How to dial in your grind size for espresso

This is a perfectly dialled-in shot of espresso, but to make one, you have to solve an interesting problem. What's the right grind size to use for this coffee? There's two routes we can take to solve this. One is more basic and visual, and one is more fancy and scientific. For the first method, we'll be relying on a single visual cue, and that is, honey. This is the image you need to remember, because it's what we want the flow of our espresso to look like. If we pull our shot, and it gushes out much faster than the honey, like this, that's how we know we need to grind finer. But if the espresso flows slower than the honey, or barely drips out at all, that's how we know we need to grind coarser. So we keep adjusting the grind size until we get a flow of espresso that matches the flow of the honey. Now for our fancy and more scientific approach, we'll be using a scale that has a built-in timer. We'll place our cup on the scale and start our timer at the same time that we start our shot. Then we'll see how long it takes for the espresso yield to reach two times the weight of the coffee grounds that we used, and as a starting point, we want it to get there in about 30 seconds. This took a lot longer, and that's how we know our grind size needs to be coarser. And if it gets there much faster than 30 seconds, like this, that means we need to grind finer. So we keep adjusting our grind size until we get somewhat close to that 30 second shot time. And from there, we adjust based on taste. If the espresso is overly bitter, then grind a little coarser. If it tastes sour, then grind a little finer. Then you can take note of how long the espresso took to pull when you liked the way that it tasted, and note that for next time.