Black & green tea are produced from the same plant, Camellia sinensis, so both green and black tea naturally contain caffeine with both containing broadly similar amounts.

There are many types of tea containing different amounts of caffeine and the caffeine content of the beverage may vary widely depending upon brewing method and preferred strength.

On average tea contains 20-30 mg caffeine per 100 ml.

It is recommended that daily caffeine intake (all sources) should not exceed 600 mg/day, equivalent to 2-3 liter of tea/day. Pregnant women are however recommended to limit their daily caffeine intake from all sources to a maximum of 300 mg/day.

Herbal and Fruit 'teas' do not contain any caffeine. Fruit flavoured teas contain as much caffeine as normal black/green tea.