An Intro to Coffee Roasts

A photo of the full spectrum of coffee roasts, from under-roasted to light roast to medium roast to dark roast to over-roasted coffee. All in piles.

What’s the difference between dark roast and light roast (and medium, for that matter)?

Coffee beans grow on trees, but unlike fresh fruit, they have to go through a few processes before they become the brew you know and love. Once the beans are processed on the coffee farms, they come to us in a raw—or green—state. In that state they are stable, but not yet ready to be ground and brewed. First, they need to be roasted, and how coffee roasts are done matters a lot to the final product. They’re generally narrowed down to three roast types: light, medium, and dark. But what’s the difference between roast types? Let’s break it down.


Roasting is the development of flavor. In some ways, this is no different than what happens when you cook at home. Just as when you sear a steak or bake bread, the application of heat browns the food and deepens the flavor. This is called the Maillard reaction. The same happens to beans in the roasting process.

Of course, terroir (the character of the area where the bean is grown), process, and species factor in, but the type and precision of the roast has the single greatest impact on the flavor in your cup. That’s why we place such an emphasis on skill. Execution is everything, and we pride ourselves on our expertise.


During the roasting process, the beans undergo changes in color, aroma, and flavor. Making the judgment call on when to pull a roast to accentuate the best characteristics of a bean is the roaster’s ultimate goal and requires using all five senses.

In general, lighter coffee roasts retain the fruitier characteristics of the bean (which is, after all a fruit), and darker coffee roasts bring out more caramel and cocoa notes.


There is virtually no difference in caffeine content between light and dark roasts—by weight. However, the more you roast the beans, the more they dry out, making them less dense than lighter roast beans. Consequently, a scoop of light roast beans is denser, and therefore has more beans, than a scoop of dark roast. If you want to get a consistent amount of caffeine, measure your coffee by weight.


Roast definitions are not standardized in the coffee industry. What one company calls a medium roast, another company will call a dark roast. What we call a light roast, others might call medium. Peet’s roasts have always skewed darker, because we like caramelized sweetness and body in our coffees. Extra-dark roasts, a style pioneered by Alfred Peet, are more roast-forward in taste. But, most importantly, we believe in finding the best roast for each coffee.

Above all, it takes great skill to usher a bean through roast development properly. Whether you drink a light, medium, or dark roast, the greatest difference you will taste is whether a coffee was roasted well or roasted poorly.


Since the flavor profiles of each roast are so different, brewing is key to the experience. Lighter roasts respond well to pour over and Chemex, as they accentuate the bright acidity and floral aromatics. Medium roast, with more of a balance of fruity and spicy notes, is an all-around performer, as comfortable as a cold brew as it is as a pour over. A French Press really brings out the body and depth of a well-crafted dark roast, and espresso absolutely demands a dark or extra dark roast to showcase those rich chocolate and nutty flavors. But everyone’s taste is different. Try different roasts with different brewing methods and see what works for you.

  1. Louise P Greenwood says:

    Loved that article! Would enjoy reading more about the roasting and growing process.
    Thank you.

  2. David Smith says:

    Thank you for posting this

  3. Timothy Squaires says:

    This email was very useful

  4. Hello
    I really enjoyed reading light, medium, dark roast and the different characters each one represents in the taste of coffee. Next up, I will read iced coffee versus cold brew and Papua New Guinea. Thank you for these very interesting reads!!!!
    Looking forward to baking your cookie recipe!!!
    Also below in the “Sign up” section you have a statement that reads “Don’t miss out our latest news by signing up” – it should read “out ‘on’ our latest news”.
    Thanks again, and have a wonderful day!!!

  5. I sincerely appreciate the educational initiative that Peet’s has undertaken in recent years. I find it fascinating to gain a better understanding of the what and why behind my longstanding, visceral conviction that this is the coffee I was meant to drink. After nearly 50 years of drinking Peet’s almost exclusively, it is a nice surprise to find another dimension to add to my enjoyment.

  6. Jane Staple says:

    Any specific advice for using the Aeropress based on roast levels? And any chance you might add Aeropress brewing notes in general to the various beans you sell? I have neither a press pot nor a Chemex (or other pour over), and sometimes wonder which way to guide my technique using what I do have (which sure beats only having a drip or pod machine).

  7. Teresa says:

    Thanks for this article. It’s so helpful to know all this, and more importantly to understand why I love dark roasts! I’m happy to know why there is a caffeine difference between the light and dark roast. And my mouth is watering for my Peet’s latte today. Can’t wait!

    I wonder if one can request different kinds of espresso when ordering a latte. Now I’d like it made with an extra dark roast. 🙂

  8. John Howard says:

    During the late 1940s, my father was a roaster for a small coffee company in Los Angeles. He recounted that a chimney sweep would show up each week to clean the ash out of the flue of the roaster. He was employed by the Coca-Cola Company. They would extract the caffiene from the ash to add to their beverages. Does this suggest that darker roasts might drive off more of the caffiene in the green beans and contain less in the roasted bean?

  9. Hoda says:

    Thanks for sharing these useful information!

    1. Vernon Williams says:

      Medium roast decaf?????

  10. Nancy K Brigden says:

    Please clarify
    I’m referring to the passage, “However, the more you roast the beans, the more they dry out, making them less dense than lighter roast beans. Consequently, a scoop of light roast beans is denser, and therefore has more beans, than a scoop of dark roast.”
    Shouldn’t a scoop of less dehydrated beans contain fewer beans?

  11. Elle says:

    Thank you! Very, very interesting and explains so much of what I have experienced as I’ve changed brewing methods. I have varied the beans I have delivered in my subscription over the year, but think I have landed on the perfect beans, roast and method for my tastes – Arabian Mocha Sanani brewed in my Italian espresso maker

  12. Six says:

    Did I miss it, or do you not mention how I can search for and buy a bag of your light roast beans? Sales prevention?

  13. Mary says:

    Good info! I’m passing it on to a couple of people who will also enjoy it. Thank you.

  14. Fliz says:

    Very helpful! Love the info on this site.

  15. Johnny says:

    So does Peets automatically roast to the optimum?
    I enjoy dark roast but want to try lighter roasts. If I change my profile will my current selections just be roasted differently?

  16. Marty W Watson says:

    Very good info for the uneducated.

  17. Patricio says:

    Very insightful! Thanks for sharing

  18. Melvyn Kirtley says:

    Thanks for the article, very interesting and helpful.

    Interesting you recommend pour over for the medium to light roasts. I always use Peet’s dark roast for my pour over and it works extremely well. Currently enjoying the last of the Red Mocha Haraz and Jamaican Blue mountain (both dark roasts) and incredibly super delicious.

  19. Cathy Copenhaver says:

    What would you recommend for those using an Aeropress?

  20. John Westbrook says:

    Nicely done & very informative. Thanks!

  21. shannonvue says:

    This article is very informative and I feel like you are reading my mind. thanks for sharing

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