How to Fix Under Extracted Espresso

As a coffee lover, there’s nothing more disappointing than pulling an under-extracted espresso shot. The result is often sour, thin, and lacking the rich, balanced flavors of a perfect espresso. If you’ve faced this frustration, don’t worry—I’ve been there, and I’m here to help. Here’s how you can fix under-extracted espresso based on my own experience with troubleshooting.

What is Under-Extraction?

Under-extraction happens when water flows through the coffee grounds too quickly, not giving it enough time to extract the full range of flavors. This leads to a shot that’s weak, overly acidic, and sour. On the other hand, over-extraction results in a bitter, overly strong shot. The goal is to strike the perfect balance.

Key signs of under-extracted espresso:

• Sour or sharp acidity: It tastes sour in an unpleasant way, not like a refreshing citrus note.
• Thin body: Proper espresso should have a thick, syrupy body. Under-extracted espresso feels watery.
• Pale crema: The crema should be thick and golden-brown, but under-extraction results in a thin, pale layer.

1. Adjust the Grind Size

Grind size plays a crucial role in espresso extraction. Espresso requires a fine grind, but if the coffee is too coarse, water will pass through too quickly, causing under-extraction.

When I first started making espresso, I didn’t realize how small grind adjustments could dramatically impact the result. If your espresso is sour or weak, try grinding your coffee finer. A finer grind increases the surface area of the grounds, allowing the water to extract more flavor.

Quick tip: Make small adjustments—just one notch finer at a time—and test each shot. You’ll notice the flavor improves as you approach the optimal grind size.

2. Tweak Your Brew Ratio

The brew ratio refers to the amount of coffee grounds compared to the amount of water used. A typical espresso brew ratio is 1:2, meaning 18 grams of coffee yields around 36 grams of espresso. If your shot is under-extracted, you may be using too little coffee or too much water.

Experiment with your dose by slightly increasing it, giving the water more coffee to work through. Alternatively, reduce the yield (the amount of espresso produced) to create a more concentrated shot.

When I struggled with under-extraction, adjusting the brew ratio made a huge difference. If you’re not already using a scale to weigh your coffee and water, it’s time to start. Consistency is key when dialing in espresso.

3. Check Your Water Temperature

Water temperature is another critical factor in espresso extraction. If the water is too cool, it won’t extract enough flavor from the coffee grounds, resulting in under-extraction. The ideal water temperature for brewing espresso is between 195°F and 205°F (90°C to 96°C).

When I discovered that my espresso machine was brewing too cool, I realized it was causing my shots to taste sour. If your machine doesn’t have adjustable temperature settings, make sure it’s fully warmed up before pulling a shot.

If you can adjust the temperature, try increasing it by a few degrees. Just be careful not to go too hot, as that can lead to over-extraction.

4. Dial in Your Tamp Pressure

Tamping is the process of compressing the coffee grounds in the portafilter. If you tamp too lightly, water will flow through the grounds too quickly, causing under-extraction. Tamping too hard, however, can lead to over-extraction.

In my early days of espresso-making, I didn’t pay enough attention to tamping. I’ve since learned that an even and firm tamp is essential for proper extraction. You want to apply around 30 pounds of pressure when tamping.

Pro tip: Practice tamping on a bathroom scale to get a feel for 30 pounds of pressure. With time, you’ll develop a sense of the right force.

5. Adjust Your Shot Time

Shot time refers to how long it takes to pull an espresso shot. The ideal shot time is between 25 and 30 seconds. If your shot pulls too quickly (in under 20 seconds), it’s a clear sign of under-extraction.

To slow down the shot, grind your coffee finer, increase the dose, or tamp more firmly. These adjustments will give the water more time to extract the full flavors from the coffee.

At first, I rushed my shots, not realizing how much an extra few seconds could affect the flavor. Now, I always monitor the shot time to make sure it falls within the recommended range.

6. Fresh Coffee Matters

The freshness of your coffee beans can also impact extraction. Coffee loses its flavor over time, so even if you grind and brew perfectly, stale beans won’t yield a great shot.

I used to keep my coffee beans around for too long, not realizing the impact that freshness had on my espresso. Now, I use beans roasted within the past two weeks, and the difference is significant. Fresh beans contain more oils and soluble compounds, which lead to better extraction and richer flavor.

Conclusion: The Perfect Shot is Within Reach

Fixing under-extracted espresso is all about fine-tuning the variables—grind size, brew ratio, water temperature, tamp pressure, and shot time. It may feel overwhelming at first, but with practice, you’ll start to see how each adjustment influences the result. Don’t get discouraged by sour or thin shots—use them as learning experiences to refine your technique.

Through my own espresso journey, I’ve learned that small adjustments can make a big difference. By focusing on the details and practicing regularly, you’ll soon be pulling rich, balanced espresso shots that rival your favorite café.

Happy brewing!