Caffeine in tea: what affects the amount in your cup

Tea contains the same caffeine molecule as coffee; “theine” is an old name for it. A tea’s name or liquor colour cannot tell you the exact dose. White tea, shu pu-erh and GABA oolong all contain caffeine.

Jin Jun Mei tea in a small tasting cup.
Photo: Difference engine · CC BY-SA 4.0

Check the amount in a brewed serving

As a rough guide, EFSA gives about 50 mg in 220 ml of black tea, called red tea in the Chinese classification. This is an example, not a value for every cup. Package figures are useful when they specify serving size and preparation. Caffeine in dry leaves is not the same as caffeine in the infusion you drink.

Count the whole session

The leaves, how much you use, the water and the steeping time all affect caffeine in the cup. Shorter infusions usually extract less from the same leaves, but the amount adds up over several rounds. Count the whole session, especially if you add fresh leaves.

Do not rely on home decaffeination

Rinsing removes some soluble material but does not turn tea into decaf; there is no universal removal percentage for 30 seconds. Mild flavour, age and mature leaves do not guarantee low caffeine. Theanine and GABA do not cancel caffeine’s possible effects on sleep or heart rate.

Reduce intake when needed

Try less leaf and less tea overall, and drink it earlier. For a more predictable reduction, choose decaffeinated tea with manufacturer information; some caffeine can remain. Count coffee, energy drinks, cola and caffeine-containing medicines too.

Questions and answers

How much caffeine is acceptable in a day?

EFSA identifies up to 400 mg spread across a day and up to 200 mg in one dose as levels of no safety concern for most healthy adults. These are not targets or guarantees against symptoms. During pregnancy, keep total intake to no more than 200 mg daily; medical conditions and medicines may call for individual advice.

What if I feel shaky or sleep poorly?

Reduce caffeine and move it earlier. Discuss recurring or substantial symptoms with a clinician rather than assuming every symptom comes from tea.