Caffeine in tea: green, oolong and black — how much of a lift is in your cup

Our nutritionist · September 27, 2026

Three cups of tea — green, oolong and black — on a wooden table

There is almost always caffeine in tea, but less than in coffee, and it works more gently. Here is how much caffeine is in green tea, black tea and oolong, what L-theanine has to do with it and how many cups a day is considered reasonable.

Caffeine in tea is the main reason a cup of tea perks you up. In Taiwan, China and Japan, people drink tea all day, and many notice that it gives steadier energy than coffee. There’s an explanation: both the amount of caffeine and the makeup of the drink are different.

How much caffeine in tea: green, black, oolong

On average, an 8-ounce (237 ml) cup of brewed black tea has about 47 mg of caffeine and green tea about 28 mg, while a cup of brewed coffee has about 96 mg (Mayo Clinic). Oolong usually falls between green and black (Caffeine Informer).

The numbers depend heavily on the variety, the amount of leaf, the water temperature and the steeping time.
The longer tea steeps, the more caffeine passes into the drink.
Repeat infusions of the same leaves usually contain less caffeine.

Caffeine in tea vs coffee: what’s the difference, and what does L-theanine in tea do?

The main difference lies not only in the amount of caffeine but also in L-theanine, an amino acid found in tea leaves. In a study combining caffeine and L-theanine, participants performed better on attention tasks and reported feeling more alert (study on PubMed). That’s why many people describe tea’s effect as “calm focus.”

How many cups of tea a day is a reasonable amount?

For most healthy adults, up to 400 mg of caffeine a day from all sources is considered safe (Mayo Clinic). But you need to count everything together: tea, coffee, cola, energy drinks and chocolate. How coffee affects sleep and how many cups count as normal is covered in our article Coffee and health, and other ways to stay alert in Daytime energy without coffee.

Tea is a good ally, but energy comes from sleep, food and movement. Some people start the morning with Cellergize Morning, a drink with vitamins and minerals, and during the day choose Energy Enhancer — according to LifeWave, it’s a patch for steady energy without caffeine.

Questions and answers

Which tea has the most caffeine?

Black tea usually has the most caffeine, green tea less, and oolong sits somewhere in between. But a lot depends on the variety, the amount of leaf and the steeping time.

Why does tea give a gentler lift than coffee?

A cup of tea contains less caffeine, and tea also contains the amino acid L-theanine. In studies, the combination of caffeine and L-theanine was linked to better concentration without a sharp buzz.

How many cups of tea a day can I drink?

For most healthy adults, up to 400 mg of caffeine a day from all sources is considered safe. In terms of tea that’s many cups, but you also need to count coffee, chocolate and energy drinks.

Can I drink tea in the evening?

It’s better to choose caffeine-free herbal drinks or weak tea. If you’re sensitive to caffeine, have your last cup of strong tea no later than midday.