How Much Caffeine Is in Coffee?

Caffeine content is probably the most common question people ask about coffee, and the honest answer is a range, not a single number. Two cups of coffee made in the same kitchen can differ substantially depending on how much coffee went in, how it was brewed, and — most of all — how big the cup is.

This article lays out the typical numbers, where they come from, and what actually moves them.

Typical caffeine by drink

Figures are drawn from USDA FoodData Central^[1] and FDA consumer guidance^[2]. Cold brew is listed without a number on purpose: concentrations and serving sizes vary so much between products that a single figure would be misleading. It is often higher per serving than drip coffee simply because servings are larger and the coffee-to-water ratio is stronger.

Milk-based espresso drinks — lattes, cappuccinos, flat whites — carry the caffeine of their espresso shots. The milk changes the volume and taste, not the caffeine. A double-shot latte lands around 120–130 mg regardless of how large the cup is.

Caffeine by brew method, in more detail

The category-level table above hides variation between brewing styles. Different methods extract at different rates and use different coffee-to-water ratios, which changes the number in the cup.

Moka pot and French press land in the same range as filter drip because their higher extraction pressure or longer contact time roughly cancels out temperature differences. AeroPress varies by recipe — a long "inverted" steep pulls more caffeine than a quick press. Turkish coffee looks intense but its small serving size keeps total caffeine moderate.

Cold brew is the outlier. Long 12–24 hour steeps extract caffeine efficiently despite the low temperature, and typical concentrate ratios are much stronger than hot brewing — often 1:4 to 1:8 by weight versus about 1:16 for drip^[8]. The result is a high caffeine load per ounce of concentrate, though most people dilute it before drinking.

Caffeine in decaf: how much really remains

Decaffeination removes most but not all of the caffeine from a coffee bean. The FDA describes an 8 oz cup of decaf as containing roughly 2–15 mg^[2], but the number is not uniform across brands. A 2006 laboratory analysis of retail decaf coffees found that 16 oz servings from major coffeehouse chains contained anywhere from about 8 mg up to 32 mg of caffeine per serving, with substantial brand-to-brand and even shop-to-shop variation^[7]. Brewed decaf prepared at home from decaffeinated whole beans tends to sit at the lower end of that range; espresso-based decaf drinks can sit noticeably higher because of the concentrated shot.

For most healthy adults this is background noise. For people who are strictly limiting intake — pregnancy, certain cardiac conditions, severe caffeine sensitivity — a few cups of decaf can add up to a meaningful dose, and choosing a home-brewed decaf over a large espresso-based one from a café is a practical way to keep exposure low.

Why the numbers vary so much

Serving size is the biggest factor

A "cup" of coffee is a slippery unit. Nutrition references typically use 8 oz (240 mL), but many home mugs hold 12–16 oz, and large café sizes can exceed 20 oz. A 16 oz mug of the same drip coffee is simply two reference cups — roughly 190 mg rather than 95 mg. Before comparing your intake against any guideline, check what your actual cup holds.

Bean species: arabica vs robusta

Robusta beans contain roughly twice the caffeine of arabica by weight^[6]. Most specialty coffee is arabica, while robusta is common in some instant coffees and traditional espresso blends. If a blend includes robusta, its brewed caffeine will run higher than the arabica-based figures above.

Roast level matters less than people think

Caffeine is relatively heat-stable, so light and dark roasts contain similar caffeine per bean^[6]. The differences people attribute to roast usually come from measurement: dark-roasted beans are less dense, so a scoop of dark roast contains slightly less coffee by weight than the same scoop of light roast. Measured by weight, the difference largely disappears.

Why the same cup varies day-to-day

Even from the same beans on the same equipment, caffeine per cup shifts from brew to brew. The main levers are dose (a heaped scoop is a 10%-plus swing on a 15 g brew), grind size (finer grinds extract more in the same contact time, especially in espresso^[9]), and water temperature and contact time. Cup-to-cup variability in commercial espresso is well documented, with substantial shot-to-shot caffeine variation reported even at supposedly standardised café settings driven by dose, tamp, and grinder consistency^[10]. If a cup feels unusually strong or weak, something in the process has almost certainly shifted.

Brew method and ratio

More coffee per unit of water, finer grinds, and longer contact time all extract more caffeine into the cup. This is why cold brew concentrates and espresso are strong per ounce, and why the same beans can produce noticeably different cups across methods. Brew strength and total caffeine are related but not the same thing — a bitter cup is not necessarily a high-caffeine cup.

How long caffeine stays in your system

Caffeine's half-life — the time for your body to clear half of a dose — is commonly cited in the range of about four to six hours in healthy adults, though it varies considerably from person to person^[5]. In practice, that means a mid-afternoon coffee can still leave a meaningful fraction of its caffeine in your system at bedtime, which is worth knowing if sleep is a concern.

Coffee culture, coffee dose: an international snapshot

The same drink name can hide very different caffeine loads across countries. A traditional Italian espresso is a short 25 mL shot at 60–80 mg, drunk in a couple of sips. An Australian long black — an espresso shot poured over hot water, typically a double — lands at around 120–150 mg per serving. American drip scales with size: a 12 oz US chain "small" sits around 140–170 mg, a 20 oz around 300 mg. Turkish and Greek coffee look intense but are small servings, around 50–80 mg. Vietnamese phin drip uses robusta beans, which have roughly twice the caffeine of arabica by weight^[6], and a small phin serving can hit 130–200 mg.

If you drink coffee while travelling, size and brew method — not the national label — do most of the work of predicting the dose.

Caffeine guidance for kids and teens

Adult guidance does not scale down neatly for younger drinkers. Health Canada publishes specific caffeine limits by age: no more than 45 mg per day for children aged 4–6, 62.5 mg for ages 7–9, 85 mg for ages 10–12, and — for adolescents 13 and older — no more than 2.5 mg per kilogram of body weight per day^[3]. That works out to roughly 100–175 mg per day for a typical teenager, depending on body size.

A single 8 oz cup of drip coffee at 95 mg is already at or above the daily ceiling for a child under 10, and close to the daily maximum for a 13-year-old. Chocolate, tea, cola, and energy drinks all contribute to the same daily total. Pregnancy guidance sits lower still: a maximum of 300 mg per day in Canada, with some obstetric groups suggesting closer to 200 mg, and applies during breastfeeding as well^[3].

How to estimate your own cup

1. Start with serving size. Measure what your mug actually holds; it is probably not 8 oz.
2. Count espresso shots. Each shot contributes roughly 60–65 mg, whatever the drink is called.
3. Use ~12 mg per fluid ounce as a rule of thumb for brewed drip coffee, based on USDA averages^[1].
4. Check the label for instant and packaged drinks. Products vary, and the label beats any generic table.