Ever pulled an espresso shot that tasted sour, bitter, or just… off? You’re not alone. For most home baristas, the culprit is almost always the same: grind size. Getting it right can feel like chasing a moving target, but once you understand the basics, dialing in becomes a straightforward process rather than a frustrating guessing game.
If you’ve been struggling to get consistent, delicious espresso from your home setup, this guide will walk you through exactly how to dial in your grind size step by step. By the end, you’ll know how to read your shots, make adjustments, and finally pull espresso you’re proud of.
Why Grind Size Matters for Espresso
Espresso is all about extraction—the process of water pulling flavors, oils, and compounds out of your coffee grounds. Grind size directly controls how quickly or slowly this happens. Think of it like this: finer grounds have more surface area, so water extracts flavor faster. Coarser grounds slow things down.
When your grind is too fine, water struggles to pass through the coffee puck. The result? Over-extraction. Your shot runs too slowly, and you end up with bitter, harsh, or burnt-tasting espresso. On the flip side, when your grind is too coarse, water rushes through too quickly. This causes under-extraction, leaving you with a sour, weak, or watery shot.
The goal is to find that sweet spot where water flows through at the right pace, extracting balanced flavors. For most espresso setups, you’re aiming for a shot time of roughly 25–35 seconds for a standard double shot (about 36 grams of liquid from 18 grams of coffee). These numbers aren’t set in stone, but they give you a reliable starting point.
What You Need Before You Start
Before you begin dialing in, make sure you have a few essentials ready:
- A burr grinder with adjustable settings – Blade grinders won’t give you the consistency you need for espresso. Even an entry-level burr grinder makes a huge difference.
- A digital scale – Measuring by weight (not volume) is crucial for repeatability. Look for one that measures to 0.1 grams.
- A timer – Most espresso machines have a built-in timer, but your phone works fine too.
- Fresh coffee beans – Ideally roasted within the last 2–4 weeks. Stale beans behave unpredictably and make dialing in harder.
- A notebook or notes app – Tracking your adjustments helps you learn faster and avoid repeating mistakes.
Once you have these basics covered, you’re ready to start experimenting.
Step-by-Step Guide to Dialing In Your Grind Size
Here’s a simple, repeatable process you can follow every time you open a new bag of beans or notice your shots drifting off target.
Step 1: Start with a Baseline
Set your grinder to a medium-fine setting. If your grinder has numbered settings, start somewhere in the middle of the espresso range. Dose 18 grams of coffee into your portafilter, distribute evenly, and tamp with consistent pressure.
Step 2: Pull Your First Shot
Start your shot and timer simultaneously. Watch the espresso as it flows. You’re looking for a steady stream that starts after a few seconds of pre-infusion. Stop the shot when you reach about 36 grams of liquid in your cup (a 1:2 ratio). Note the total time.
Step 3: Evaluate the Results
Now assess what happened:
- Shot finished in under 20 seconds? Your grind is too coarse. The water passed through too quickly.
- Shot took longer than 35 seconds? Your grind is too fine. Water struggled to get through.
- Shot landed between 25–35 seconds? You’re in the ballpark. Time to taste.
Step 4: Taste and Adjust
Timing alone doesn’t tell the whole story. Taste your shot:
- Sour, acidic, or thin? This signals under-extraction. Try grinding finer.
- Bitter, ashy, or harsh? This points to over-extraction. Try grinding coarser.
- Balanced, sweet, with pleasant acidity? You’ve found your target. Write down your settings.
In short: let your taste buds guide you, not just the clock.
Step 5: Make Small Adjustments
When adjusting your grinder, move in small increments. On most grinders, one or two notches (or a few degrees of rotation) is enough. Large jumps make it harder to zero in on the right setting. After each adjustment, purge a small amount of coffee to clear any grounds stuck at the old setting, then pull another shot.
Step 6: Repeat Until Dialed In
Keep repeating steps 2–5 until your shot tastes balanced and falls within your target time range. This might take 3–5 shots, sometimes more with a new coffee. Don’t get discouraged—this is completely normal, even for experienced baristas.
Common Mistakes Beginners Make (and How to Avoid Them)
Dialing in has a learning curve. Here are some pitfalls to watch out for:
- Changing too many variables at once – If you adjust grind size, dose, and tamp pressure all at the same time, you won’t know what actually fixed (or broke) your shot. Change one thing at a time.
- Ignoring distribution – Uneven grounds in your portafilter cause channeling, where water finds the path of least resistance and over-extracts some areas while under-extracting others. Use a distribution tool or simply tap and level the grounds before tamping.
- Using stale beans – Old coffee loses CO2 and becomes harder to extract properly. If your shots suddenly taste flat or you can’t seem to dial in, check your roast date.
- Not purging after adjustments – Leftover grounds from your previous setting can throw off your next shot. Always run a few grams through after changing the grind.
- Expecting perfection immediately – Even professionals spend time dialing in new coffees. Give yourself grace and treat each shot as a learning opportunity.
Frequently Asked Questions
How often do I need to adjust my grind size?
You’ll typically need to re-dial whenever you open a new bag of beans, switch to a different coffee, or notice your shots drifting over time. Coffee changes as it ages, so minor tweaks every few days are normal.
What if my shot tastes both sour and bitter?
This usually indicates channeling—water is flowing unevenly through the puck. Focus on improving your distribution and tamping technique before adjusting grind size. A bottomless portafilter can help you spot channeling visually.
Does the dose affect grind size?
Yes. If you increase your dose (say, from 18g to 20g), you’ll likely need to grind slightly coarser to maintain similar shot times. The two variables are connected, so keep your dose consistent while dialing in.
Can I use pre-ground coffee for espresso?
Pre-ground coffee is almost always too coarse or too stale for proper espresso. Grinding fresh right before brewing gives you control over the grind size and dramatically improves flavor.
Why do my shots taste different in the morning vs. evening?
Humidity and temperature changes throughout the day can affect how coffee behaves. Many home baristas notice they need to grind slightly finer in humid conditions. Small daily adjustments are part of the process.
Final Thoughts and Next Steps
Dialing in your grind size might seem intimidating at first, but it quickly becomes second nature. The key is to approach it systematically: pull a shot, evaluate the time and taste, make a small adjustment, and repeat. Keep notes, stay patient, and trust your palate.
Once you get comfortable with this process, you’ll start noticing subtle differences between coffees and developing your own preferences. That’s when home espresso gets really fun. So grab your grinder, weigh out some fresh beans, and start experimenting—your best shot is just a few adjustments away.
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