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Today’s Tiny Lesson: Setting Your Grind Size

Getting back to the grind.

by Ever Meister | July 01, 2021

Hello, coffee lover! We know brewing great coffee can seem really intimidating, and that the sheer number and complexity of brewing guides out there don’t help matters, so we’ve decided to help. Rather than think about coffee-brewing expertise as something you have to have right now, let’s look at it like a relay race: It’s much easier to run a marathon for the first time if you break it up into chunks.

Now that you’ve gotten your recipe basically dialed in, it’s time to throw your grinder into the mix.

If you’re intimidated by your own grinder, you’re not alone: Even baristas in cafés are taught to fear their grinders sometimes! I’ve personally been called in as a trainer in coffee shops only to find a handwritten “Don’t touch the grinder!!!” sign hanging by the espresso machine, while the manager is simultaneously wondering why the coffee tastes so bad.

The truth is, your coffee needs you to touch your grinder, and in order to be a master of your own countertop coffee bar, we want to help you feel confident as you calibrate, make changes, and even experiment with different grind sizes for different brew methods. The grinder is to a barista as the oven is to a cook: Would you set your oven at 350°F no matter what you were making? Of course not — and the same is true with your grinder. Tools are only really useful when you use them properly.

You may remember from this excellent primer on grind size that how you brew will dictate how you grind, at least somewhat; If you’re a daily French presser, for example, your typical grind size will be quite coarse; if you’re more of an espresso type, you’ll usually grind quite fine. In between there, however, is a whole spectrum of grind sizes, a rainbow of opportunities for better flavors.

We’ll walk you through an easy-breezy exercise in grind-size calibration, but first we want you to take a close look at your grinder and its adjustment collar or knob. Most grinders use numbers as a way of indicating grind size: For instance, on a Baratza grinder, smaller numbers usually indicate a finer grind, while larger numbers indicate a coarser grind. Your grinder might be “stepped,” which means that you can make a limited number of set adjustments — from a three to 3.5, for instance — or it might be fully adjustable in smaller increments, so that you could go from three to 3.1 or even in between 3.1 and 3.2. When in doubt, check the manual (or simply grind some and see).

Remember that when you’re adjusting for a finer grind, you’re moving the grinder burrs closer together so that they can cut the coffee into smaller particles (which will extract them faster); the opposite happens when you adjust for a coarser grind (for a slower extraction), the burrs will be farther apart. One of the things that make folks nervous to make adjustments is that they won’t remember which way they tweaked the grinder, or how much — that’s where this exercise comes in.

Just like with our last exercise, you’ll brew coffee three times: Once using the grind you usually use, followed by a batch that’s a little coarser and then one that’s a little finer. You’ll also want to time the brew, which will help us connect the dots among our extraction variables. (We’ll talk more specifically about brew time in the next tiny lesson, so it will come in handy to have it jotted down.)

Step-by-step instructions

  1. Grind one batch of coffee the way you normally do, and before you brew, take notes about the grind size as indicated on you grinder. It can be helpful to keep a physical record of the grind size for reference: You can grind one to two grams extra and use a bit of packaging tape to adhere a small sample to your worksheet
  2. Brew the coffee as normal, but be sure to record how long the batch takes to brew: Start the timer as soon as water and coffee make contact, and stop the timer when the last drop of brewed coffee comes out. Pour the finished brew into a carafe or mug and set aside to cool
  3. While the first batch is cooling, brew again — this time grinding the coffee slightly coarser than in step one. Use the same amount of water that you usually do. Remember to write down your recipe on the form
  4. Repeat steps one and two
  5. Brew one last time, grinding the coffee slightly finer than in step one —and take those good notes, of course
  6. Taste!

As you’re tasting the coffees, consider the same things as last time:

  • Do any of the three brews taste more bitter than the others? You might notice a smoky or pungent taste up front and a long or lingering aftertaste. You may also see a longer brew time.
  • Do any taste sour? Check for a puckering sensation in your mouth and a short aftertaste. This might accompany a shorter brew time.
  • How about sweet, can you detect one that seems sweeter? It might also have a more balanced or nuanced flavor.

What we’re attempting to do here is calibrate our recipe to our grind size: We want to make sure not only that we have the right amount of the raw materials, but also that we are optimizing those raw materials by controlling their interaction. Same as last time, sweetness is what we’re looking for here, because a well-extracted coffee should express enough of it to balance out the natural bitterness that can be exaggerated by over-extraction, as well as soften the cup enough to side-step under-extracted sourness.

Did you find that any of the batches tasted sweeter than what you normally brew with? You might want to adjust your grind size finer or coarser to try to maximize that flavor. If it’s too close to call, try repeating the experiment with a smaller adjustment (if possible).

Good luck, have fun, and happy brewing!