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Dark Roast vs. Light Roast Coffee – Which Has More Caffeine?

It’s commonly thought that dark roast coffee is stronger, more potent, and ultimately more caffeinated than light roast coffees because of its bolder flavor and darker color. However, here’s the truth:

When brewed by volume (as in most regular coffee machines), dark roast coffee has less caffeine than light roast because some of the caffeine is lost during the roasting process.

Yes, that’s right. Your dark roast coffee may not be as potent as you think. Next time you’re picking up your morning coffee, try a light roast and see if you feel extra “productive” in the morning.

  • bobby

    bull crap the caffeine stays the same, do your homework fool

  • Mike A

    Wrong! Roasting does reduce the amount of caffeine. However, the extra roasting also shrinks the bean. As a result, more beans are required to make a cup of dark roast coffee than light roast. These exttra beans significantly increase the amount of caffine in a cup of coffee when compared to light roast.

    • Paul Dipshite

      Idiot. Read everywhere and they all say dark roast has less caffeine, your wrong! You can’t even spell so why would we listen to you. Moron! Caffine……lol caffeine!

    • Mike A

      Congratulations, you can use spell check. Does that make you feel like a big boy? Any moron can use spell check, and the lowest form of life are those who troll the Internet to criticize the grammar of others who type their posts with the small keyboard of a phone. I penned three published books (including one on grammar). How many books have you published?

      I know you unable to get by without spell check, because your post is laden with grammatical errors that spell check would not catch. For instance “they all say dark roast has less caffeine” is an independent clause and should have been preceded by a comma (spell check didn’t tell you that huh?). Additionally, “your” should be written as the contraction “you’re” when you typed “your wrong!” I suggest that you not throw stones when you live in a glass shanty

    • Sean

      Have you ever roasted coffee? The beans expand from raw to light by about 40-50%, and an additional 10% going to dark. I roast coffee on a regular basis and have compared the two beans side-by-side. I was surprised by this fact, and I can send/post pictures somewhere if desired.

      • Papa Joe

        Sean you may be a roaster but you are not a scientist! Yeah sure the bean may expand in size, but the roasting process makes the bean lighter as roasting causes the bean to become less dense (…because it’s expanding…) as it is loosing it’s moisture content. As the caffeine content in a coffee bean is NOT affected by the roasting process (caffeine is relatively stable during roasting, with only very slight changes in content levels), but it’s moisture content and density (thus it’s mass) is affected – there is a higher ratio of caffeine content to the rest of the bean content. Therefore, as the other guest above me noted rather clumsily, more beans are required to make a shot of coffee with dark-roast compared to light roast, there will be a slightly higher caffeine content. What will change your caffeine content, and the way you experience that caffeine, is the species of coffee –
        robusta has higher levels than arabica, but furthermore there is even more difference in caffeine content between species within each bean type – and the way you brew and thus drink your coffee. If you have an espresso, you get the same caffeine content as a regular latte, but you generally ingest it much quicker and thus it floods your system much quicker. Also, as caffeine is absorbed through the mouth, oesophagus and ultimately the stomach, your stomach contents will affect how you ingest the caffeine.

        So there ya have it grindhounds

  • kotanmj

    My nephew owns a coffee company and he says that the darker the roast the lower the amount of caffeine is correct. Roasting coffee beans makes them expand, not shrink, so the difference caused in the roasting process expands the beans and causes a loss of caffeine. Thanks, Nosh, for the information. Every one of us would expect the reverse to be true.

  • Josh

    Mike A is right. The molecular structure is too strong to break apart during the roasting process. However, the darker it’s roasted the less the bean weighs and as a result you need more beans to get the right ounces of grounds when you brew coffee. Darker roast coffee beans don’t have more caffeine but a cup of dark roast coffee has more caffeine simply because it uses more beans.

  • adion81

    Actually, the truth comes out to the individually brewed cup of coffee. The roasting process first expands the bean to twice it’s size, and then it loses mass from there. Yes it is true that darker roasted coffee beans have less caffeine than lighter roasted beans. It’s also true that it takes more beans to roast a dark roast than a light. But since most of the mass loss in the roasting process is water, they both have relatively the same amount of caffeine. It all depends on how much coffee grounds are used. In Louisiana, we like to have our coffee strong, and put more scoops of grounds than the normal American. The actual difference between light and dark is mostly flavor.

  • K K Watts Jacobsma

    The difference in caffeine between light and dark roast coffee depends a lot on how it is measured…by volume or weight. Even though a bean’s caffeine content changes little during roasting, a bean’s caffeine per volume and per weight is altered considerably—not because the caffeine changes but because the size and the weight of the beans change. The longer a bean is held in the roaster, the darker in color, lighter in weight, and larger in size it becomes.

    So, when do differences in caffeine content come into play? This happens when roasted coffee is measured for brewing or packaging. Since a bean loses weight (mainly water) during roasting, its caffeine content by weight increases while its caffeine content by volume decreases. Confused yet? Let’s put this principle into practice by measuring some coffee.

    Dark-roast coffees measured by volume with a scoop contain fewer coffee grounds due to their greater volume, resulting in a weaker brew and less caffeine per cup than a light-roast coffee measured in the same manner. Bottom line, you’re not getting the most from a dark-roast coffee if you measure it this way.

    On the other hand, dark-roast coffees measured by weight require more coffee grounds for brewing since they weigh less than a coffee roasted lighter, resulting in a full-flavored brew and more caffeine per cup than a light roast. Measuring coffee by weight is the method adopted by many folks devoted to their joe and strictly adhered to by any coffeehouse worth its salt—or should we say the price of a cup.

    • Don Graham

      That’s the best explanation I’ve ever heard! It makes perfect sense too. Thank you. I’ve had many an argument with friends etc. I’ll be forwarding this to them.

  • Jin_and_what

    Pardon me for jumping into this discuss after a year. The term “loss of caffeine” has to be used carefully here. IMO, During the roasting process, there is actually barely any loss of the caffeine content. Like many have said: the longer the roasting process, the darker, lighter, and bigger each piece of beans gets. So, while retaining the same amount caffeine content, 1) because of the lighter weight of beans, the Caffeine Percentage By Weight increases, dark roast will require less weight to achieve the same level of taste. 2) because of the bigger size of beans, the Caffeine Percentage By Volume reduces, dark roast will contain less caffeine than light roast if measured by the same volume, naturally it will require more dark roast beans in volume to achieve the same level of taste.

  • It’s in a light roast that the beans are at their highest acidity as well, though not to be confused with being bitter. Bright, lively, sometimes fruity, the light roasts will become less so if they’re roasted longer. Needless to say, the smell and taste will change as well –

  • Avery

    . . . its a conspiracy ! I might get killed for saying this ! people who love coffee get dark cause they think it is stronger . . . so they have to buy move to get their fix . .. . . . .normal people will not buy a lot so they get light marketed to them and it does not matter . . . . . .. There are agents on the internet used to send disinformation and tell you there is no difference but they are just trying to cover it up man ! pray for me ! I have said to much and might be assassinated ! People need the truth !!!!!

  • Never know these differences between Dark Roast and Light Roast Coffee! Informative post! this is “How To Determine the Degree of Roasted Coffee Beans by Eyesight” also a informative post about these:

  • Lori Bryn

    Write the same small article about milk frothers, as they did here