Since I’m on the topic of caffeine, I might as well address a question that plagues coffee drinkers and causes arguments among coffee newbies. It’s been confusing over the years, so let’s put it to bed: What coffee has the most caffeine? How much caffeine do different forms of coffee have? How can espresso have more caffeine than coffee?

Through pressure, surface area, and temperature, espresso has more caffeine per ounce than coffee because it can extract it more efficiently. More interestingly, it’s difficult to tell the caffeine content of any given drink.

For that last sentence, I’ll expand.

Can we trust the stated caffeine content?

I thought this article would be easy. Just look up the content of caffeine and compare them, right?

Apparently, it’s significantly trickier.

This study bought the same 16oz Breakfast Blend from the same Starbucks location on 6 consecutive days, then analyzed the caffeine content. 

They found that caffeine ranged from 259-564mg per cup. That’s 16-35mg per ounce – meaning you could get twice as much caffeine as the day before – from the same location. And I’d bet my left arm that Starbucks has rigid, automated approaches to making their drip coffee. It seems like it must be the beans, themselves, that vary.

Authoritative sources seem, at best, to be guess-working with lackadaisical rigor. There is no authority that seems to be pushing for accurate data on this, so it seems each industry is just doing whatever they please. Citation needed.

Bottom line: Not really. 

At some point, I had to stop doing research and just take the best sources I could find. Assume that each number can vary from 0.5-2x the value listed. Fun!

I used a table from an academic source that scoured several official channels and came up with their own numbers.

In case you’re wondering why I trusted them, here’s what they said about their sources:

Caffeine values were obtained from several resources… [including] the USDA Food and Nutrient Database for Dietary Studies, the USDA National Nutrient Database for Standard Reference, Release 24 (US Department of Agriculture and Agricultural Research Service, 2011), and the Nutrition Data System for Research (Nutrition Coordinating Center, 2011).

Mitchell et al. (2015)

It just seemed more comprehensive than most blogs (flimsy or no sources at all) or even Mayo Clinic (had sources but didn’t actually reference them in the article… at all. What’s the point of listing them?)

Is Espresso Stronger than Coffee?

In this question, there are a few assumptions I’m going to lay out first: “stronger” will be measured in caffeine content, and “coffee” will be considered “drip coffee”.

It’s difficult to get solid numbers, as most websites don’t source anything with links. One said that the US Agriculture Dept (no link) said 1 fl oz of espresso has 63.6 (that 0.6 is totally significant (not!)), while another stated that Starbucks has 75mg in their shots of espresso.

It’s probably not significant enough to go down to decimal places, as different strains, crops, regions of coffee have varying amounts. For example, robusta tends to have over 2x the caffeine content of arabica, and they’re often used in espresso mixes because robusta produces nicer crema. If they use different amounts of robusta, the shots will swing up or down in caffeine content.

The generally agreed amounts seem to be:

• Espresso (1 fl oz) has around 65mg
• Drip coffee (8 fl oz) has around 95mg

But again, due to various factors, just remember that those can range from 50%-200% of the listed value. Fun!

For a more comprehensive list, I have academic sources and tables below.

Which has more caffeine, Light or Dark Roasts?

As Kicking Horse coffee (one of my preferred brands, check out their “Three Sisters”) points out in this post: dark roast and light roast have approximately the same amount of caffeine, but it depends how you measure.

Dark roast expands due to the creation and release of steam during the roasting process. Thus, the dark roast beans are less dense. If you measure by volume, there will be fewer beans in each scoop, validating the theory that light roasts have more caffeine.

This is why most serious coffee people use weight (grams), not volume (scoops/tbsp). If you measure by weight, the difference is negligible.

Lesson: Buy what you like the taste of.

How the Chemistry Works

The ability to extract caffeine from coffee is affected by several factors. In the past, I was confused as to how espresso could possibly have more caffeine than drip. It needs more time! I thought. There’s no way a 30-second espresso pull can compare!

But that’s wrong. And here’s why:

“Extraction” is affected by several things, including:

• Surface Area: powdered coffee has the highest surface area available, allowing the water to absorb more solutes (like caffeine) at a faster rate. Imagine burning wood chips versus burning a giant log. The log will take much longer to burn because of the lower surface area.
• Pressure: chemical processes are affected by pressurization, often being sped up by increasing it. As an example, pressure cookers are 30% faster than conventional methods of cooking. Espresso is under 9-15 bars of pressure (9-15x atmospheric pressure at sea level), while most other forms of coffee don’t apply any additional pressure.
• Temperature: cold brew takes longer for this reason. Hotter means faster.
• Time: Even though cold brew takes a lot longer, it can be stronger than the average drip coffee because it has been given 12+ hours to brew.

