Pressure

is the ratio of force to the area over which that force is distributed. Pressure is force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure (also spelled gage pressure) is the pressure relative to the local atmospheric or ambient pressure. While pressure may be measured in any of force divided by any unit of area, the SI unit of pressure is called the pascal (Pa) after the seventeenth-century philosopher and scientist Blaise Pascal.

In coffee brewing pressure is used to improve . By using pressure, the brewing temperature can be considerably lowered. Using pressure, undesirable compounds, that are only soluble at high , are not extracted. This improve the aroma and taste profile of the coffee.

Pressure is used in and percolators, as well as some single serve such as  and .

coffee is at 9 bar pressure which is equivalent to 9 times the amount of pressure present at sea level.

The presence or absence of pressure in creates very different results in the final cup of coffee. Extracting under pressure, as with espresso, yields a that that contains more coffee compounds such as cafestol and kahweol and is considered a much fuller cup. However, brewing coffee without pressure and through a creates a much cleaner cup. The absence of some of these properties extracted at high pressure is an advantage to many coffee drinkers who prefer not to consume these compounds for health reasons or because of preference.