The main difference coffee drinkers notice when comparing light and dark roasts of coffee is the flavor. Even when made from the same bean, a lightly-roasted coffee tastes completely different than a darkly-roasted coffee.
While the taste may be the most important and most notable difference between dark and light roasts, though, it’s not the only difference between the two. A lot of changes take place in a coffee bean during the roasting process, and these changes affect the roast’s look, flavor, acidity, caffeine levels, and more.
Light Roast vs Dark Roast Appearance
Light roast coffee and dark roast coffee are literal terms. Both roasts start from the same green coffee beans, and dark roasts are roasted longer or hotter than light roasts, which makes them visibly darker when they’re done.
There is no set color for a light roast or a dark roast since unroasted coffee beans vary by color and the amount of roasting required differs between different beans. However, a dark roast coffee made from the same bean as a light roast coffee will always be notably darker.
Typically, a light roast is somewhere in the color range between light brown/yellow/tan to medium brown, while a dark roast is very dark brown, bordering on black.
Light Roast vs Dark Roast Flavor
How a coffee roast looks matters very little in comparison to how it tastes, and light and dark roast coffees tend to have flavors that are highly distinguishable from one another.
One simple way of putting the difference between light and dark roasts is that a light roast of coffee is less “cooked” than a dark roast of coffee. Basically, a light roast is “rare,” while a dark roast is “well done.”
Since coffee beans have unique notes, and some have additional flavors added in, there is no general descriptor for how a light or a dark coffee roast tastes. However, you can compare roasts of the same beans to each other.
Generally speaking, a light roast has more nuanced flavors while a darker roast has more of a monotone flavor.
Let’s go back to our rare versus well-done analogy and think of it like a steak. A well-done steak has a more consistent meaty flavor, while a rarer steak has more ‘notes’ because it retains more of its fat and juices. They’re both still steak, but one tastes quite different from the other.
The same is true of light versus dark roast coffee beans. Lighter roasts retain more of the bean’s oils and flavors, while darker roasts dry out more and end up with a more consistent flavor.
If you drink espresso, you’re probably used to some dark roast coffee. Dark roasts dominate the espresso coffee market.
Light Roast vs Dark Roast Caffeine
A difference in caffeine is one of the most common misconceptions about dark versus light roast coffees.
Many people think light roast coffee has more caffeine because it loses less of its juice during the roasting process.
Others think dark roast coffee has more caffeine because… well… it just tastes like it should. Stronger coffee flavor should mean more caffeine, right?
Let’s break it down.
Does dark roast have more caffeine?
No. Dark roast coffee is never going to have more caffeine than light roast unless you are actually using more of it during the brewing process.
Whether you measure beans or ground coffee, a light roast coffee is always going to have more caffeine by volume than a dark roast.
This is due to the change in bean size and density during the roasting process.
Does light roast have more caffeine?
Yes. By volume. Due to the density of the bean, a tablespoon of light roast will have slightly more caffeine than a tablespoon of dark roast.
However, if you measure by weight, dark and light roasts will have virtually the same amount of caffeine. It’s about the density, and that is only measurable by weight.
Which roast of coffee is the least acidic?
Dark roasts of coffee are less acidic than light roasts of coffee because the natural acids in coffee beans break down during the roasting process.
This is becoming less and less true, however,, thanks to dedicated effort and favorable science. Many coffee producers are now making low-acid batches of lighter roasts, providing variety for those who need a low-acid blend.
Which coffee roast is best?
Which coffee roast is best – dark or light – is, of course, entirely subjective and comes down to flavor.
Dark roast is the more popular of the two and the roast you are most likely to get at a coffee shop. Case in point, until they introduced their “Blonde Roast” in 2012, Starbucks had no light roast at all. That’s more than 40 years in business on dark roast alone.
It’s no wonder a dark coffee roast is what most people probably think of when they think of “coffee flavor.”
That said, a light roast can be a mighty fine roast if you like the subtle notes in a coffee blend. If your coffee is fruity or chocolatey, you’ll get more of that fruit or chocolate flavor in a lighter roast than in a darker roast.
The light roasts of two different coffees can taste worlds apart, which can be interesting or shocking in a bad way. Occasionally, a light roast of coffee won’t even taste that much like coffee.
Dark roasts tend to have more consistency, with darker roasts of two different coffees tasting considerably more alike than light roasts of the same two coffees.
Medium Roast Coffee
A battle between light and dark coffee need not be waged, because there is already a happy medium. A literal medium.
Medium roasts of coffee combine the best of dark and light coffee roasts, roasting long enough to enhance the “coffee” flavor, while roasting for a short enough time to maintain the coffee’s unique tones.
There’s no guarantee a medium roast will be your favorite roast – dark is still the most popular – but if you’re dissatisfied by both a dark and light roast of coffee, try meeting somewhere in the middle.
Coffee roasts come on a spectrum, so you don’t have to settle for an extreme.