Is Too Much? Checked October 9, 2026.
- Guest NS, et al. ISSN position stand: caffeine and exercise performance. J Int Soc Sports Nutr, 2021. Checked October 9, 2026.
- NIH NHLBI. How Much Sleep Is Enough? Checked October 9, 2026.
Education only. Not medical or dietary advice. If you have a health condition, are pregnant or breastfeeding, take medication, or are under 18, check with your clinician or a registered dietitian before changing your diet or taking supplements.
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