The Single Biggest Mistake Ruining Your Coffee, According to Experts

You can’t make good coffee without good coffee beans. But even if you buy the best beans, you can ruin your cup of joe by buying those beans pre-ground. Worst yet, buying whole beans and grinding them to the wrong size.

Grind size is arguably the most important factor in ensuring what you get out of your coffee beans is what the coffee roaster intended. From grinding your coffee to the wrong size to using the wrong kind of coffee grinder, here’s how to ensure your next cup of coffee achieves its maximum potential.

Why does coffee grind size matter?

As Deejay Newell, co-owner (and bean ambassador) of the the Montana-based Treeline Coffee Roaster, puts it: if you like the taste of coffee, then “grind size matters.” Two factors that rely on proper coffee ground size are contact time, as in how long water is in contact with the grounds, and extraction rate, or — in layman’s terms — how much of the coffee’s characteristics (i.e. sweetness, bitterness, caffeine, flavor) end up in the final cup.

“The size of the grind directly correlates with the amount of flavor you are extracting from the bean,” Newell says. “Different brew methods call for different grind settings because everything is ‘dialed in’ to extract the most precise flavor from the bean. The ‘one size fits all’ grind philosophy could leave your coffee tasting bitter or sour.”

If you’re having trouble determining where you’re going wrong with grinding your beans, use your taste buds to figure it out. Using French press brewing as an example, Newell says if the beans are ground too fine, the coffee will be over-extracted or bitter. “Too coarse? That means the water is running right through the grinds without ‘picking up,’ or extracting, the intended flavor on the way,” Newell says. The best part about grinding your own beans over buying the pre-ground stuff is that you can continually adjust your grind size with each batch rather than being stuck with a whole bag of coffee that’s not ground to match your brewing method.

Does it matter how I grind my coffee?

When shopping for a coffee grinder, you’ll come across burr grinders and blade grinders. Despite the marketing ploys (and low price tags) blade grinders are not coffee grinders.

“A nice burr grinder is going to allow you to dial in your grind setting exactly to how it’s brewing,” Natalie Van Dusen, Treeline’s founder and self-proclaimed chief caffeinator, says. “Using a blade grinder is equivalent to chopping your coffee into uneven pieces. This results in an inconsistent cup, because you have an inconsistent grind setting.”

When you’re brewing using two completely different sized grounds, you’re going to end up with a wonky brew. Water will spend less time with the coarser grinds, therefore reducing extraction, while water will also be spending too much time going through the finer grains. And no, the two won’t cancel each other out.

“We cannot stress this enough,” Van Dusen says. “If you are going to ‘splurge’ on anything for your coffee setup, let it be a grinder.”

Trade

What size do I grind for …

Espresso: Extra fine, like powdered sugar. Because water spends very little time with the coffee, since espresso is brewed through pressure, grounds should be super fine to provide just the right amount of resistance without completely stopping up the water.

Aeropress: Fine, like table salt. Aeropress is brewed almost like espresso, except is relies on immersion brewing and pressure. Coffee grounds should be fine, but not too fine to prevent over-extraction.

Drip/Pour Over: Medium, like sea salt. There will be a lot of minute differences between the size of your grinds for different drip coffee makers and pour-over brewers. However, a medium to medium-fine grind is where you should aim for a good cup of coffee.

French Press: Coarse, like a flaky seasoning. As an immersion brewing method, French press coffee needs enough surface area from coffee grounds to extra flavor while ensuring the grounds aren’t so fine that you end up with a bitter brew.

Cold Brew: Coarse, like small flakes of oatmeal. Because you use cold water and a long period of time to make cold brew, your grinds should be fairly coarse since extraction rate is slow. Coarser grounds will also ensure a cleaner cold brew because they’ll be easier to filter out.

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