How Much Caffeine Is in a Cup of Coffee? (By Drink and Brew Method)

An 8 oz (237 ml) cup of brewed coffee contains about 96 mg of caffeine, according to the Mayo Clinic. A single shot of espresso has about 63 mg. Those are averages; a real cup can easily land anywhere from about 70 mg to well over 140 mg depending on the beans, how much coffee you use, and how it’s brewed.

Here’s how the common drinks compare, why the numbers move so much, and how to work out what’s in your cup.

Caffeine by drink

Source: Mayo Clinic caffeine chart. Double-shot value calculated from the single-shot figure.

Add up your own day in the caffeine calculator.

Why “a cup of coffee” varies so much

1. The amount of coffee you use

This matters most. Caffeine is very soluble, so a brew captures most of the caffeine in the grounds. Double the grounds and you roughly double the caffeine. A cup brewed at a strong 1:13 ratio can carry noticeably more caffeine than the same size cup at a weak 1:18.

2. Arabica or robusta

Robusta beans contain roughly twice the caffeine of arabica. Most specialty coffee is 100% arabica; many supermarket blends, instant coffees and traditional Italian espresso blends include robusta. If your bag doesn’t say “100% arabica,” assume it might contain some.

3. Cup size

“A cup” on a coffee maker’s carafe is often just 5 or 6 fl oz, while a typical mug holds 10–12 fl oz and a large café coffee is 16–20 fl oz. Drinking one “cup” from a 12 oz mug means about 1.5 times the caffeine of the standard 8 oz serving.

4. Brew method

Brew method matters less than people think, once you account for how much coffee goes in:

• Espresso is the most concentrated per ounce, but a single shot is small, so it has less caffeine per drink than a mug of drip coffee. (More on espresso vs. coffee.)
• Cold brew is usually made as a strong concentrate. Undiluted it’s very high in caffeine; diluted to normal strength it’s similar to hot coffee. (Cold brew vs. iced coffee.)
• French press and pour over sit in the same range as drip when made with similar ratios.

5. Roast level

Dark roast doesn’t have meaningfully less caffeine by weight — roasting destroys very little caffeine. But dark beans are lighter and puffier, so a scoop of dark roast weighs less than a scoop of light roast. Measure with scoops and the dark roast cup ends up with slightly less caffeine; measure by weight and they’re about the same.

Estimate the caffeine in your own coffee

If you weigh your coffee, you can estimate its caffeine directly. Roasted arabica contains roughly 10–14 mg of caffeine per gram of coffee (robusta about 18–24 mg), and most of it ends up in the cup.

Example: a pour over made with 15 g of arabica lands somewhere around 110–210 mg, with a midpoint around 160 mg — already well above the “96 mg” average for an 8 oz cup. That’s because the average comes from typical brewed coffee, which is often made weaker than a carefully measured home recipe.

The caffeine calculator’s “Caffeine in my brew” mode does this math for you. Treat the result as a range, not a lab value.

How much caffeine is too much?

• Healthy adults: the U.S. Food and Drug Administration says up to 400 mg a day is not generally associated with negative effects. The FDA describes that as roughly two to three 12 oz cups of coffee.
• In one sitting: the European Food Safety Authority (EFSA) concluded that single doses up to about 200 mg — around 3 mg per kilogram of body weight — don’t raise safety concerns for healthy adults.
• During pregnancy: the American College of Obstetricians and Gynecologists advises keeping caffeine under 200 mg a day; EFSA uses the same figure.
• Children and teens: there’s no established safe level for kids in the U.S.; pediatric guidance generally discourages caffeine for children.

People vary a lot in how they process caffeine. Some medications, heart conditions, anxiety and sleep problems are reasons to talk with a doctor about a lower limit. If coffee leaves you jittery, anxious or awake at night, that’s your limit, whatever the number says.

Watch the big café cups

The 400 mg guideline sounds like a lot until you look at café sizes. A large (16–20 oz) drip coffee from a coffee chain can contain over 300 mg on its own, because it’s both bigger and often brewed stronger than the 8 oz average. If you buy coffee out, check the chain’s published nutrition information.

Ways to cut back without giving up coffee

• Go half-caf: mix regular and decaf beans 50/50 in your grinder.
• Use a smaller mug or a weaker ratio (1:17 instead of 1:15) for your second cup.
• Switch the afternoon cup to decaf — caffeine’s effects can last many hours, which is why a 3 p.m. coffee can still affect your sleep.
• Choose a single shot in milk drinks instead of a double.

Quick answers

• Brewed coffee, 8 oz: ~96 mg
• Espresso, 1 shot: ~63 mg
• Decaf, 8 oz: ~2 mg
• Daily guideline for healthy adults: up to 400 mg (FDA)
• Pregnancy: under 200 mg a day (ACOG)

This guide is for general information and isn’t medical advice.