What is the best grind for cold brew?

When brewing cold brew, you are working with a massive contact time compared to traditional methods like drip or espresso. While a standard drip coffee might finish in five minutes, cold brew steeps for up to 24 hours. If you were to use a fine grind for this duration, the water would pull out too many bitter compounds and tannins, masking the sweet, chocolatey, and smooth notes that define a great cold brew.

In practice, the goal is to achieve a uniform, extra-coarse particle size. Using a high-quality burr grinder is the most effective way to ensure consistency. Blade grinders, by contrast, often create a mix of large chunks and fine 'dust.' These fine particles extract much faster than the larger ones, leading to a cloudy, gritty, and potentially harsh-tasting concentrate that is difficult to filter.

If you are using a home burr grinder, start at the coarsest setting and adjust based on your results. If your cold brew tastes thin or sour, you may need to move slightly finer; if it tastes bitter or is difficult to filter, go coarser. Remember that the texture should feel like coarse sea salt between your fingers.

Ultimately, the grind size is your primary tool for controlling the extraction rate in a low-temperature environment. By keeping the particles large, you ensure that the water interacts with the coffee slowly and evenly, resulting in a clean, refreshing, and balanced concentrate that highlights the inherent qualities of your chosen beans.