Espresso is split into two parts: the "dry" dose, which is the weight of your freshly ground coffee, and the "wet" dose, which is the weight of the extracted espresso. It's possible to determine the exact wet dose of your espresso before you brew it, which allows you to get the flavor you want without being overly precious about the grind size.

The process of turning the dry dose into a wet dose by adding water to coffee grounds is called extraction, and while the grind size and roast of your beans play essential roles in developing flavor, how long you choose to extract the grounds will determine the volume of your wet dose. The trick to getting this right is to use ingredient ratios.

Generally speaking, your wet dose divided by your dry dose equals your brew ratio. A classic example of a medium-strength espresso ratio is the Heritage espresso ratio, which is a 36.5-gram wet dose to an 18-gram dry dose, giving you a yield of 2, and you can fuss with ratios to your heart's content to find the yield that is right for you.

Tasting your wet dose can determine whether it's under or over-extracted, which will determine whether you need to increase or decrease your wet dose. An under-extracted yield with a sour, sludgy taste means you should increase your wet dose, while a watery and full over-extracted yield means you need to decrease your wet dose.