When should I take pre-workout?
An hour before you train, and early enough that it's gone by bedtime. An evening scoop is still about half in you when you fall asleep.
254 mg is the average of the top 100 products. Check your label.
245 to 490mg, the studied range for 180 lb
About 165 mg (2 mg per kg) may be enough. 3 to 6 mg per kg consistently helped performance in the studies, and 9 brings side effects without adding anything.
- Latest start, full scoop
- 9:55am
- Latest start, half a scoop
- 2:55pm
Half a scoop buys you 5 hours. Both leave under our 40 mg line at sleep, taken an hour before you start.
Not for anyone under 18, pregnant, with a heart rhythm problem, or on a stimulant prescription (ask your prescriber).
What your result means
- Your scoop is inside the 3 to 6 mg per kg range: that's the dose the studies found helps. You don't need more.
- Your scoop is above it: you're taking more than the studies needed. A smaller scoop brings it down, and at 9 mg per kg the side effects pile up without adding anything.
- What's left at bedtime is over 40 mg: the session is too late for a full scoop. Try half, or start earlier, or train on coffee from the morning.
What to do next
- Check your label, since products vary a lot around the 254 mg average.
- Try about 2 mg per kg first. It may be enough, and it leaves the least in you tonight.
- Coffee works too. The studies tested caffeine, and an 8 oz coffee is a dose you know, about 95 mg. After a short night the tiredness is still there under any scoop, and how to have more energy without caffeine starts with sleep.
The studied dose by weight
| Weight | 3 to 6 mg per kg | 2 mg per kg |
|---|---|---|
| 130 lb | 175 to 355 mg | 120 mg |
| 150 lb | 205 to 410 mg | 135 mg |
| 180 lb | 245 to 490 mg | 165 mg |
| 210 lb | 285 to 570 mg | 190 mg |
| 240 lb | 325 to 655 mg | 220 mg |
A scoop by session time, asleep at 11pm
Taken an hour before you start, on a 5 hour half-life. The latest start for a full 254 mg scoop that leaves under 40 mg is 9:55am.
| Session starts | Full scoop, left at 11pm | Half a scoop |
|---|---|---|
| 7:00am | 27 mg | 13 mg |
| 10:00am | 40 mg | 20 mg |
| 1:00pm | 61 mg | 31 mg |
| 4:00pm | 93 mg | 46 mg |
| 6:00pm | 123 mg | 61 mg |
| 8:00pm | 162 mg | 81 mg |
What the studies found
The International Society of Sports Nutrition's 2021 position: 3 to 6 mg of caffeine per kg of body weight consistently improves performance, usually taken 60 minutes before exercise. The lowest effective dose may be about 2 mg per kg, and 9 mg per kg brings many side effects without being needed. The top 100 pre-workout products averaged 254 mg a serving, and they vary a lot, so check your label.
3 sources
- Guest NS and others, International society of sports nutrition position stand: caffeine and exercise performance, Journal of the International Society of Sports Nutrition, 2021doi.org
- Jagim AR, Harty PS, Camic CL, Common Ingredient Profiles of Multi-Ingredient Pre-Workout Supplements, Nutrients, 2019doi.org
- Antonio J and others, Common questions and misconceptions about caffeine supplementation: what does the scientific evidence really show? Journal of the International Society of Sports Nutrition, 2024doi.org
