Rather than follow standards blindly, you need to validate what really impacts your brew quality when deciding how coarse you should grind your coffee for French press.

Achieving the right profile in your cup is painstaking when you don't understand what truly influences flavor. 

Too often people battle weak, bitter or muddy coffee caused by using the wrong grind for their unique setup.

But have no fear—understanding how to tweak grind size based on your variables means finally gaining control.

In this article, we’ll help you solve your problems by explaining the important factors that affect extraction. You'll learn to challenge assumptions, diagnose issues in your cup, and precisely adjust grind to suit your tastes.

Armed with this knowledge, dialing in dark roast or light, hard or soft water becomes easy and ensures your French press delivers only balanced bliss with every brew.

The Short Answer

How coarse should you grind coffee for a French press? 

Most coffee experts will tell you to start with a medium-coarse grind for French press. 

That's slightly coarser than what you'd use for a drip coffee maker. Grinds at this size should feel gritty and grainy when rubbed between your fingers, like coarse sea salt. Try to avoid powdery grinds, as those can make your coffee bitter and sludgy.

So when grinding your beans, go a couple notches coarser than you normally would for another brew method.

Tip:
A burr grinder provides the most consistent grinds, 
minimizing fines that can make your coffee sour or gritty.

Now you've got a baseline to work from—we’ll explain more about how grind size impacts flavor.

How Grind Size Affects Flavor

The size of the grind affects how long hot water interacts with the coffee grounds and what compounds are extracted out. 

A coarser grind means less surface area for water to access and less contact time. This results in lower extraction, where less flavor-building acids and oils dissolve into your brew. You may get a weaker cup that is less bitter but also carries less grittiness.

On the other end, a very fine grind maximizes the surface area exposed to water. This promotes higher extraction, where more acids and oils dissolve over a shorter period. While it creates a stronger, more full-bodied cup, it also runs the risk of becoming overly bitter or harsh and silty—as the fine grounds will escape through the French press’s mesh filter.

The trick is balancing grind size to yield an extracted but clean cup. Too coarse and it’s weak— too fine and it crosses into bitterness. Aim for that equilibrium point where the coffee shines through but isn’t overwhelmed. Try adjusting incrementally to suit your taste.

Studies show grind size affects the rate at which different compounds are extracted from coffee grounds (Lui et al., 2023).  Finer sizes pull out more fast-dissolving flavors, sooner, compared to coarser grinds. This explains why changing grind can influence perceived acidity, body, and flavor profiles in the cup.

Dialing In Your Grind

(Coarse, Medium-Coarse, Medium grinds) 

Now that you know more about grind size's impact, here are some tips for honing in your settings:

• Start with a medium-coarse grind, slightly coarser than drip. Evaluate the flavor as a baseline.

• If the coffee tastes overly bitter or harsh, coarsen the grind slightly for lower extraction.  

Important Note: Keep in mind, all of the above assumes you are using standard suggested settings for other important variables—such as:

•  something close to a 1g to 15ml coffee-to-water ratio
•  a starting water temperature of around 200-205°F (94-96°C)
•  a brew time of around 4 minutes
  
  

It takes a little practice to zero in on the "Goldilocks zone" for your grind size preferences and setup. Don’t be afraid to adjust up or down fractionally to get the balanced cup you seek. 

Persistence pays off in finding that ideal grind size.

Your Setup Matters Too

No single grind setting is perfect for everyone, since individual factors come into play:

• Bean Type

Darker roasts have lower acidity and oils already developed during the roast. (Moon et al,. 2009) They often call for a touch finer grind to pull similar flavors from lighter roasted beans. For medium or light roasts, sometimes a couple notches coarser can prevent over-extraction.

• Water Chemistry

Hard water containing more dissolved minerals extracts compounds faster than soft water.  This is because minerals aid solubility. (Yoo et al,. 2020) When brewing with hard water, consider going a smidge coarser to adjust for this effect. For soft water, a standard medium-coarse grind often performs well.

• French Press Design

Wider mouth presses tend to let water flow and filter through more easily since the filter surface area is larger. Their construction is more forgiving of minor variations in grind size including slightly finer grinds.

Narrower presses may need the grind adjusted slightly coarser to prevent bitter, gritty cups. Start with a standard medium-coarse grind and tweak as needed based on your vessel.

• Personal Preferences

Some folks prefer a bolder, stronger cup. In that case, try grinding a whisper finer to coax out extra body and punch. Others like bright acidity balanced by creaminess. For their palates, a touch coarser keeps the brightness with less bitterness. Listen to your own taste and adjust accordingly.

• Keep Experimenting

With some experimentation, you'll learn how these factors influence your ideal grind size to make the “just right” cup of coffee brewed in your French press. Each variable is another tool for fine-tuning.

Grind Size References 

Here are common descriptions of different grind sizes to use as a reference:

• Coarse: Noteworthy chunks that feel gritty and chunky.
• Medium-coarse: Like coarse sand or gritty sea salt granules. Slightly finer than coarse.
• Medium: Feels similar to table or kosher salt between fingers.
• Fine: Approaching a smooth powder but still some granule feel. Between sand and powder. Usually not recommended for French Press.
• Very Fine: Nearly a powder without visible granule formation. Never recommended for French press. 

Example French Press Settings For Popular Grinders

Here are some specific grinder setting recommendations to use as a starting point:

Manual Grinder References

Electric Grinder References

Conclusion

Now that we’ve unpacked the intricacies of how grind size manifests in your French press, you have the insight and tools to finally unlock your brew's full potential.

We hope the guidance shared here equips you to tailor grind for balanced perfection. With some tweaking based on these principles, issues like bitterness or grit should become a thing of the past.

Most importantly, don't feel constrained by arbitrary standards—instead, trust your own taste buds to guide the journey of discovery.

Applying this information through exploration is sure to result in many enjoyable cups of coffee in the future. Now get out there and put your newfound wisdom to the test—the balanced bliss of perfectly dialed-in French press coffee awaits!

James

FAQ

How many times can you re-press the plunger when brewing?

Only press the plunger down once at the very end of brewing. Pressing multiple times can lead to over-extraction and release more sediment into the coffee. Let the coffee steep undisturbed until pressing at the end.

Can you use milk or creamers in French press coffee?

It's best to avoid adding milk, cream, or sweeteners to your French press when brewing coffee. Wait until after pouring your cup. Adding these to the press can block filtration and leave more sediment.

What's the best way to store leftover French press coffee?

Pour leftover coffee into an airtight container and refrigerate immediately. It will retain a decent flavor for 3-5 days. Avoid reheating more than once as reheating degrades flavor immensely.

References

Liu, Y., Chen, H., Zhu, Y., Li, Z., Chen, J., Liu, B., & Yang, G. (2023). Recent progress in black phosphorus and black-phosphorus-analogue materials: Properties, synthesis and applications. Progress in Materials Science, 123, 100822. https://doi.org/10.1016/j.pmatsci.2022.100822 https://www.sciencedirect.com/science/article/pii/S2772502223000719

Moon, J. K., Yoo, H. S., & Shibamoto, T. (2009). Role of roasting conditions in the level of chlorogenic acid content in coffee beans: correlation with coffee acidity. Journal of agricultural and food chemistry, 57(12), 5365-5369. https://doi.org/10.1021/jf900012b

Yoo, I. K., Jang, D. H., Kwon, W. J., Lee, K. H., & Lim, J. (2020). Effect of water hardness on coffee composition and coffee preference by university students. Korean Journal of Food Science and Technology, 52(5), 435-440. https://doi.org/10.9721/KJFST.2020.52.5.435