*Source: https://www.years.co/en/koffein-rechner*

Caffeine calculator

# How long does caffeine last?
Caffeine has an average half-life of roughly 5 hours. So after 5 hours half of the amount you consumed is still active in your body, and after 10 hours a quarter. Work out below how much caffeine is still active at your bedtime.

Caffeine calculator

## How long does your caffeine last?

Choose a drink Espresso Drip coffee (250 ml) Cappuccino Black tea Green tea Matcha Energy drink (250 ml) Cola (0.33 l)

Caffeine amount 95 mg

EFSA guidance: up to 400 mg per day is considered safe for healthy adults.

Metabolism profile Standard Smoker Contraceptive pill / pregnancy

Half-life 5 h — median in healthy adults.

Last dose before sleep

9 h 38 min

beforehand, so that less than ~25 mg of caffeine remains (sleep-friendly).

Remaining caffeine over time

0 h

95 mg

1 h

83 mg

2 h

72 mg

3 h

63 mg

4 h

55 mg

6 h

41 mg

8 h

31 mg

10 h

24 mg

12 h

18 mg

Have sleep & performance measured

Estimate based on average half-lives. Individual caffeine metabolism varies widely (genetics/CYP1A2, liver function, medication). Not medical advice. No inputs are stored.

## What influences caffeine half-life

### Genetics (CYP1A2)
Metabolism runs almost entirely through the liver enzyme CYP1A2. Its activity is genetically determined — “fast” and “slow” metabolisers respond to the same cup completely differently.

### Smoking
Nicotine induces CYP1A2 and shortens the half-life to around 3 to 4 hours. After quitting, metabolism slowly returns to normal.

### The pill & pregnancy
Oestrogens inhibit metabolism. In late pregnancy the half-life can rise beyond 15 hours — and caffeine acts correspondingly longer.

### Time of day & sleep
Caffeine blocks adenosine receptors and so suppresses tiredness. Drinking too much in the afternoon pushes back sleep onset and shortens deep sleep, often without you noticing.

## Frequently asked questions about caffeine
How long does caffeine stay in the body? → Caffeine has an average half-life of around 5 hours. So after 5 hours half of the amount consumed is still active, and after 10 hours a quarter. The individual range runs from 1.5 to more than 9 hours, depending on genetics, smoking, pregnancy and medication.

How is caffeine half-life calculated? → Caffeine is metabolised exponentially. From the starting amount and the half-life, the remaining amount follows the formula: remaining caffeine = starting amount × 0.5^(hours / half-life). With a half-life of 5 hours, 200 mg leaves 100 mg after 5 hours and 50 mg after 10 hours.

When should I have my last coffee? → As a rule of thumb, take your last caffeinated dose around 6 hours before going to bed. Studies show that even 400 mg of caffeine 6 hours before bedtime can measurably shorten sleep duration. If you are sensitive or metabolise caffeine slowly, allow more time.

Why does caffeine not clear at the same rate in everyone? → Metabolism runs predominantly through the liver enzyme CYP1A2, whose activity differs genetically. Smoking speeds it up; oestrogens (the pill, pregnancy) slow it down considerably. That is why the same cup acts hours longer in some people than in others.

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