From the Coffee Roast to the Type of Coffee Bean: Everything You Know About What Coffee Has The Most Caffeine Is Wrong

But the actual facts according to researchers paint a much more complex picture. And the truth is there are so many variables across at least four primary factors when determining caffeine content, every cup and coffee shop is different.

The U.S. Food and Drug Administration says a healthy adult should cap their intake at 400 mg of caffeine per day. I’m not a doctor, but I do know that high caffeine content contributes to making certain conditions worse.

So if you love coffee and drink it every day like many people, it’s a smart move to know how much caffeine is in your favorite drink.

Ready to get jittery with it? Here’s what the science says.

My Process Researching Which Coffee Has the Most Caffeine

Spoiler alert: Determining what coffee has the most caffeine so you can follow those USDA guidelines is not a simple or straightforward process.

Why? Because of the many variables at play.

That’s why I spent a week going through several academic research papers and recent studies. I took a magnifying glass to myths and let me tell you:

The coffee drinkers I asked in researching this article believe dark roast makes the most caffeinated coffee. They also said espresso has the highest amounts, period.

And that is where common knowledge seems to end.

This is problematic because there are crucial elements that determine if a dark or light roast has more caffeine, a shot of espresso or cold brew, etc.

So I set out on a mission:

• Corral the research.
• Create a definitive article detailing the complexities of caffeine in coffee
• Explain it as simply as possible.

To start, four main factors affect the strength of caffeine levels:

1. Bean type
2. Roast level
3. Grind size
4. Brewing type

Each of these factors has significant nuances we have to examine when determining the most caffeinated cup of coffee.

We need to go through each of them to get to the truth, rather than conveniently overlook complexity in favor of a quick answer.

Here’s why:

It’s not just the individual factors. It’s how you combine them for any one cup of coffee that finally determines the highest amount of caffeine.

Arabica Coffee vs. Robusta: What Type of Coffee Beans Have the Most Caffeine?

The short answer: Robusta!

But different types of coffee beans have different levels. In fact, Robusta has nearly twice the amount of caffeine as the Arabica coffee bean.

According to the National Library of Medicine: “Arabica green beans contain, on average, 0.9 to 1.5% dry weight of caffeine. In contrast, Robusta green beans have between 1.2 and 2.4%.”

Remember: This is an average.

The coffee’s origin affects caffeine levels, too.

One study tested caffeine differences between Arabica and Robusta green coffee beans solely grown in India.

In the case of the study on Indian coffee, researchers isolated the caffeine in equal amounts of 100 grams across two samples.

They found their Robusta beans sample to contain 182 mg of caffeine per 100 g. The Arabica sample yielded 154 mg/100 g.

The conclusion is that Robusta beans still contain more caffeine than Arabica across origins. But not exactly ‘double’ the amount everywhere.

Yet you’d be hard-pressed to find a light Robusta-only blend.

Light Robusta on its own is not popular (or easy to find) because of its savory, grainy, and even vegetal flavor.

Not palatable to most people, but does make coffee with an extra kick.

That’s why roasted Robusta coffee beans are either medium-to-dark on their own. Or, roasters add it in small quantities to Arabica light roasts to increase the caffeine per volume.

What Coffee Roast Has the Most Caffeine Content?

The short answer is: If measured by weight, dark roasts have more caffeine. If measured by volume, like with a spoon, then lighter roasts have more caffeine.

Let me explain why.

You see, there is a common misconception that roasting dramatically changes the caffeine content in beans.

This simply isn’t true. Whatever caffeine is in the green coffee bean is also in the roasted bean, and any attributed differences in caffeine content will be slight.

Roast Level and Weight Both Impact How Caffeinated Coffees Are

The longer you roast coffee, the more porous the bean becomes, making darker roasts lighter in weight. So, the darker the roast, the less the beans weigh, but the bigger they are.

This means if you weigh your coffee, a dark roast cup’s caffeine has more of the compound since you need more beans to account for weight.

Say your grind size is the same between a light and a dark roasted batch of beans. One gram of the dark roast will hold more caffeine because dark beans weigh less.

If you are not weighing your coffee after grinding it, the situation is completely different.

Lighter roasted beans are technically smaller and have more mass or density. So, more coffee fits into volumetric measurements—like a tablespoon.

If you just scoop ground beans into your French press, for example, you’ll have more caffeine per bean with light roast rather than dark roasted beans.

All this said, there is likely to be a negligible difference in caffeine content from the roast. Where we really get the most caffeine variances is with the beans.

Does Grind Size Affect Coffee Caffeine?

Yes, significantly.

If your bean and roast type influence total caffeine mass (potential punk rock band name?), think about grind size as available surface area.

The finer the grind, the more coffee becomes available to water during extraction. And because caffeine is one compound out of several in coffee, it dissolves early on in the brewing process. With Turkish coffee, for instance, the grind size is close to a super fine powder. 

