Chemex Grind Size: Best Settings, Brew Tips & Grinder Comparisons

Quick Answer

The best grind size for Chemex is medium-coarse, similar to sea salt. For a clean, balanced brew, use a 1:16 coffee-to-water ratio, with a total brew time of 4 to 4.5 minutes. Set your burr grinder to 18–20 on Baratza Encore or match it visually to rough sand. Avoid blade grinders for consistency. Adjust grind finer or coarser to fix sour or bitter flavors.

Key Takeaways

• Use a medium-coarse grind for Chemex brewing.
  
• Burr grinders provide the most consistent results.
  
• Blade grinders cause uneven extraction.
  
• Adjust grind size to control sour or bitter notes.
  
• Ideal brew time is 4–4.5 minutes.
  
• Grinder settings vary by brand—use visual guides.
  

Imagine buying fresh organic coffee and brewing it in your stylish Chemex—only to taste something off. You followed the recipe, but the result was sour or bitter. We've all been there. 

But the real issue is not your water or beans but it's your grind size. As one coffee expert put it, "The backbone of great coffee = the perfect coffee grounds." Let's break down how the right grind can transform your Chemex experience.

What's the Best Grind Size for Chemex Coffee?

When brewing with a Chemex, you need a medium-coarse grind size. It's similar to sea salt or rough sand in texture. This specific grind size balances two critical factors: proper extraction and flow rate. According to Araku Coffee, "When using a Chemex, it is recommended to use a medium grind, similar to cane sugar. A grind that is too fine may clog the paper filter, a grind that is too coarse can result in a coffee lacking flavor".

Medium-coarse grounds allow water to pass through at the right speed. Too fine, and your coffee becomes over-extracted and bitter because the water moves too slowly. Too coarse, and you get under-extracted, weak coffee because the water rushes through too quickly.

The Chemex filter is significantly thicker than other pour-over filters. This thickness requires a slightly coarser grind than what you'd use for methods like the V60. The unique filter design creates that clean, bright cup Chemex is famous for by trapping more oils and fine particles.

How Grind Size Affects Chemex Extraction

Coffee extraction sounds complicated but breaks down simply: it's about getting the good stuff out of your coffee beans and into your cup. The grind size determines how quickly flavors extract.

Think of coffee grounds like sugar cubes. A large cube dissolves slower than granulated sugar. The same happens with coffee—coarser grinds extract slower because they have less surface area exposed to water.

When your Chemex coffee tastes sour or acidic, that's under-extraction—your grind is too coarse. The water passed through too quickly without grabbing enough flavor compounds. But when it tastes bitter or hollow, that's over-extraction—your grind is too fine, and too many bitter compounds get pulled out.

A recent study published in the journal Chemosensors confirms this relationship: "Our findings demonstrate that finer grind sizes significantly affect TDS and E, roast level and grind size significantly affect sensory attributes, as measured by the taste sensing system".

Here's a simple guide to adjust your brew:

Why Burr Grinders Outperform Blade Grinders

Ever wonder why coffee shops use those big, expensive grinders? It's all about consistency. Blade grinders chop beans randomly and create a mix of coffee dust and chunks. This inconsistency means some grounds over-extract (creating bitterness) and others under-extract (creating sourness) in the same cup.

Burr grinders crush beans between two burrs set at a precise distance. This creates uniform grounds—the secret to even extraction and balanced flavor. Plus, burr grinders generate less heat and preserve more aromatics and flavors.

As Golden Cava Coffee explains, "If you choose a grind size that's too fine, your coffee may become over-extracted and bitter due to increased surface area exposure and slower flow rates caused by clogged filter papers in Chemex brewer".

Manual burr grinders (hand-cranked) offer excellent quality at lower prices. Electric burr grinders save time and effort but cost more. Both outperform blade grinders dramatically for Chemex brewing.

Popular Burr Grinder Settings for Chemex

Different grinders use different numbering systems. It makes it confusing to know which setting works best. Here's a quick reference for popular models:

Remember—no two grinders are exactly the same due to calibration differences. Use these settings as starting points, then adjust based on your taste preferences.

You can also use visual cues: your ground coffee should look like rough sand or sea salt. Too powdery? It's too fine. Looks like chunky pebbles. Too coarse.

Recent research from the University of Mahasarakham showed that "the crude extract yield increased as the particle size decreased," but interestingly, yields decline when particles become too fine—similar to what happens with coffee extraction.

How to Adjust Grind Size Based on Taste

Your taste buds tell you everything you need to know about your grind size. Here's how to listen:

If your coffee tastes sour, sharp, or acidic:

• Your grind is too coarse
  
• Water passed through too quickly
  
• Solution: Use a finer grind next time
  

If your coffee tastes bitter, hollow, or lacks flavor:

• Your grind is too fine
  
• Water passed through too slowly
  
• Solution: Use a coarser grind next time

Your brew time also offers clues. The ideal Chemex brew takes 4 to 4.5 minutes. If your coffee drains in under 3 minutes, your grind is too coarse. If it takes over 5 minutes, your grind is too fine.

