Grinding for Espresso: A Complete Guide

Espresso is the most demanding brewing method when it comes to grinding. The margin for error is razor-thin, and your grinder often matters more than your espresso machine. A mediocre grinder paired with a great machine will produce mediocre espresso. A great grinder paired with a mediocre machine can still produce excellent shots.

This guide covers everything you need to know about grinding for espresso, from understanding why it's so demanding to practical techniques for dialling in perfect shots.

Why Espresso Grinding is Different

Espresso brewing forces hot water through finely ground coffee at high pressure (typically 9 bars) for a short time (25-35 seconds). This creates unique demands on the grind:

Extreme Fineness

Espresso requires a much finer grind than any other brewing method except Turkish coffee. The particles must be small enough to create sufficient resistance for proper pressure to build, yet not so fine that water can't pass through at all.

Exceptional Consistency

Inconsistent particle sizes cause channeling—water finding paths of least resistance through the coffee puck. Channels create zones of over-extraction (bitter) and under-extraction (sour) in the same shot. The result is muddled, unbalanced espresso.

Precise Adjustability

Small grind changes dramatically affect shot time and taste. Espresso grinders need fine adjustment mechanisms to make micro-corrections, often achieved through stepless or stepped adjusters with many settings in the espresso range.

The Dialling-In Process

Dialling in is the process of adjusting your grind to achieve the desired shot. Here's a systematic approach:

Step 1: Set Your Parameters

Before adjusting grind, establish your baseline parameters:

• Dose: Start with 18-20g for a double shot (adjust based on your basket size)
• Yield: Aim for approximately 2:1 ratio (e.g., 36-40g output for 18-20g input)
• Time: Target 25-30 seconds from pump start to finish

Step 2: Make Your First Shot

Start with a grind setting in your grinder's espresso range (often quite fine). Weigh your dose carefully, distribute the grounds evenly, tamp consistently, and pull a shot while timing it.

Step 3: Evaluate and Adjust

The shot time tells you which direction to adjust:

Step 4: Taste and Fine-Tune

Once you're in the target time range, taste the espresso:

• Sour/acidic: May need slightly finer grind (more extraction)
• Bitter/harsh: May need slightly coarser grind (less extraction)
• Balanced sweetness with pleasant acidity: You've nailed it

Dosing and Consistency

Consistent dosing is as important as grind size. Variable doses produce variable shots, making it impossible to isolate grind adjustments.

Weigh Your Dose

Use a scale accurate to 0.1g. Weigh coffee into your portafilter (or a dosing cup) every time. Don't rely on timed dosing or volumetric measurements—these vary with grind size and bean density.

Single-Dosing vs Hopper

Single-dosing (weighing each dose individually) ensures freshness and precision. Grinders designed for single-dosing have low retention (minimal grounds left in the grinder between uses). Traditional hopper-fed grinders work well for cafes grinding constantly but can leave stale grounds that affect home users grinding infrequently.

Retention and Purging

Grinders retain varying amounts of coffee in the burr chamber. After adjusting grind settings, purge by grinding a few grams of beans to clear old grounds at the previous setting.

Distribution and Tamping

Even perfectly ground coffee won't extract well if it's unevenly distributed in the basket. Proper distribution and tamping create an even puck for uniform extraction.

Distribution Techniques

• WDT (Weiss Distribution Technique): Use thin needles or a WDT tool to stir grounds in the basket, breaking up clumps and distributing evenly.
• Distribution tools: Spinning levellers that create an even surface before tamping.
• Side-tapping: Gently tap the portafilter sides to settle grounds (can cause channeling if overdone).

Tamping

Tamp with consistent, level pressure—about 15-20kg of force is sufficient. The exact pressure matters less than consistency and levelness. An uneven tamp creates an uneven puck, causing channeling.

Signs of Grind Problems

Learn to read your shots to diagnose grind issues:

Channeling

Look for spurts, uneven flow, or bare spots on the basket bottom during extraction. These indicate water finding weak points in the puck. Causes include inconsistent grind, poor distribution, or uneven tamping.

Bottomless Portafilter Tells All

If you have a bottomless (naked) portafilter, use it for diagnosis. You can see exactly how extraction progresses—even flow converging to a single stream indicates good technique, while spraying or uneven streams indicate problems.

Blonde Early

If the shot turns blonde (pale) before reaching your target yield, extraction is happening too fast. Grind finer or check for channeling.

Excessive Crema

Some crema is desirable, but excessive crema can indicate under-extraction. The shot may taste sour beneath the crema.

Grinder Selection for Espresso

Not all grinders are suitable for espresso. Here's what to look for:

Adjustment Range and Precision

The grinder must adjust finely enough within the espresso range. Stepped grinders should have many steps in this zone; stepless grinders offer infinite adjustment.

Burr Quality and Size

Larger burrs (generally 58mm+) and quality steel produce more consistent particles. Smaller or cheaper burrs may create excessive fines (powder) that cause channeling.

Retention

For home use with infrequent grinding, low retention matters. Old grounds contaminating fresh ones affect taste and make dialling in difficult.

Build Quality

Espresso grinding is demanding. Cheap grinders may struggle with the fine settings required, producing heat and inconsistency. Quality construction ensures the grinder performs reliably over time.

Daily Adjustment

Espresso grind isn't set-and-forget. Plan to adjust regularly:

Bean Aging

Freshly roasted beans degas CO2 over time. As they age, you'll typically need to grind finer to maintain the same extraction. A shot that was perfect yesterday might need adjustment today.

Environmental Changes

Humidity and temperature affect both beans and grinding. On humid days, beans may grind finer; dry days may require adjustment in the opposite direction.

New Beans

Different beans require different grind settings. When you open a new bag or switch to a different coffee, expect to dial in again from scratch.

Common Mistakes to Avoid

• Chasing the perfect shot: Dial in until it tastes good, then stop. Endless adjustment is counterproductive.
• Changing multiple variables: Adjust one thing at a time. If you change grind and dose together, you won't know which affected the result.
• Ignoring distribution: Poor distribution can't be fixed by grind adjustment. Establish good technique first.
• Using stale beans: No amount of technique can save beans past their prime. Use coffee within 2-4 weeks of roasting.
• Blaming the machine: When shots taste bad, the grinder is usually the culprit. Check your grind before adjusting machine settings.

Practical Tips for Better Espresso

• Keep a log of your successful shots—dose, yield, time, grind setting, and any notes about the coffee.
• Start with well-reviewed recipes for your coffee and adjust from there.
• Use fresh beans from a quality roaster, ideally 1-3 weeks off roast.
• Invest in a good tamper and distribution tool—consistent technique matters.
• Be patient. Dialling in is a skill that improves with practice.