This is a long way to say that espresso has more caffeine concentration than most beverages because of how it’s made, despite the short time: high surface area, high pressure, high temperature.

Below is a table that shows the difference between cold brew and hot brew caffeine content. Before you read this and say that it is evidence of different roasts and caffeine content, remember that the study is primarily looking at the brew methods – not the caffeine content of roasts. This study only looked at one sample of each roast. To know how roasts actually vary, you’d need a lot more of each kind, use the same brew method, and then average the amounts.

In either case, it’s interesting how brew methods affect caffeine content!

Chart

Once more, I will state that the values here are averaged and probably vary between 0.5-2x of what is stated here. 

I’m pulling most of the data from this study, particularly the right column of the table, because it is composed of wide samples that have been averaged. 

The left column, if you’re curious, covers the average of what brands claim to have. I find the broad samples of real-world products to be more accurate and trustworthy than what a brand says about itself.

Coffee	Mg/fluid ounce
Regular, brewed, non-specialty, including K cups and other single-serve varieties	11.9
Regular, instant, brand or no brand specified	9.4
Prepared from flavored mix, all varieties	6
Specialty coffees, all	11.9
Cappuccino	15.8
Mocha or other flavored [with] syrup	10.6
Cafe au lait or latte	11.9
Specialty coffee, espresso	62.8
Ready to drink, bottled or canned	9.4
Decaf (all types)	0.25
*Turkish Coffee (not from the referenced study) (source; not credible)	20-30 (source stated 40-60mg / 2 fl oz)
*French Press (Not from the referenced study) (source; not credible)	13.5

If you want to compare some of those numbers, Starbucks tall espresso beverages get 1 oz of espresso; grande gets 2 oz; venti can get 2 or 3 depending on the beverage. Apparently, iced ventis can get 3 oz.

Extra

The same study that went to Starbucks 6 days in a row also bought 20 caffeinated beverages and measured their caffeine content. 

It’s not super useful because the amount changes so much from cup to cup, but at least we can see a general smattering of caffeine values from the examined drinks:

Coffee and Origin	Amount	Caffeine Dose (mg)
Big Bean Espresso, 1-shot	1 shot	75.8
Big Bean Espresso, 2 short shots	2 short shots	140.4
Big Bean Espresso, 2 tall shots	2 tall shots	165.3
Starbucks Espresso, regular, small	1 shot	58.1
Hampden Café Espresso	2 shots	133.5
Einstein Bros® Espresso, double	2 shots	185.0
Brewed Specialty Coffees
Big Bean, regular	16 oz	164.7
Big Bean Boat Builders Blend, regular	16 oz	147.6
Big Bean Organic Peru Andes Gold, regular, country origin, Peru	16 oz	186.0
Big Bean French Roast, regular	16 oz	179.8
Big Bean Ethiopian Harrar, regular, country origin, Ethiopia	16 oz	157.1
Big Bean Italian Roast, regular, country origin, Brazil	16 oz	171.8
Big Bean Costa Rican French Roast, regular, country origin, Costa Rica	16 oz	245.1
Big Bean Kenya AA, regular, country origin, Kenya	16 oz	204.9
Big Bean Sumatra Mandheling, regular, country origin, Indonesia	16 oz	168.5
Hampden Café Guatemala Antigua	16 oz	172.7
Starbucks regular	16 oz	259.3
Royal Farms regular	16 oz	225.7
Dunkin’ Donuts regular	16 oz	143.4
Einstein Bros regular	16 oz	206.3

TL;DR

It’s hard to say how much caffeine anything has, though it seems there are ranges. If you want to look up the officially stated caffeine amounts, then you can use this website as a tool, but all values should be taken as the center point of a range. 

If they say 50mg, it could be 25mg or over 100mg. It seems the average beverage, even if in strictly controlled settings, still have large variation in the caffeine content.

But if you’re wondering whether espresso is stronger (per ounce) than other forms of coffee, the answer is yes, and appears to have an even higher concentration than Turkish coffee.