Grind your fair-trade coffee coarse, about the texture of kosher salt or raw sugar, for cold brew. The National Coffee Association’s cold brew recipe uses a 12 to 24 hour steep, and a coarse grind keeps that long soak from turning bitter and muddy.
Fair-trade certification does not change the answer. Grind size depends on the brew method, not on how the beans were sourced, so the same coarse setting works for any fair-trade bean you buy.
The Short Answer: Coarse, Like Sea Salt
Coarse ground coffee is the standard starting point for cold brew across specialty coffee guidance. Stumptown Coffee Roasters and Blue Bottle Coffee both recommend a coarse grind for home cold brew, and they describe it the same way: think rough sea salt or raw sugar, much chunkier than drip or espresso grounds.
A coarse grind exposes less surface area to the water. Since cold brew steeps for 12 to 24 hours, that slower extraction keeps bitter and astringent flavors from taking over the cup.
Going finer, to a medium or espresso grind, over-extracts badly in a long cold soak. Blue Bottle’s guide warns that too fine a grind produces sediment and harsh flavors that are hard to strain out.
Use a Burr Grinder, Not a Blade
Even particle size matters more in cold brew than in fast brewing methods, because the grounds sit in water for up to a full day. A burr grinder crushes beans between two burrs into consistent coarse pieces.
A blade grinder chops beans at random, leaving a mix of large chunks and fine dust. Those fines slip through most filters and leave a cloudy, muddy cup.
Blade grinding also heats the beans unevenly, which can dull the delicate aromatics in a good single-origin fair-trade coffee.
- Burr type: conical or flat burrs, both produce even coarse grounds
- Grind setting: coarse, tuned to texture of kosher salt or raw sugar
- Best practice: grind right before brewing, never days ahead
Ratios and Steep Times
Use the table below to choose your cold brew ratio and steep time based on how you plan to drink it.
| Cold Brew Style | Ratio (Coffee to Water) | Steep Time |
| Concentrate, room temperature | 1:4 (e.g., 1 cup coffee to 4 cups water) | 12 to 24 hours, then strain and dilute |
| Ready-to-drink concentrate | 1:8 for a milder batch | 12 to 16 hours at room temperature |
| Refrigerated steep | 1:4 to 1:5 | 18 to 24 hours, chilled from start to finish |
| Single-serve test batch | 25 g coffee to 200 g water | Start at 12 hours, taste at intervals |
The National Coffee Association’s cold brew recipe uses 1 cup of ground coffee to 4 cups of water as a concentrate, with dilution to taste after straining. Steep in the refrigerator or at room temperature for 12 to 24 hours.
Warmer water is not part of cold brew, but room temperature steeps extract slightly faster than refrigerated ones, so a chilled 18 to 24 hour steep roughly matches a 12 to 16 hour room temperature steep.
Adjust by Roast Level
Fair-trade certified coffees are often high-grade, single-origin specialty beans, and roast level changes how fast they extract. Perfect Daily Grind notes that grinding high-grade beans too finely strips away their origin-specific floral and fruit notes with generic bitterness, so grind size is really a flavor-preservation decision for these coffees.
Light to medium roasts hold onto their delicate acidity and aromatics. A standard coarse grind with a longer steep, closer to 18 to 24 hours, gives sweet water enough time to pull those compounds out.
Dark roasted fair-trade beans are more porous and dissolve faster, with roasty, chocolate-leaning flavors. An extra-coarse grind with a shorter steep, around 12 to 16 hours and preferably chilled, prevents smoky over-extraction.
This is the one place where a slightly finer grind helps in cold brew: very light roasts sometimes taste thin at a full extra-coarse setting, so if your brew tastes watery, nudge the grind slightly finer and steep longer rather than jumping settings.
Troubleshooting by Taste
Bitter, harsh, or sludgy cold brew can indicate too fine a grind or too long a steep. Move one small step coarser or shorten the soak, and strain through a paper filter for a cleaner cup.
Weak or watery brew can indicate the opposite problem. Grind slightly finer, extend the steep toward 24 hours, or raise your dose rather than changing multiple things at once.
Coffee science research summarized by Barista Hustle explains the mechanism behind this: cold water is a weak solvent, so extraction depends almost entirely on contact time rather than heat, which is why grind size and steep time do the work that temperature does in hot brewing.
Freshness affects this troubleshooting too. Stale grounds behave differently than fresh ones, and if your beans have been sitting around for a while, check how fresh fair-trade coffee should be for cold brew before blaming the grind.
Filtered, Then Filtered Again
Strain the finished brew through a stainless-steel sieve first to catch the bulk of the grounds. Then run it a second time through a paper filter or fine cloth to remove residual sediment.
Suspended fine particles keep extracting in the fridge, so a clean second pass keeps your batch from turning bitter during storage, even days later.
Cold brew keeps for up to two weeks refrigerated, and a well-filtered batch tastes consistent on day ten, which is something hot brewed coffee cannot match.
If you also brew hot methods with your fair-trade beans, remember that each method has its own grind answer. Espresso needs a fine grind and high pressure, Turkish coffee needs a powder-fine grind, and that is a completely different game from cold brew.
Why Grind Size Carries So Much Weight Here
In hot brewing, temperature drives extraction and speed hides grind imperfections. In cold water, none of that thermal energy exists, so particle size becomes the main dial you control.
Roast level shifts solubility, and steep length shifts contact time, but grind size sets how much of each particle the water can reach at all. That combination, grind plus time plus temperature acting together, is why a coarse grind with a long steep produces sweet, smooth coffee while a fine grind with the same steep turns harsh.
Stumptown’s guide reaches the same conclusion from the practical side: start coarse, taste, and only adjust if the cup tells you to.
For contrast, if you ever make fair-trade coffee in a drip machine, that method uses a medium grind with contact times of four to eight minutes, and that difference in contact time alone explains why the two settings are nothing alike.
Pair your brew with a cold brew maker with a fine mesh filter to make straining simple. A digital scale also makes your 1:4 or 1:8 ratio repeatable batch after batch.
Conclusion
Grind fair-trade coffee coarse, like kosher salt, for cold brew. Steep 12 to 24 hours at a 1:4 concentrate ratio, then strain twice and dilute to taste. Start with one test batch tonight, taste it before adjusting anything, and let the cup tell you whether to go coarser or finer.