· 4 min read
Does dark roast have more caffeine?
Light roast vs dark roast caffeine: by weight they are close, by the scoop light roast wins a little. Why, with the studies named.
No, not in any amount you would notice. Weighed gram for gram, a light roast and a dark roast carry about the same caffeine. Measured by the scoop, light roast gives you slightly more, because its beans are denser and a scoop holds more coffee. In the cup, a careful 2024 study found dark roasts came out a little lower when everything else was kept the same.
Why roasting barely touches caffeine
Caffeine is a tough molecule. It does not burn off the way sugars and acids break down in the roaster. At normal air pressure it turns straight from solid to gas at about 352°F (178°C), and the 2024 study described below suggests that inside a roasting bean it holds on past that point.
The rest of the bean is far less stable. Water leaves first. Then sugars and acids break apart, and some of what they become escapes as smoke. So the bean loses weight while most of its caffeine stays put. In that study, a roast that had lost about 12 to 14 percent of its weight generally counted as light, and darker roasts lost more.
That is the root of the whole question. A dark roast bean is lighter than it was, holds most of its original caffeine, and has swollen in size. Whether that makes it "stronger" depends on how you measure it.
By weight or by scoop
If you weigh your coffee, the difference is small. Losing weight while keeping caffeine can even leave a gram of dark roast with a touch more caffeine than a gram of light roast. Researchers disagree about how much, and the gap is small either way.
If you use a scoop, light roast gives you more. Dark roast beans puff up and lose mass as they roast, so a level scoop of them holds fewer grams than a scoop of light roast. Fewer grams of coffee means less caffeine, however the beans were roasted. You can see this at home: weigh a level tablespoon of a light roast and one of a dark roast, and the dark will come out lighter.
This is one reason we suggest weighing coffee instead of scooping it. The coffee to water ratio guide shows how.
What a controlled study found in the cup
In 2024, physicists and chemists at Berry College and Drexel University published a study in Scientific Reports that tried to settle the question. They roasted two Ethiopian coffees, one washed and one natural, to a range of roast levels. Then they ground and sieved every batch to the same particle size and brewed each one in an AeroPress at 15 parts water to 1 part coffee.
Their findings:
- Under identical brewing, dark roasts generally produced less caffeine in the cup than light and medium roasts.
- The most caffeine came from roasts that had lost about 14 to 16 percent of their weight, which the authors describe as generally light to medium.
- Caffeine in the brew began to drop for roasts taken past a drop temperature of roughly 400 to 420°F, which the authors read as some caffeine escaping late in the roast.
- Darker roasts were more porous under the microscope, but gave up less dissolved coffee overall, which is why the cup came out lower.
The same paper counts more than 20 earlier studies on roast and caffeine and notes how much they disagree. The most common earlier result was no effect at all. Some found more caffeine in light roasts, some in medium, some in dark. Differences this small are easy to swamp with a change of grind, water or method.
What changes caffeine far more than roast
The size of your dose, the size of your cup and the way you brew all matter more than the color of the bean. The FDA lists 113 to 247 milligrams of caffeine for 12 fluid ounces of regular brewed coffee. That spread comes from different beans and doses in different brewers. Roast level is a small part of it.
Species matters too. Robusta, the other main coffee species, carries a good deal more caffeine than arabica. All three of our coffees are arabica. For the numbers by drink and brew method, see how much caffeine is in coffee.
Why dark roast tastes stronger
Dark roast tastes stronger because it is more bitter and heavier on the tongue, and most of us read bitterness and weight as strength. Caffeine is bitter, but it accounts for only part of the bitterness in coffee, and much of the bitterness in a dark roast comes from compounds made in the roaster. Light vs medium vs dark roast covers what else the roast changes.
So if you love a dark roast, drink it for the taste. Our dark roast from Guatemala, grown at El Mirador in Huehuetenango at 1,700 meters, has hints of toasted almond and brown sugar, with a little orange at the end, and it is built for espresso and milk. If you want more caffeine from it, use a little more coffee. Changing the dose moves the caffeine much further than changing the roast.
