Light, medium or dark roast: what is the difference?

Almost every bag of coffee beans says it: light, medium or dark roast. But what is the difference between light, medium and dark roast, and what do you notice in your cup? The short answer: the roast level indicates how long and how far a bean has been roasted. That changes the color, the flavor, and also how best to brew the coffee. Most explanations skip that last point, while it helps you every morning.

What roast level means

Green coffee beans are hard, grass-green and don’t taste like coffee yet. Only during roasting do the color and aromas we know develop. The bean loses moisture, expands and becomes browner the longer the roasting lasts.

Halfway through, the bean makes an audible crack, the so-called first crack: the moisture inside expands and breaks the structure open. A light roast is stopped shortly after. A medium roast goes a bit longer. A dark roast lasts the longest. There is no legal boundary between the three: each roaster uses their own definitions. Light, medium and dark are therefore guidelines, not exact measures.

The difference between light, medium and dark roast

• Light roast: the shortest roasting. The bean is light brown and the original character of the origin remains clearest. Light roasts usually have more bright acids and a lighter body.
• Medium roast: the middle. The bean is medium brown; some of the brightness gives way to the round, warm tones that develop with longer roasting.
• Dark roast: the longest roasting. The bean is dark brown and the flavor is more determined by the roasting itself: more body, less acidity, and with longer roasting also more bitterness.

Two misconceptions are common. Dark does not automatically mean stronger: how strong your cup is mainly depends on the amount of coffee per amount of water. And a shiny, oily bean is not a feature of every dark roast; dark roasted beans can also feel dry.

Which roast suits which brewing method?

There is no forbidden combination, but there are rules of thumb. Light roasts come best into their own with filter coffee and pour-over: those methods highlight fresh, clear flavors well. Dark roasts are popular for espresso and fully automatic machines, and they hold up well with milk. A medium roast is in between and is the most versatile choice.

At Coffee Brothers it looks like this. All three of our beans are convection roasted, with hot air, and feel dry:

• Light Roast: Ethiopia and Vietnam, 80/20 arabica/robusta, the shortest roast of the three. Best as filter coffee or pour-over, also suitable for fully automatic machines.
• Medium Roast: Ethiopia and Vietnam, 85/15 arabica/robusta. Works with every brewing method, black or with milk.
• Dark Roast: Brazil and Ethiopia, 80/20 arabica/robusta, dark roasted. Made for espresso and fully automatic machines.

Switching roast? Adjust in four steps

A dark bean behaves differently than a light one. It is lighter in weight, airier in structure and dissolves more easily in water. Those who switch roast and keep everything else the same often get a disappointing cup. Here’s how to avoid that:

1. Weigh instead of scooping. Dark beans lose more weight during roasting and expand more. A scoop of dark coffee usually contains fewer grams than a scoop of light coffee. With a scale, your ratio stays the same, whichever roast you use.
2. Adjust the grind size one step. Dark roasts dissolve faster: grind them one step coarser. Light roasts need a bit more: grind them one step finer. How grind size works per brewing method is explained in our grind size explanation.
3. Choose your water temperature within the range. The usual range is between 90 and 96 °C. Start at the lower end for a dark roast and at the upper end for a light roast.
4. Taste and change one thing at a time. Sour and thin means too little extraction: grind finer or use hotter water. Bitter and dry means too much: grind coarser or use slightly cooler water.

After two or three cups you have your new setting. Write it down so you don’t have to search again next time you switch.

How to choose the roast that suits you?

Start with how you drink your coffee. If you mainly drink black filter coffee and like a fresh, light cup, try a light roast. If you make espresso, use a fully automatic machine or drink your coffee with milk, a dark roast is more obvious. If you’re unsure or often switch methods, medium is the safest starting point.

Taste remains personal. The only real test is the same brewing method with two roasts side by side, both properly adjusted.

Frequently asked questions

What is the difference between light and dark roast?

Light roast is roasted shorter than dark roast, so the bean is lighter in color and retains more of the origin’s character. Dark roast is roasted longer and tastes fuller and less acidic, with more influence from the roasting itself.

Is dark roast stronger than light roast?

Dark roast is not automatically stronger; how strong a cup tastes mainly depends on the amount of coffee per amount of water. A dark roast tastes fuller and has less bright acids.

Which roast is best for a fully automatic machine?

For a fully automatic machine, medium and dark roasts usually work best, provided the beans feel dry and are not oily. Oily beans can dirty the grinder and brewing group faster.

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