Understanding Pressure: How Many Bars You Need for Great Coffee and Espresso
When it comes to brewing espresso, pressure plays a crucial role in determining the flavor, texture, and overall quality of the final shot. You’ve likely heard people mention “bars of pressure” in conversations about espresso machines, but what does that really mean? And how many bars do you actually need to make the perfect espresso? Whether you’re using a home machine or exploring espresso at a deeper level, understanding the relationship between pressure and extraction is essential.
What Does “Bar of Pressure” Mean?
The term “bar” is a metric unit of pressure. One bar is roughly equal to the atmospheric pressure at sea level, about 14.5 pounds per square inch (psi). In espresso machines, pressure is used to force hot water through tightly packed coffee grounds, extracting oils, flavors, and aromas that define a good espresso.
Without enough pressure, water may pass through the grounds too slowly or unevenly, leading to poor extraction. Too much pressure, on the other hand, can result in over-extraction and a bitter taste. Striking the right balance is key.
Why Pressure Matters in Espresso Brewing
Espresso is not simply strong coffee—it’s a brewing method that requires precise conditions, including high pressure, fine grind size, and short brew time. The role of pressure is to extract a concentrated shot of coffee in about 25 to 30 seconds. This quick and intense process is what gives espresso its signature crema, body, and complex flavor.
The proper amount of pressure ensures that water evenly saturates and passes through the coffee puck, pulling out both soluble compounds and emulsified oils that contribute to the rich mouthfeel and aroma of espresso.
What Is the Ideal Pressure for Espresso?
The gold standard for espresso brewing is 9 bars of pressure. This level is considered optimal for achieving a balanced extraction. It’s strong enough to produce a rich, flavorful shot, yet controlled enough to avoid over-extraction or burning the coffee.
Many espresso machines are marketed with 15 or even 19 bars of pressure, but these figures often refer to the pump’s maximum capability, not the actual pressure used during brewing. In most cases, machines still regulate the brew pressure to around 9 bars, especially in well-designed systems.
Is More Pressure Better?
Not necessarily. While high pump ratings can sound impressive, more pressure doesn’t automatically lead to better espresso. If the machine doesn’t manage pressure correctly or if the coffee grind, dose, and tamp are off, even high pressure won’t save the shot.
In fact, pressure that’s too high can force water through the puck too aggressively, which may result in uneven extraction, channeling, and bitter flavors. Consistency and control are more important than reaching the highest number on the gauge.
Can You Make Espresso with Less Than 9 Bars?
Some machines and manual espresso tools operate below 9 bars—usually in the range of 6 to 8 bars—and can still produce a great shot. Lower pressure can create a softer, sweeter espresso with less crema and body. It might be preferred by those who enjoy more delicate or nuanced coffee profiles.
However, lower pressure often requires careful adjustment of other variables, like grind size, water temperature, and extraction time, to achieve a satisfying result.
Pressure in Regular Coffee Brewing
It’s worth noting that pressure isn’t typically a factor in standard coffee brewing methods like pour-over, drip, French press, or cold brew. These rely on gravity or immersion rather than mechanical pressure. For these methods, grind size, water temperature, and brew time are more influential than pressure.
That said, some brewing tools that use pressure—such as certain portable coffee devices—may operate at lower bar levels, offering espresso-style drinks without needing a full espresso machine.
In the world of espresso, pressure is a critical ingredient that brings the shot to life. While 9 bars is the widely accepted standard for optimal espresso extraction, understanding how pressure works—and how it interacts with other brewing variables—can elevate your coffee experience. Whether you’re dialing in your espresso machine or just curious about what makes that tiny, powerful cup so special, paying attention to pressure can help you brew with more precision and confidence.
