A standard 1 oz shot of espresso carries about 63 mg of caffeine. Real shots range from roughly 47 to 75 mg depending on the bean, the dose and the grind.
Related conversions
Doubling up gives about 126 mg, and two separate shots comes to the same figure. Three shots reach 189 mg and six reach 378 mg. For the daily ceiling, see how many espressos per day. More under coffee answers.
The number
| Shots | Standard espresso | Starbucks strength | Share of the 400 mg daily cap |
|---|---|---|---|
| 1 shot | 63 mg | 75 mg | 16% |
| 2 shots | 126 mg | 150 mg | 32% |
| 3 shots | 189 mg | 225 mg | 47% |
| 4 shots | 252 mg | 300 mg | 63% |
| 5 shots | 315 mg | 375 mg | 79% |
| 6 shots | 378 mg | 450 mg | 94% |
The standard column uses 63 mg per 1 oz shot pulled from 7 to 9 g of grounds. Starbucks pulls a larger, longer shot at roughly 75 mg.
The last column is measured against the 400 mg per day the FDA describes as not generally associated with negative effects for healthy adults.
Why this is a range, not a constant. Caffeine extraction depends on the bean, the dose, the grind and the length of the pull. Robusta carries roughly twice the caffeine of arabica by weight.
A ristretto pulled short from the same dose lands lower; a lungo pulled long lands higher. Treat every figure here as a planning number accurate to within about fifteen percent, not a laboratory result.
Why a shot is weaker than a mug
Espresso is the most concentrated way to drink coffee and one of the weakest servings by total caffeine. Concentration and dose are different things.
A shot is 1 oz of very strong liquid pulled from 7 to 9 g of grounds; a 12 oz mug of drip is a weaker liquid pulled from 15 to 20 g. More grounds and more water mean more caffeine in the cup, even though each mouthful is milder.
This is why the espresso drinker who switches to filter coffee in the afternoon often sleeps worse, not better.
How it compares
| Drink | Caffeine |
|---|---|
| Single espresso, 1 oz | 63 mg |
| Double espresso, 2 oz | 126 mg |
| Drip coffee, 12 oz | about 140 mg |
| Instant coffee, 8 oz | about 60 mg |
| Black tea, 8 oz | about 47 mg |
| Cola, 12 oz | about 34 mg |
| Energy drink, 8 oz | about 80 mg |
The surprise for most people is the drip row. A single espresso is a concentrated shot, but a mug of filter coffee is a far larger volume — and it wins on total caffeine nearly every time.
What actually changes the number
| Variable | Effect on a shot |
|---|---|
| Robusta in the blend | Up sharply — roughly twice the caffeine of arabica by weight |
| Double basket, 18 g dose | Roughly doubles it — what many bars call a “single” |
| Ristretto, short pull | Down 10 to 20 percent |
| Lungo, long pull | Up 10 to 20 percent |
| Dark roast | Slightly down by weight — roasting burns off a little caffeine |
| Decaf | Not zero: about 3 to 8 mg per shot |
The largest source of confusion is the word “shot” itself. In Italy a single is 7 g and 1 oz. In most speciality bars elsewhere the default basket is 18 g, so what you are handed as a “single espresso” is closer to two Italian shots.
When you drink it matters as much as how much
Caffeine has a half-life of roughly five to six hours in a healthy adult, meaning half of what you drink at 4pm is still circulating at 10pm.
That is the mechanism behind the common complaint that “caffeine does not affect me, but I sleep badly” — tolerance builds against the alertness effect far faster than against the sleep disruption.
Genetics play a large part too. Variation in the CYP1A2 enzyme means some people clear caffeine in half the time others take, which is why a shared cut-off time is useless advice and a personal one is worth finding.
Common questions
Is espresso stronger than coffee?
Per millilitre, yes, by a wide margin. Per serving, no — a 63 mg shot loses to a 140 mg mug of drip.
Does a darker roast mean more caffeine?
No, slightly less by weight. The association comes from taste: darker roasts taste more intense, and people read intensity as strength.
How many shots is safe in a day?
The FDA’s 400 mg guideline works out to about six standard shots. See how many espressos per day for the detail, including why the honest answer depends on the person.
Sources
- U.S. Food and Drug Administration — Spilling the Beans: How Much Caffeine is Too Much? (the 400 mg per day figure for healthy adults)
- U.S. Department of Agriculture — FoodData Central (caffeine content of brewed espresso and coffee)
Figures on this page are planning numbers, not measurements of your particular drink. Caffeine per shot varies with the bean, the dose, the grind and the length of the pull.
