One key step to getting great tasting coffee repeatedly is consistency, and one key to consistency in coffee brewing is using the same measurement of coffee and water each time once you have found a ratio you prefer. The question then is whether it is better to use volumetric measurements (e.g., scoops, tablespoons, cups, etc.) or weight-based measurements (e.g., grams, ounces, etc.). So long as you brew the same coffee repeatedly, you can make do with volumetric measurements and get good results. If you like to vary the coffee you drink on a daily or just regular basis, you will find that you can’t use the same volumetric measurement between coffees and get the same results.
Why? For much the same reason that coffee is sold by weight and not by volume. The issue has to do with size (i.e., volume) versus weight. Some coffee beans are much larger than others even though they weigh less and some coffee beans are much smaller but weigh more. This is true of both green/unroasted coffee and roasted coffee. As coffee goes through the roasting process, it begins to swell and increase in size. It also loses moisture and incrementally weighs less. This is why one pound of a dark roasted coffee will take up more space/volume in a coffee bag compared to one pound of a lighter roasted coffee.
Sometimes the volumetric difference can be striking. To illustrate this point, we wanted to share a photo of two bags of green coffee we purchased. Both bags weigh five pounds. One bag contains a coffee from India. The other contains a coffee from El Salvador. The difference in the volume (i.e., the amount of space each takes up) could not be more striking even though they both weigh exactly the same amount.
This is an extreme example, but illustrates the fundamental problem with volumetric measurements of coffee. If you tried to brew these coffees using the same volumetric measurement (e.g., five tablespoons), your brewing ratios would be really off as your getting a lot more of the El Salvadorian coffee in five tablespoons than you would the Indian coffee. The same holds true with using the same volumetric measurement for light versus dark roasted coffees.
This is why we recommend using a digital scale that is accurate to within a tenth of a gram or 0.1 grams. There are a number such digital scales on the market that are both reliable and inexpensive (i.e., less than $20). There are digital scales designed for coffee brewing that are much more expensive and offer a lot of valuable features. They are great but not necessary. Our recommendation is to look for digital scale with the following features: 1) accurate to 0.1 grams; 2) can weigh at least between 0-500 grams; 3) ideally has a built in timer; 4) uses easy to find batteries (AA or AAA) or is rechargeable; and 5) has high customer reviews online.
As always, we welcome your feedback and questions.