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Zuletzt aktualisiert am 06.11.2025
“I need a coffee first!”
Sound familiar? People in Germany drink more than 150 liters of coffee per year — per person! Sometimes that means you have your last cup a bit too late or let yourself be tempted into another even though you’ve had enough. Lying awake in bed, you end up asking: “What is caffeine’s half-life, and when can I finally sleep?”.
We’ll cover the key facts, and with our caffeine half-life table you can quickly see when your last cup of coffee will leave your body.
PS: Not sure what “half-life” even means? We got you! We’ll explain it clearly and quickly.
Your quick take: caffeine half-life
Caffeine’s half-life averages about 4 hours (3–5 h) but can range from 2 to 8 hours.
The amount of caffeine, your body weight, smoking status and many other factors can influence how fast caffeine is broken down.
Too much caffeine makes many people feel restless or nervous and can impair sleep according to expert bodies.
For healthy adults, 400 mg of caffeine per day is considered safe — that’s about 4–5 cups of coffee per day.
What is caffeine, anyway?
Before we dive into caffeine half-life, let’s briefly look at what caffeine actually is. Caffeine (also “coffeine”; German: Koffein) is a natural compound found in the fruits, leaves, or seeds of certain plants like coffee, cocoa, and tea plants. Most of us know caffeine as a “pick-me-up,” but it’s more widespread than you might think: not only do some teas contain caffeine — it’s also added to products like cola, energy drinks, sweets, or baked goods.
Caffeine is considered a psychoactive substance. Such substances influence consciousness and perception. That sounds dramatic, but it’s less so when you understand what it means. Many of us associate caffeine with exactly that stimulating, wakefulness-boosting effect.
Now, on to the big question: how long is caffeine’s half-life?
Caffeine half-life
So, what is the half-life of caffeine in the body?
The caffeine half-life indicates how long it takes for half of the ingested caffeine to be eliminated or broken down by the body.
In healthy adults, caffeine’s half-life is around 4 hours (3–5 h). There’s a big BUT: this time depends on many different factors such as age, smoking status, body weight, and more. That’s why the real caffeine half-life is individual and can vary from 2 to 8 hours.
How long it takes to break down caffeine — i.e., how long it stays in the body — also depends on the amount consumed. A cup of coffee (about 90 mg) contains more caffeine than a small glass of cola (about 40 mg), so, naturally, the breakdown takes longer.
Here’s the tricky bit: the half-life for a cup of coffee is the same as for a glass of cola, but after one half-life there are 45 mg of caffeine left from coffee versus only 20 mg from cola — because the amount always halves relative to what you started with.
Back to the average half-life of 4 hours: Does that mean caffeine stops working after 4 hours? No! How long does coffee — or caffeine — work? According to EFSA, caffeine’s effects usually begin 15–30 minutes after consumption and can last for different lengths of time. Some people feel nothing after a few hours; others still notice effects in the evening from a morning coffee.
Caffeine breakdown table
Want to know how quickly caffeine is broken down and how much remains a few hours after a cup of coffee? Our table gives you a ballpark figure.
Important: as noted earlier, breakdown rates are individual. Here we use the average half-life of 4h — yours may be faster or slower. Please don’t rely on it for precise decisions. Also, caffeine content varies with cup size and brew strength. So we can only use rough averages here.
Let’s start with the key question: how much caffeine is in one cup of coffee? On average about 90 mg, but 60–130 mg is possible.
Table: overview of caffeine half-life
If you’re wondering why, for example, 50 mg are broken down early on but later only 25 mg per 4 hours, here’s why: caffeine is not broken down by a fixed absolute amount each time — rather, a percentage of what’s in your system is broken down over a given period. So the absolute amount decreases over time.
FYI: When you no longer feel caffeine depends on your tolerance, body weight, time of day (many are more sensitive in the evening), etc. Most people stop noticing effects at blood levels under roughly 20–40 mg.
The right amount: too much caffeine?!
We’ve all been there: you sip coffee or cola throughout the day and suddenly it’s evening, you can’t sleep, and you’re asking: How much caffeine per day is actually too much?
For healthy adults, EFSA considers about 400 mg caffeine per day safe. That’s about 5.7 mg per kg body weight and roughly 4 cups of coffee a day. Don’t drink it all at once — better spread it out and preferably not too close to bedtime, or a sleepless night is likely.
For pregnant or breastfeeding people and for children, expert bodies recommend different limits:
Pregnant: max. 200 mg caffeine per day
Breastfeeding: max. 200 mg caffeine per day
Children & adolescents: max. 3 mg per kg body weight per day (ideally, kids should avoid caffeine altogether!)
And what happens if you overdo it?
If you have too much coffee once in a while, nothing dramatic will happen: you may sleep poorly, feel your heart racing, or feel nervous, restless, or anxious. That should pass soon. But if you regularly consume too much caffeine, serious consequences can follow — EFSA even associates it with cardiovascular issues.
So stick to the limit! If you just love the taste of coffee, decaf might be a good option. And if you feel you “need” coffee to get through the day, it might be worth taking a closer look at your lifestyle and sleep habits. Needing coffee isn’t a great sign.
By the way: if you often think “caffeine doesn’t work,” your body might simply be accustomed to it.
One more quick aside — not directly about half-life, but interesting:
Theine vs. caffeine
Surprise! Theine and caffeine are exactly the same substance. They just have different names because caffeine from coffee & co. is often described differently than caffeine from tea. To distinguish them, people used two names.
They’re often characterized like this:
Caffeine: stimulating, energizing, wake-promoting; short & intense
Theine: gently uplifting, balancing, focusing; long-lasting & mild
Both make you feel more awake and alert. Many people feel jittery after coffee, while tea drinkers report a calmer, smoother alertness. Why? Tea contains other compounds like L-theanine that modulate caffeine’s effects, often making them feel gentler.
Conclusion
We now know the caffeine half-life is about 4 hours — but it can be just over 2 or up to 8 hours. If you’re lying awake right now: it may still take a while until you can fall asleep. Pass the time with our blog articles or grab some tasty protein shakes — they’re at least as delicious as coffee but won’t steal your sleep.
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If you’ve had a bit too much coffee, feel free to come back here or just take a screenshot of our caffeine half-life table. That way, you’ll always know at a glance when you’re caffeine-free again.
Got questions? Send me an email — I’d love to hear from you! :)
The information in this article does not replace personalized medical or nutritional advice.
References & Sources
BfR (2017). Ergebnisse des Expertengesprächs „Mögliche Koffeinwirkungen auf das Herzkreislaufsystem von Kindern und Jugendlichen“. Bundesinstitut für Risikobewertung.
Dingermann, T. (2020). Gesünder als gedacht: Eine Neupositionierung von Kaffee und Koffein. Pharmazeutische Zeitung. Die Zeitschrift der Apothekerinnen und Apotheker.
Europäische Behörde für Lebensmittelsicherheit. (2015). EFSA erklärt Risikobewertung: Koffein. European Food Safety Authority.
