Caffeine in Black tea
A 240 ml mug of black tea holds about 48 mg of caffeine, half a filter coffee.
| Caffeine per serving | 48 mg |
| Serving | 8 oz cup (240 ml) |
| Caffeine per 100 ml | 20 mg |
| Share of the 400 mg daily limit | 12% |
| Equal to filter coffee | 0.5 mugs |
| Equal to espresso | 0.8 shots |
| Time to fall below 40 mg | 1 and a half hours |
How long does it last?
How late can you have it?
For an average metabolism this drops below the 40 mg sleep threshold about 1 and a half hours after you drink it, so the latest you could have one and still be clear by an 11 pm bedtime is 9:18 pm. A fast metaboliser gains roughly two hours, a slow one loses two.
What to know
Brew time drives the number more than the blend does. Two minutes gives roughly 35 mg, five minutes closer to 60 mg from the same bag. Squeezing the bag adds a little more.
A strong builder's tea with a long steep is not far off an espresso. Six mugs across a day is a real 300 mg, which is why heavy tea drinkers can have caffeine sleep problems while believing they avoid caffeine.
Milk makes no difference to the dose. The half-life is the same as coffee's, about 5.7 hours, so an afternoon mug behaves like half an afternoon coffee.
Compared with the rest of the tea
| Drink | Serving | Caffeine |
|---|---|---|
| Yerba mate | 8 oz cup (240 ml) | 84 mg |
| Matcha | 8 oz cup (240 ml) | 67 mg |
| Black tea | 8 oz cup (240 ml) | 48 mg |
| Oolong | 8 oz cup (240 ml) | 38 mg |
| White tea | 8 oz cup (240 ml) | 36 mg |
| Chai latte | 10.1 oz cup (300 ml) | 30 mg |
| Green tea | 8 oz cup (240 ml) | 29 mg |
| Herbal tea | 8 oz cup (240 ml) | 0 mg |
Common questions
How much caffeine is in black tea?
Black tea has about 48 mg of caffeine per 8 oz cup (240 ml). That is 12% of the 400 mg daily limit for a healthy adult, or about 0.5 mugs of filter coffee.
How long does the caffeine in black tea last?
It peaks about 45 minutes after you drink it and halves every 5.7 hours. For an average adult one 8 oz cup takes about 1 and a half hours to fall below 40 mg, the line Cira uses as low enough to sleep on.
How late can I drink black tea and still sleep?
For an 11 pm bedtime the latest is about 9:18 pm. Move it by the same amount as your own bedtime. People who clear caffeine slowly should stop about two hours earlier.
How many servings of black tea can I have in a day?
About 8, going by the 400 mg daily limit for healthy adults. That limit covers everything else with caffeine in it too, so the real number is lower on a day with other coffee, tea or cola.
Read next
Compare and look up
Where these numbers come from
Caffeine content is the typical value for the serving shown, the same figure the Cira app uses. Brands and brew methods vary, so treat it as a good estimate rather than a measurement of your cup. The 5.7 hour half-life is a typical value for healthy adults, the 40 mg sleep line is a working threshold of the model, and the 400 mg daily limit is the figure used by the European Food Safety Authority and the US FDA. How the numbers are worked out.
