Is a dark roast coffee stronger than a light roast?
I’ve heard this question and seen it being asked online a lot! It seems to be the general consensus that a dark roast gives you a bigger kick than a light roast. But is that actually true?
It’s an important question. We should keep an eye on how much caffeine we’re consuming. But whether you’re asking because you’re being health conscious, or if you’re trying to win an argument with a mate, we’ll clear up this question once and for all.
However, the answer isn’t a simple yes or no.
- Quick Recap – What Is A Dark Roast?
- Let’s Define What ‘Stronger’ Means
- Is A Dark Roast Stronger Than A Light Roast In Terms Of Caffeine?
- Other Factors That Influence Caffeine Content
- Shall We Talk More About Taste?
- Final Thoughts
Quick Recap – What Is A Dark Roast?
I know some of you that have just landed on this page will already know what a dark roast is. But for those of you that don’t, here’s a quick explanation.
To create coffee beans that make a lovely brew, we need to roast them. Light, medium and dark roast correspond to how long the beans have been roasted for.
Light roast beans have been roasted for a shorter time than a dark roast.
If we’re to get technical, there’s such a thing as ‘first crack’ and ‘second crack’. A ‘crack’ is where the moisture inside the beans starts to evaporate, getting forced to the outside of the bean. This creates such a pressure that the outside of the bean cracks.
A light roast is taken out of the roaster during the first crack. A dark roast is taken out during, or just after the second crack. A medium roast sits somewhere between the end of first crack and the beginning of second crack.
Let’s Define What ‘Stronger’ Means
Saying a coffee is strong can be a little ambiguous. Do we mean the flavours and notes are strong, or that it’s got a strong caffeine kick?
There are quite a few brands out there today that have figured out how to make really high caffeine content coffee.
They can do this by taking a species of coffee called Robusta (Coffea canephora) which has a much higher caffeine content than the world’s favourite, Arabica coffee (Coffea arabica). Both beans make up the blend of coffee, with the majority of beans being Arabica.
There’s enough Robusta beans in the blend to increase the overall caffeine content of the coffee, but not too much that it’s going to bring an unpleasant flavour, as with caffeine comes bitterness.
We can describe coffee as having a really strong taste too. Most of the time this is how dark roasts are described, especially if they’re bordering on being black.
But this could just be because of a lack of words to describe the taste. Often these dark roasts can bring out the deeper, richer and smokier flavours from the bean, where you would be forgiven for describing the coffee as strong.
We’ll come back to taste later on but let’s talk about the relationship between caffeine and roast level.
Is A Dark Roast Stronger Than A Light Roast In Terms Of Caffeine?
Well technically it depends on what your metric is, but the statement that a dark roast coffee contains more caffeine than a light roast isn’t exactly true.
Caffeine Content In Coffee – Explained
Whether you have a single light roast bean or dark roast bean, the caffeine content inside is going to be pretty much the same. In fact, during the roasting process, the amount of caffeine barely changes and remains stable.
As it turns out, when coffee beans are being roasted, they lose water and increase in size slightly, and the longer the roast time is, the more these effects take place. Therefore, dark roast beans will weigh less and be a little larger than light roasts.
Therefore, it all depends on how you measure the beans in the first place, as to which roast has more caffeine.
Measuring By Scoop (Volume)
You walk into a cafe, the barista gives you a big smile and asks what you’d like to order. “An espresso” you say, to which he replies “coming right up!” as he gets to work to brew your coffee.
The barista takes a scoop of light roast coffee, a scoop of dark roast coffee, and places them next to each other. Assuming that both scoops contain exactly the same amount of coffee beans, the light roast scoop will contain more caffeine.
Now hear me out.
Reason being is that each light roast bean is more dense, weighs more, and therefore contains a tiny, little bit more caffeine than the dark roast beans.
In individual beans, it wouldn’t make much of a difference, but when you scale that up to 100g and measure the beans by volume, the difference in caffeine becomes slightly more apparent.
Measuring By Weight
The way to ensure that a cup of light roast coffee, and a cup of dark roast coffee contain the same amount of caffeine, is by measuring the beans by mass.
You’ll need more dark roast beans to make up 100g of ground coffee than you would light roast beans. But once you have the same weight, you should have about the same amount of caffeine in each cup once brewed.
The Bottom Line
Each particle of ground light roast coffee will be more dense and heavier than a dark roast, and therefore contains more caffeine.
