Caffeine before a workout: how much to take for your weight, when, and what it really improves

Published on 27 September 2026

Taking 3 to 6 mg per kilo an hour beforehand improves strength, muscular endurance and above all cardio, but much smaller doses already work. A dose table by weight, how much caffeine each drink contains, the effect of genetics and the limit so you don't sleep worse.

For a 70-kilo person, the caffeine dose that studies link to better performance is between 210 and 420 milligrams: two to four coffees. Taken an hour before training, it improves strength slightly, muscular endurance a bit more and aerobic endurance quite a lot. Alongside creatine, it's the supplement with the most evidence in sport, and you probably already have it in your kitchen.

Here's how much caffeine to take before training based on your weight, when to take it, what it really improves, why it doesn't work for some people and where the limit is so it doesn't take a toll on your sleep or your health.

What caffeine before a workout actually improves

Caffeine blocks adenosine receptors. Adenosine is a molecule that builds up over the day and during exertion and increases the feeling of tiredness. The result is that the same work feels somewhat easier and your nervous system recruits muscle more effectively.

The umbrella review by Grgic and colleagues (2020) brought together 21 meta-analyses and concluded that caffeine improves aerobic endurance, strength, muscular endurance, power, jumping and speed. The effect is usually larger in aerobic than in anaerobic exercise. Along the same lines, the official position stand of the International Society of Sports Nutrition (ISSN, 2021) describes small to moderate benefits for strength and muscular endurance, and moderate to large, more consistent benefits for aerobic endurance.

Small doesn't mean useless. In the gym, one or two extra reps per set or a few more kilos on your best set, repeated over weeks, add up. But don't expect miracles: caffeine is no substitute for good sleep or a good programme.

How much caffeine to take before a workout, by body weight

The ISSN puts the effective dose at 3-6 mg per kilo of body weight. Very high doses, around 9 mg/kg, send side effects soaring without improving performance. And there's good news if you don't tolerate much coffee: the meta-analysis by Grgic (2022), with 12 studies that used only between 0.9 and 2 mg/kg, found improvements in strength, muscular endurance and bar velocity similar in size to those of higher doses.

*The marked figures exceed the 400 mg a day that the European Food Safety Authority (EFSA) considers safe for a healthy adult, without counting the rest of your coffee that day. In practice, start with 2-3 mg/kg: you get almost all the benefit with far fewer side effects.

When to take caffeine before a workout

The timing most used in studies is 60 minutes before exercise, which is when caffeine from capsules or coffee reaches high levels in the blood. The ISSN points out that the ideal timing depends on the form: caffeinated chewing gum acts sooner and can be taken closer to the start. With coffee or a liquid pre-workout, 30 to 60 minutes beforehand is a reasonable window.

Coffee, capsules or pre-workout: how much caffeine each one contains

What matters is the dose, not the source. According to EFSA's reference figures, a filter coffee of about 200 ml contains around 90 mg of caffeine, a 60 ml espresso about 80 mg, a 250 ml energy drink about 80 mg and a 220 ml cup of black tea about 50 mg. The problem with pre-workouts isn't the caffeine itself, but that many contain high doses (sometimes 300 mg or more per serving) mixed with other stimulants, and it's easy to overdo it once you add the day's coffee. Capsules have the advantage that you know exactly how much you're taking.

Why caffeine doesn't work for some people

The response to caffeine varies a lot from person to person, and part of that variation is genetic. The CYP1A2 gene determines how quickly your liver metabolises caffeine. The meta-analysis by Barreto and colleagues (2024), with 13 studies and 440 participants, found that caffeine improved performance in people with the AA and AC genotypes, but worsened it in those with the CC genotype, the slow metabolisers. It's worth taking this with caution: there were only 34 people with that genotype and, when studies with declared conflicts of interest were excluded, the influence of genotype disappeared. It's a clue, not a rule.

And what if you drink coffee every day? It's a common question, and the evidence is reassuring. In the study by Grgic and Mikulic (2021), trained men with a low daily caffeine intake (about 65 mg) and others with a fairly high one (about 235 mg) took 3 mg/kg before training. Caffeine improved most of the tests, with 1.2 more reps on the bench press on average, and habitual intake didn't change the effect in any of them.

You don't need a genetic test: if caffeine makes you jittery, speeds up your heart or you notice you train worse, try a lower dose or skip it. Your own response is the best indicator.

Caffeine and sleep: the afternoon cut-off

This is the real cost if you train in the afternoon or evening. In the study by Drake and colleagues (2013), 400 mg of caffeine significantly disrupted sleep whether taken at bedtime or 3 or 6 hours earlier, and the authors concluded that large doses should be avoided for at least 6 hours before going to bed. Since sleep is where much of your recovery is consolidated, gaining a little performance at the cost of sleeping worse is a bad deal; we explain it in sleep and athletic performance.

• If you train in the morning or at midday: you can use the usual dose without any problem.
• If you train from 17:00-18:00 onwards and go to bed early: use low doses (1-2 mg/kg) or skip caffeine.
• If you notice you sleep worse on training days: take it earlier or lower the dose before thinking about other supplements.

How much caffeine is too much

EFSA considers up to 400 mg of caffeine a day safe for healthy adults, and up to 200 mg in a single dose. During pregnancy and breastfeeding the limit drops to 200 mg a day. The most common side effects of overdoing it are jitteriness, a racing heart, digestive discomfort and insomnia. If you have high blood pressure, arrhythmias or anxiety, or you take medication, check with your doctor before using caffeine as a supplement.

How to use caffeine for training: a practical summary

• Dose: start with 2-3 mg/kg. Going up to 6 mg/kg is rarely worth it.
• Timing: 45-60 minutes before; with gum, a bit closer.
• Source: coffee or capsules. If you use a pre-workout, check how much caffeine each serving contains.
• Limit: 400 mg a day counting everything, and nothing substantial in the 6 hours before bed.
• Priorities: caffeine fine-tunes, it doesn't build. First training, enough protein and rest; then supplements such as creatine and caffeine.

If you want to see which other supplements have evidence behind them and which don't, we go through them in supplements for building muscle according to science. And to decide what to eat before your session, there's our guide on what to eat before training.

If you want to turn this into a specific routine, the Progrevia routine generator builds one for free in under a minute, adapted to your goal, level and equipment.

Progrevia · Updated 27 September 2026 · How we write our guides

Informational content based on the available scientific evidence: it does not replace advice from a healthcare professional. If you have an injury or a medical condition, or are pregnant, check with one before changing your training or diet.