Temperature matters too. Hotter water extracts faster, so you might need a slightly coarser grind with near-boiling water.

Step-by-Step Chemex Brew Guide

Let's put all this knowledge into practice with a foolproof Chemex brewing guide:

You'll need:

• 30g coffee (medium-coarse grind)
  
• 480ml filtered water (1:16 ratio)
  
• Chemex brewer
  
• Chemex filter
  
• Gooseneck kettle
  
• Scale with timer
  

Instructions:

1. Heat water to 93°C (200°F)

Boil water, then let it sit for 30 seconds.

2. Prep your filter

Place the filter in the Chemex with the triple-fold side against the spout. Rinse with hot water to remove paper taste and preheat the Chemex. Discard rinse water.

3. Add coffee grounds

Add your medium-coarse ground coffee and level the bed.

4. Start the bloom

Start your timer. Pour just enough water (about 60g or twice the coffee weight) to saturate all grounds. Let it bloom for 30-45 seconds.

5. First pour (0:45)

Slowly pour water in spirals until you reach about 240g total water weight.

6. Second pour (1:30)

Add water up to 360g total.

7. Final pour (2:15)

Add remaining water to reach 480g total.

8. Let it drain (3:00-4:30)

Allow all water to drain through. Total brew time should be around 4-4.5 minutes.

9. Serve and enjoy

Remove the filter, swirl the coffee, and serve.

Research from Scientific Reports confirms the importance of proper brewing parameters: "The extraction rate and yield increased with increasing brewing temperature and decreasing grind size. Brew ratio significantly affected the extraction yield and titratable acidity of the brews".

Chemex Troubleshooting Tips

Even experienced baristas run into issues. Here are some common Chemex problems and fixes:

Brew taking too long (over 5 minutes):

• Your grind is too fine
  
• Solution: Use a coarser grind next time
  

Brew finishing too quickly (under 3 minutes):

• Your grind is too coarse
  
• Solution: Use a finer grind next time
  

Filter collapsing into the spout:

• The triple-fold side of the filter isn't positioned correctly
  
• Solution: Place the thicker, folded part against the pouring spout

Weak or astringent coffee:

• Under-extraction due to coarse grind or low dose
  
• Solution: Use a finer grind or increase coffee amount

Coffee tastes flat or lacks brightness:

• Water temperature too low
  
• Solution: Use water closer to 200°F (93°C)

A study in Scientific Reports found that "cold brew had lighter color and lower titratable acidity than hot brew," which explains why grind size adjustments might differ between brewing methods.

Chemex vs Other Brew Methods (Grind Size Comparison)

Different brewing methods require different grind sizes. Here's how Chemex compares:

The Chemex requires more precision than some methods because of its unique filter and brewing dynamic. The thick paper creates resistance, but not as much as an espresso machine's pressure.

Conclusion

Grind size plays a crucial role in Chemex brewing success. The James Hoffmann YouTube channel demonstrates this brilliantly in his video on grind consistency. Remember that each grinder calibrates differently—start with our recommendations, then adjust based on taste.

According to brewing experts, "The way your coffee tastes is the ultimate arbiter of grinding success." Trust your palate above all else when dialing in your perfect Chemex grind.

If you are ready to taste the difference proper grinding makes then try Lifeboost's organic, shade-grown coffee beans with your Chemex. Our low-acid and single-origin beans reveal stunning clarity and flavor notes when brewed at medium-coarse grind.

Frequently Asked Questions (FAQ)

Can I use a blade grinder for Chemex?

It's not recommended. Blade grinders create uneven grounds and so leading to poor extraction and off flavors.

What setting should I use on a Baratza Encore for Chemex?

Between 18–20 is ideal for medium-coarse grind.

What does under-extracted Chemex coffee taste like?

Sour, acidic, or salty—often due to grind being too coarse.

What does over-extracted Chemex coffee taste like?

Bitter and hollow with muted flavors.

Can I use pre-ground coffee for Chemex?

You can, but it's not ideal. Freshly ground beans using a burr grinder yield better results.

About the Author

This article was written by the Lifeboost writing team based on current coffee research from multiple peer-reviewed sources. We referenced information from trusted coffee experts and scientific studies to ensure accuracy and practical value.

Disclaimer: The information in this article is for educational purposes only. Individual results may vary based on coffee beans, water quality, and brewing equipment. Always refer to your specific grinder's manual for recommended settings.

Check out Lifeboost Coffee Grata Medium Roast.