So you need to measure out your beans by weight to try and get the same amount of caffeine in each cup. If you measure by volume, the light roast beans will give you more of a caffeine kick.
Other Factors That Influence Caffeine Content
It’s not just the roast or the way we measure our beans that will have an effect of caffeine content. There are many, many different variables. It’s almost impossible to tell how much caffeine is in a single cup unless you go get it sent to a lab. Or unless you follow your coffee bean from crop to cup.
The Species Of Bean
As you most probably know there are two species of coffee bean that are most commonly used. Arabica coffee (Coffea arabica) and Robusta coffee (Coffea canephora).
In most blends you get today, there will be a mix of Robusta and Arabica beans inside the bag. This is because Arabica is regarded as the better quality bean in terms of flavour, and is therefore more expensive, so Robusta beans are used as a filler.
This brings the cost of production down, without doing much to the quality of the brew.
However, Robusta beans have considerably more caffeine in them than Arabica. Robusta sits at a 2.7% caffeine content, whereas Arabica has a 1.5% caffeine content.
So if you’ve got a coffee blend with Robusta and Arabica beans, there’s probably going to be more caffeine in that blend, than if the bag was labelled ‘100% arabica’.
Your Chosen Brew Method
Depending on how you brew your coffee changes the caffeine content.
The recommended daily caffeine dosage is 400mg, but you should try not to consume more than 200mg at any one time.
I’m sure it comes to no surprise that an espresso contains the most caffeine, at around 122-130mg of caffeine per 30ml of coffee.
Shall We Talk More About Taste?
So we’ve covered caffeine. Done and dusted. But let’s talk more about taste.
There are so many different flavours, aromas and textures when it comes to coffee. You’re truly spoilt for choice. There are so many good coffee brands out there now, who really care about coffee and who want you to drink the good, fresh stuff.
But for those of us that are wanting to explore our palette for coffee, then we need to know what to expect with each roast, and each roast is unique with its own flavour.
This two minute video gives a super quick, but informative summary of each roast, and skims over the caffeine content of a dark roast:
Don’t mistake ‘light’ for ‘weak’. A light roast coffee certainly does not mean it lacks flavour, or caffeine, as we have now found out.
A light roast is great for exploring the inherent characteristics of the bean. This can change depending on where the coffee has been grown. Things like soil composition, sunlight, humidity and rainfall can affect the flavour.
Light roasts can be quite sweet, with floral, citrus or berry notes, but there’s a fine line between perfecting a light roast, and ruining it.
Medium roasts take on a little more brown in colour, and are a little more of a balanced cup of coffee. In the US, a medium roast is the most popular, due to the fact it has that traditional cuppa joe that everyone is so familiar with.
They can still retain some of those floral and fruity notes, but with them being in the roaster for a bit longer, the sugars start to break down. This means you can start to taste some deeper flavours hidden in the bean.
This is where you start getting those rich, intense flavours that are associated with a dark roast. You can get a bittersweet aftertaste, which is common with the darker roasts, but not always present.
With the sugars beginning to caramelise, you get some sweet flavours like caramel or chocolate starting to shine through.
With medium and medium-dark roasts, there isn’t as much of a fine line between a great coffee and a mediocre one, unlike a light or dark roast. This means you can get a lot of different flavoured medium roast coffees, as there’s a lot of room to play with and explore.
Dark roasts, being in the roaster for the longest, begin to release oils which move to the outside of the bean. If your bag of dark roast whole bean coffee has an oily surface, that’s normally a sign of a freshly roasted batch.
This roast dominates the flavour of the bean, creating flavours that are smokey, ashy and sometimes quite bitter. There are some dark roasts out there that don’t have a bitter aftertaste, but some people like it.
There are some beautiful dark roasts that have a perfect balance between sweetness and acidity, however it can be difficult to get this roast perfect.
I’d recommend trying a load of different coffees, from different places and different roasts.
From this experience, you’re going to know which roasts hit that sweet spot, and which ones you’ll pass on in future.
Figuring out caffeine content in coffee certainly isn’t a straightforward task. There are lots of variables. It’s something I’d love to investigate further, and probably will further down the road.
But the take home point is that no, a dark roast does not have more caffeine than a light roast. It all depends on how you measure your beans.
To get the same amount of caffeine in each cup regardless of the roast, you’re going to want to weigh your beans, instead of scooping or counting your beans.
Make sure you check out some of our coffee bean reviews so you know you’re getting some quality coffee.