What does the number on the measuring cup mean?

The number on the measuring cup represents the measure of coffee beans to use per cup of coffee. Number 1 stands for 1 cup and refers to 22g of coffee beans. This corresponds to the number in the lower half of your brewing vessel. For a perfect brew of 1 cup of coffee, we recommend that you also fill the water to where it says "1" on the bottom. This should yield 1 US standard mug of coffee, approximately 350ml or 12oz of liquid.