As a sommelier and brewer, I have had the opportunity to experiment with different grinds for pour over coffee and I can confidently say that a medium-coarse grind is the best choice. This grind size is similar to that of a French press, but with slightly smaller particles. When you run your fingers through the grounds, they will feel smoother compared to a chunkier grind.
The reason why a medium-coarse grind is ideal for pour over coffee is because it allows for a balanced extraction. If the grind is too fine, the water will have difficulty passing through the coffee bed, resulting in a slow and over-extracted brew. On the other hand, if the grind is too coarse, the water will pass through too quickly and the flavors may be underdeveloped.
With a medium-coarse grind, the water is able to flow through the coffee bed at a steady pace, extracting the desirable flavors without over-extracting. This grind size strikes a good balance between flavor extraction and clarity, resulting in a clean and well-rounded cup of coffee.
It's important to note that the grind size can also vary depending on the type of pour over device you are using. If you have a cone-shaped pour over, such as a Hario V60, a Chemex, or a Kalita Wave, then a medium-fine grind is more suitable. This grind size is slightly finer than medium-coarse, allowing for a slightly slower extraction and more control over the brewing process.
In my personal experience, I have found that using a medium-coarse grind for pour over coffee yields excellent results. The flavors are well-extracted, the coffee is clean and balanced, and there is a pleasant smoothness to the cup. However, I encourage you to experiment with different grind sizes and find the one that suits your taste preferences and brewing equipment. Each coffee bean and brewing method may have unique characteristics that can influence the optimal grind size.
To summarize, the best grind for pour over coffee is a medium-coarse grind, which is similar in size to a French press grind but slightly smoother. This grind size allows for a balanced extraction and results in a clean and well-rounded cup of coffee. If using a cone-shaped pour over device, a medium-fine grind is more suitable for a slower extraction and greater control over the brewing process.