How much caffeine is in black tea?

An 8 fl oz cup of black tea has 47 mg of caffeine.

That's about half a cup of brewed coffee, and 12% of the 400 mg a day the FDA cites for most healthy adults.

Source: USDA FoodData Central · checked 10 Nov 2026

When did you have it?

Had at 3 pm, about 17 mg is still in you at an 11 pm bedtime. That should not affect most people’s sleep.

Bedtime

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Latest time to drink it

For an 11 pm bedtime, an 8 fl oz cup of black tea stays under the 50 mg most people sleep fine with, even late in the evening. The table works it out for other bedtimes and for how sensitive you are: it is the latest time to start one so that the caffeine left stays under the line all night.

Bedtime	Very sensitive under 25 mg	Average under 50 mg	Not very sensitive under 100 mg
9 pm	3:55 pm	Any time	Any time
10 pm	4:55 pm	Any time	Any time
11 pm	5:55 pm	Any time	Any time
Midnight	6:55 pm	Any time	Any time
1 am	7:55 pm	Any time	Any time

For an 8 fl oz cup of black tea, average clearance (half-life 5 h), 8 hours of sleep. "Any time" means even one at bedtime stays under the line.

How long it lasts

The caffeine from an 8 fl oz cup of black tea peaks in your blood about 75 minutes after you start it, at roughly 40 mg. Half of it is gone in about 5 hours for an average adult; that ranges from roughly 3 to 7 hours, and longer in pregnancy or with some medicines.

Time after	3 hours	6 hours	9 hours	12 hours
Still in you	33 mg	22 mg	14 mg	9.5 mg

So one had at 3 pm leaves about 17 mg at 11 pm. How long caffeine lasts explains the curve.

How it compares

Black tea is stronger than 73% of the 38 teas we track, by caffeine per serving.

Per fluid ounce (5.9 mg) it is stronger than 75% of them.

To reach 400 mg in a day you would need about 8½ of these.

Less caffeine

Dona Masala Chai Concentrate 45 mg, 1 serving
Yorkshire Gold 43 mg, 200 ml mug, brewed 5 min
Kombucha 41 mg, 12 fl oz bottle

More caffeine

Matcha 48 mg, 1 bowl, ITO EN
Yorkshire Tea 48 mg, 200 ml mug, brewed 5 min
Gold Peak Unsweetened Black Tea 50 mg, 18.5 fl oz bottle

FAQ

Is black tea high in caffeine?

It is moderate. An 8 fl oz cup of black tea has 47 mg, which is 49% of the 95 mg in an 8 fl oz cup of brewed coffee.

Can I drink black tea at night?

For most people, yes: even late in the evening an 8 fl oz cup of black tea stays under 50 mg at an 11 pm bedtime.

How long does the caffeine in black tea last?

It peaks about 75 minutes after you start it. Of the 47 mg, about 22 mg is still in you 6 hours later and 9.5 mg after 12 hours, for an average adult with a 5-hour half-life.

Is there a decaf or lower-caffeine version of black tea?

Yes. Decaf Tea has 4 to 6 mg in 8 fl oz cup, 89% less.

Does black tea have more caffeine than a cup of coffee?

No. An 8 fl oz cup of black tea has 47 mg; an 8 fl oz cup of coffee has 95 mg.

Method and limits

The caffeine figure comes from USDA FoodData Central; recipes, brewing and batches vary, so a real serving can differ. The curves use a standard one-compartment model with an average 5-hour half-life and a sleep-friendly line of 50 mg; your own body may clear caffeine faster or slower. How it works has the details.

These are estimates for information, not medical advice.