Patented by an Italian inventor in the late 19th century, espresso machines use a pressurized brewing process for a strong, silky coffee. And unlike other coffee-making techniques, the output should be measured by weight instead of volume (the CO2 based crema on the top can skew the results if you use the latter).
The coffee dose you use to make espresso usually hovers around the 1:2 ratio by weight—that means the amount of ground coffee you use will yield twice as much espresso. For a double shot (the standard serving at most American coffee shops), you’ll need between 18 and 21 grams depending on your tools.
That means your espresso will cost anywhere from 24 to 28 cents—before you introduce any milk or sweeteners.