nutrition · 1 min read
How much caffeine in a cup of coffee? Brew by brew
A standard 8 oz brewed cup carries 80 to 100 mg of caffeine, an espresso shot about 63 mg. How much caffeine in a cup of coffee really comes down to brew method and cup size.
Written by Lifebar Desk · Checked against the sources listed below
Published 06 Sept 2026
Key takeaways
- An 8 oz brewed coffee averages 80 to 100 mg of caffeine; a single espresso shot is about 63 mg.
- The FDA considers up to 400 mg a day safe for most healthy adults, roughly four brewed cups.
- Large coffee-shop drinks can carry 200 to 400 mg in one cup because of size and shot count.
"A cup of coffee" is one of the least standardised measurements in nutrition. The number on the label and the number in your mug are rarely the same.
The baseline numbers
| Drink | Typical caffeine |
|---|---|
| Brewed coffee, 8 oz | 80 to 100 mg |
| Espresso, 1 shot (1 oz) | ~63 mg |
| Instant coffee, 8 oz | 60 to 80 mg |
| Cold brew, 12 oz | 150 to 240 mg |
| Decaf, 8 oz | 2 to 5 mg |
| Black tea, 8 oz | 40 to 50 mg |
Why your actual cup is usually higher
Two things inflate the real dose. First, a "cup" in the kitchen is 8 oz, but a mug is 12 to 16 oz. Second, coffee shop sizes start at 12 oz and large drinks often carry two or three shots. A 16 oz brewed coffee with an extra shot can land near 300 mg, most of a day's allowance in one drink.
What counts as too much
The FDA's reference point is 400 mg a day for healthy adults, roughly four 8 oz brewed cups. Pregnancy guidance is lower, commonly 200 mg. Sensitivity varies widely because the liver enzyme that clears caffeine differs genetically by a factor of several.
The timing question
With a half-life of five to six hours, caffeine consumed at 4pm still has a quarter of its dose active at 10pm. Trials that dosed caffeine six hours before bed found about an hour of lost sleep, measured on a monitor, even when people reported sleeping fine.
A practical cutoff: nothing caffeinated after early afternoon, and know the size of what you are actually drinking.
Frequently asked
Does dark roast have more caffeine?
Slightly less by volume. Roasting burns off a small amount, so light roast measured by scoop edges out dark, though the difference is minor next to serving size.
How long does caffeine stay in your system?
The half-life averages five to six hours, so a 3pm coffee still leaves roughly half its caffeine circulating at 9pm.
Sources
Educational content, talk to your clinician before changing treatment.