So when you brew finely ground coffee, you’re increasing the ratio of coffee to water.

Different brewing methods call for different grind sizes. But generally speaking, a finer grind yields more caffeine, faster.

What Type of Coffee Brewing Method Brews the Strongest Coffee Beverage?

If you’ve gotten this far, you may be wondering which coffee has the most caffeine per cup.

Espresso has the highest caffeine by concentration. And espresso has the most caffeine when extracted by machine. But cold brew has an espresso drink beat by volume, according to this Italian study.

Here’s a graphical abstract from the study detailing its comparisons across eight brewing methods:

How you brew your coffee dramatically affects how much caffeine you extract into your java.

In fact, your chosen brewing method is a much clearer indicator of how much caffeine you’re drinking than roast or bean type.

Comparing Espresso vs Cold Brew

Espresso extraction’s pressure through fine grounds yields hyper-concentrated coffee. But you are likely not drinking 10, 12, or 16 oz. of espresso. You drink more brewed drip and cold brew coffee.

So again, we have to consider the most caffeine-derivative brewing method in two ways: Concentration vs. volume.

• By concentration, espresso undoubtedly wins at 63 mg of caffeine per ounce (or one shot).
• By volume, cold-brewing coffee wins at about 200 mg of caffeine per 16 ounces.

Espresso vs Cold Brew vs Hot Drip Coffee: Which Has the Highest Caffeine Content?

Technically: Espresso, again by concentration at 63 mg per shot. But hot drip coffee has cold brew beat by volume on this one.

Why?

The cold brew extraction process calls for more ground coffee than hot brewed java, so the method itself yields higher levels of caffeine.

In fact, cold brew’s coffee-to-water ratio is about 2.5 times higher than hot drip java.

Yet, if you equalize cold brew’s coffee-to-water ratio to that of hot brew, the latter wins hands-down.

This is because hot water extracts more caffeine from coffee than cold water. In fact, hot-brewed coffee contains between 12-16 mg per ounce or 192-256 mg per 16 ounces.

The other factors we’ve discussed that determine what caffeine amounts still affect whether cold brew or hot brew is stronger. You need to consider your bean and roast types, serving size, and grind size, too.

But typically, with the coffee-to-water-ratio equal, our champs are:

• Espresso has more caffeine per concentration.
• Hot-brewed drip coffee has the highest amount per volume.

What to Add to Coffee for Energy if You’re Looking for Less Caffeine?

OK, so let’s say you’ve read this article and are wondering how you can feel more energetic from drinking coffee. But you don’t want to increase your amount of caffeine per day.

Although the guidelines I’ve detailed have caffeine coffee ranges, you might know how much caffeine you’re drinking already and be looking to actually cut back. Or, you’re sensitive to it and want to experiment with healthy additions or supplements.

I’m all for that personally, so I thought I’d share some things I’ve tried when I want a boost but know another coffee would send me spinning.

So, if you want an extra eye-opener out of your coffee without adding more caffeine, try adding a bit of:

• Cinnamon
• Cardamom
• Cayenne powder
• Coconut or MCT oil
• Unsweetened cacao powder

Not all at the same time, of course. 😉

Each of the above provides a slew of antioxidants and energy-boosting nutrients that you can hide in your coffee.

That said, I am definitely not a doctor, so talk to yours before supplementing your morning coffee using any of these ingredients.

The Cliff Notes – From Light Roast and the Type of Bean to Most Caffeinated Coffee Drinks: What’s the Coffee with the Most Caffeine?

To wrap things up, caffeine concentration is dependent on any combination of these four factors:

1. Light or dark roast does not matter as much as how you’re measuring out coffee: By weight or volume (spooning it out of the bag). Dark roast yields more caffeine when weighed. Light roasted coffee beans contain more by volume. The opposite is also true: Darker roasts have less caffeine by volume. Light roast brewed coffee has less by weight.
2. Robusta beans generally contain about twice as much caffeine as Arabica, but the actual number varies by the coffee bean’s origin. Different types of coffee farm environments (like altitude, climate, and soil) significantly affect how much caffeine is in your coffee.
3. The finer the grind, the higher you’ll be flying. More surface area means you can extract more caffeine from the coffee.
4. The brewing method is an influential factor in how much caffeine ends up in your cup. Machine-brewed espresso has the highest amount of caffeine per concentration. But cold brewing wins out on volume because of the sky-high coffee-to-water ratio.

Phew! That’s it for this one, coffee lovers. Looking into this topic is like opening a can of worms in some respects. You think it’ll be straightforward until you realize how complex the bean-to-cup adventure is!

So while I can’t provide simplicity, I do hope this has made sense and been helpful.

Strong Coffee Calculator: Discover How Much Caffeine is in Your Cup

I used the ranges from the research I found to put together a calculator that estimates how highly caffeinated coffee will be by combining the factors discussed above. Remember: This is an estimate only.

What’s the Most High-Caffeine Coffee? – FAQs