How to Adjust and Calibrate Your Coffee Grinder

Do you know why the taste of your afternoon coffee is different from the taste of morning coffee? The coffee beans, a clean machine, and a well-calibrated grinder are responsible for your coffee taste. So how do you adjust it? 

Here are the key steps: 

   1. Pour a shot of coffee through your machine with the grinder at any setting.

WATCH: How is this coffee coming out of the machine? 

• Streaming out like water? The coffee is too coarse and you will need to make the coffee finer. 
• Coffee just dripping out? The coffee is too fine and needs to be dialed back to be coarser.

    2. Re-pour another coffee shot and monitor for signal and make very small adjustments to your grinder based on observations above.

**Note when making any adjustments to the grinder, make sure to run at least 2-3 doses, in order to get rid of any old coffee still in the grinder. 

    3. Keep repeating this method until you find the perfect coffee shot, which     should look like this:

  4. Once your shots are coming consistently, without streaming out like water     or dripping slowly, you can leave your grinder dialled in here and then just       tweak it finer or coarser.

The rule of thumb says that every line makes two to three seconds of change in extraction time. It depends on the age and condition of the blades of the grinder as well. We like to think of coffee grinding as macro or large scale, while espresso is micro or small-scale. Be aware when you are making changes to espresso grind the adjustments should be tiny. It’s best to adjust 1 notch or a ¼ inch at a time.

Calibrating your coffee grinder is something that you should be doing (ideally) every morning. And if there is any change in weather, you have to adjust it properly to achieve a correct grind density. 

The coffee machine can also collect oil if you overuse it and do not clean it regularly, resulting in an unpleasant taste. You can check out our cleaning products if you’ve been postponing cleaning your coffee machine and make sure it’s ready for your next cup of coffee!

How important is it to adjust the grinder?

If you have excellent coffee beans, an excellent machine, and a skilled barista, but do not have the coffee grinder adjusted for the day's conditions, the coffee produced can be of poor quality: either watery and weak, or bitter and burned. In fact, most of the time that you get an espresso that is of poor quality, the reason is that the grind was wrong for the atmospheric conditions at the time. No amount of tasty syrup or fancy latte art can hide the poor quality of espresso that was badly extracted because the grind was off. 

• Weather Conditions: When the weather changes, it immediately impacts the grinder calibration. Coffee responds to different environmental factors like heat and moisture. Therefore, you will need to factor in the time of the day when adjusting your grinder.
• Coffee Age: It refers to the roasted date of coffee beans. You can find it challenging to extract fresh coffee as it has high moisture and carbon dioxide gas. It makes it harder to pull, but older coffees are more porous. 

Ideally, use a coffee bag between seven to 28 days from roast. Shop for a fresh bag of coffee beans here.

Therefore, if your hopper is close to being empty, the grind will come out coarser. You can avoid this by keeping the hopper half-full.

Overheating the grinder, water pressure fluctuation in the coffee machine, and inconsistent tamping are also reasons for a fluctuating calibration. 

What is happening in the grinding process?

Each coffee grinder is equipped with two grinders (flat or conical) that cut the coffee beans into smaller pieces, the closer the grinders are, the smaller the size of the ground coffee particles will be. As the particles become finer, they can be compressed closer to each other making it more difficult for water to pass through. This will slow down the extraction time of the espresso.

The same theory works in reverse. If the grinders are moved away the grind becomes coarser and these larger particles once pressed will remain more distant from each other, which means that the water will pass through them more quickly, speeding up the extraction of the espresso.

We often give the example of pouring a glass of water into a bucket with sand and into a bucket with gravel. The water will take much longer to cross the bucket with the sand because the small particles slow down the flow of water.

A first evaluation, certainly not too effective, of the coffee grinding can be carried out by taking a little ground coffee between the fingers, evaluating its consistency which must be soft and "dusty" but with a slight roughness. Obviously this will only be useful the first time we use a coffee grinder to be able to arrive faster in the correct grinding range and can never replace the actual setting that must be done with the espresso machine while keeping an eye on the scale and timer. 

One of the rules not to be forgotten in setting the correct coffee grinding is certainly to make all the settings with the double filter holder which, compared to the single filter holder, in addition to having a better extraction, has the advantage of a greater consistency of extraction.

Each coffee, blend or single origin will surely have a different recipe to be extracted at its best and the parameters we use in this article should not be seen as a law to be respected but only as a guideline that allows to have espresso almost certainly balanced in taste.

As in every recipe, it is the small details that make the difference and as coffee professionals, we pay attention to the grinding settings on a daily basis and if necessary we modify them to always serve customers the best possible coffee. With your potential and our know-how, you can make the best coffee at home. Have a look at our barista courses and take the first step to be a coffee connoisseur.