Free Tools
Caffeine Calculator
Enter your bodyweight and we'll show your effective pre-workout caffeine dose — then, because caffeine hangs around for hours, the latest time you can take it before bed without wrecking your sleep.
Caffeine is the one pre-workout ingredient that reliably works, at 3 to 6mg per kg of bodyweight. But it has a ~5 hour half-life, so timing matters as much as the dose. This tool handles both.
Enter your bodyweight — we'll show your effective caffeine range, then help you time it so it doesn't wreck your sleep.
Supplement tool
Creatine Dosage Calculator
Your exact loading and maintenance dose for your bodyweight, plus days to full saturation.
Supplement tool
Citrulline Dosage Calculator
The other big pre-workout active — how much of your form to take, and if your scoop underdoses it.
Nutrition tool
Protein Calculator
Get your daily protein target in grams for building muscle or losing fat, plus a per-meal split.
Your effective dose
Caffeine is the most reliable legal performance aid there is, and the effect scales with bodyweight — roughly 3 to 6mg per kg, taken half an hour to an hour before you train. A lighter person needs meaningfully less than a heavy lifter for the same buzz, which is why a fixed 300mg scoop hits a 60kg beginner very differently from a 100kg powerlifter. Start at the lower end, see how you respond, and never treat the label serving as gospel.
Why the half-life matters
Caffeine clears slowly — about a 5 hour half-life in a typical adult. Take 300mg for a 5pm session and you still have around 150mg on board at 10pm and 75mg at 3am. That lingering stimulant is the single biggest reason lifters who train late sleep badly, and poor sleep blunts recovery far more than a stronger pre-workout ever helped. If your training slot is in the evening, a stim-free pump product is almost always the smarter call.
Staying under the ceiling
Single servings up to 200mg raise no safety concern for healthy adults, and the daily ceiling is 400mg from every source combined — pre-workout, coffee, tea, energy drinks and cola all count. It is easy to blow past that on a heavy scoop plus a couple of coffees, so we mark any pre-workout that pushes a single serving over 400mg down in our scoring. More caffeine is not more gains; it is just more jitters, a higher heart rate and worse sleep.
Common questions
How much caffeine should I take before a workout?+
The studied performance range is about 3 to 6 milligrams of caffeine per kilogram of bodyweight, taken 30 to 60 minutes before training. For an 82kg lifter that is roughly 245 to 400mg. More is not better — past 400mg in a day the downsides tend to outweigh the extra benefit, which is exactly why our scoring penalises over-caffeinated pre-workouts.
What is the half-life of caffeine?+
In healthy adults caffeine has a half-life of roughly 5 hours, meaning half the dose is still in your system 5 hours after you take it, a quarter after 10 hours. It is longer if you are pregnant, on certain medications, or a slow metaboliser, and shorter in heavy smokers. That slow clearance is why an afternoon pre-workout can still be keeping you up at midnight.
When should I stop drinking caffeine before bed?+
A useful rule is to stop early enough that less than about 100mg is still circulating when you go to sleep. Because of the 5 hour half-life, a 200mg dose takes roughly 5 hours to fall to 100mg, and a 400mg dose takes about 10 hours. Enter your dose and bedtime above and the tool gives you the exact latest clock time to take it.
How much caffeine is safe per day?+
EFSA puts the safe daily limit for healthy adults at 400mg from all sources, and single doses up to 200mg raise no safety concern. Pregnant women should stay under 200mg a day. These are general figures for healthy adults, not medical advice — if you have a heart condition, anxiety, high blood pressure or take medication, speak to a clinician.
Does caffeine tolerance mean I should keep increasing the dose?+
No. Regular use blunts some of the alertness effect, but chasing it with ever-bigger doses just pushes you toward the side effects and wrecks your sleep, which harms training more than the caffeine helps. A better move is a short deload from stimulants every so often, or cycling stim-free pre-workout on lighter days, to reset sensitivity.
Now find your pre-workout
Know your number? See which pre-workouts actually hit an effective, sensible caffeine dose — and which ones bury an under-dosed scoop behind a huge proprietary blend. Every product is scored 0–100 on exactly that.
Informational only — not medical advice. Doses are general, evidence-based starting points for healthy adults; if you are pregnant, have a heart condition or take medication, speak to a clinician first. Buy links are affiliate links; we may earn a commission at no extra cost to you.