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    by Loom Coffee Co. 3 min read

    A 1 lb to 1 gallon ratio with coarse-ground, naturally processed coffee steeped 18-24 hours in the fridge produces a rich, sweet cold brew concentrate you dilute 1:1 with water.

    Cold brew is the easiest method to execute and the hardest to get right if you pick the wrong coffee. Cold water can't extract the volatile acids that give bright, washed coffees their complexity. It extracts selectively, pulling smoother, sweeter, heavier compounds while leaving the high notes behind. Pick a coffee that plays to those strengths and the method takes care of itself.

    What do you need?

    • Large jar, pitcher, or French press carafe
    • Fine mesh strainer
    • Paper filter or cheesecloth (for second filtration)
    • Burr grinder
    • Kitchen scale (grams)
    • Kettle (for optional hot bloom)
    • 1 lb (454g) coffee, 1 gallon (3,785g) filtered water (for concentrate)

    What ratio and grind size should you start with?

    For concentrate, use a 1:1 ratio by weight: 1 lb of coffee to 1 gallon of water (454g to 3,785g). This is roughly 1:8.3 by weight. Dilute the finished concentrate 1:1 with water, and add a splash of cream if you like. Concentrate is the more versatile option because you control the final strength, and it stores more efficiently.

    Batch size Coffee Water
    Full batch 454g (1 lb) 3,785g (1 gallon)
    Half batch 227g ~1,890g
    Small batch 113g ~945g
    Ready-to-drink 75g 600g (1:8 ratio)

    Grind the same as French press: coarse, like kosher salt. Fine grounds in cold brew create two problems: the extra surface area produces an imbalanced extraction (harsh compounds dominate), and filtration becomes a mess. Coarse grounds extract more evenly over the long steep and filter cleanly.

    How long should you steep?

    Steep in the refrigerator for 18-24 hours for concentrate, or 14-16 hours for ready-to-drink. The flavor shifts meaningfully along the timeline:

    12 hours Light, sweet, underdeveloped
    14-16 hours Sweet spot for ready-to-drink
    18-24 hours Optimal for concentrate
    Past 24 hours Bitterness and astringency creep in

    Always steep in the refrigerator. We don't recommend room-temperature cold brew. Beyond the food safety concern (warm, protein-rich liquid sitting for 18+ hours is an environment for bacterial growth), fridge steeping is more forgiving. The cold slows extraction, giving you a wider window before bitterness sets in.

    Bonus: the hot bloom (our secret weapon)

    Cold brew made with only cold water can taste flat. It lacks the acidity that brings out dynamic flavors and contributes to the perception of sweetness. A short hot bloom before adding cold water fixes this.

    Pour about 500ml (roughly half a kettle) of 94°C / 202°F water over the grounds and stir to saturate. Let it bloom for 90 seconds. This brief hit of hot water degasses the coffee and extracts a small amount of the volatile acids that cold water alone can't reach. After 90 seconds, add the remaining cold filtered water, stir once more, cover, and refrigerate.

    The bloom ratio scales with your recipe: use roughly 13% of your total water volume as hot water. For a half batch (227g coffee, ~1,890g water), that's about 250ml hot. For a small batch (113g coffee, ~945g water), about 125ml.

    The result is a concentrate with more depth and brightness than a straight cold-water steep. You'll notice more flavor clarity and a sweeter finish.

    Which coffees should you use?

    Thrive in cold brew

    Naturally processed, chocolate-forward coffees with medium to medium-dark roast levels. Dominant flavor compounds (chocolate, nut, dried fruit, caramel) survive low-temperature extraction. Our Paubrasil Natural (hazelnut, chocolate malt, dried cherry) was built for this.

    Skip for cold brew

    Bright washed Ethiopians and light roasts. The volatile acids and delicate florals that make those coffees special don't extract well in cold water. Brew those hot, or flash-brew over ice to lock in the brightness.

    What should you adjust when the cup tastes off?

    Troubleshooting: taste adjustments
    • Thin and underdeveloped: Steep longer (add 2 hours). Or tighten your ratio slightly.
    • Bitter and harsh: You've overshot the steep time. Start tasting at 18 hours next batch. Past 24 hours, bitterness is almost guaranteed.
    • Silty or chalky: Your grind is too fine. Coarsen by 2-3 clicks, and double-filter (mesh strainer, then paper).

    Recipe: Cold Brew Concentrate

    • Coffee: 1 lb (454g)
    • Water: 1 gallon (3,785g) filtered
    • Ratio: 1:1 (1 lb per gallon)
    • Grind: Coarse (kosher salt, same as French press)
    • Method: Combine, stir to saturate, cover, refrigerate
    • Optional bloom: 500ml at 94°C / 202°F for 90 seconds before adding cold water
    • Steep: 18-24 hours in the fridge
    • Strain: Fine mesh, then paper filter
    • Dilute: 1:1 with water, splash of cream if desired
    • Storage: Sealed in fridge, 7-10 days

    Use 1 lb of coffee to 1 gallon of water (454g to 3,785g), which works out to roughly 1:8.3 by weight. Dilute the finished concentrate 1:1 with water or milk. For ready-to-drink cold brew you'll sip straight, use a 1:8 ratio (75g coffee to 600g water) instead.

    Steep concentrate for 18-24 hours in the refrigerator, or 14-16 hours for ready-to-drink. Flavor develops meaningfully along the timeline: body and sweetness peak around 14-16 hours for ready-to-drink, while concentrate needs the full 18-24 hours for complete development. Past 24 hours, bitterness and astringency start creeping in.

    Always steep in the refrigerator. Room-temperature cold brew creates a food safety concern because warm, protein-rich liquid sitting for 18+ hours is an environment for bacterial growth. Fridge steeping is also more forgiving because the cold slows extraction, giving you a wider window before bitterness sets in.

    Grind coarse, like kosher salt, the same setting you'd use for French press. Fine grounds create two problems in cold brew: the extra surface area produces an imbalanced extraction where harsh compounds dominate, and filtration becomes a mess. Coarse grounds extract more evenly over the long steep and filter cleanly.

    Naturally processed, chocolate-forward coffees with medium to medium-dark roast levels thrive in cold brew. Their dominant flavor compounds (chocolate, nut, dried fruit, caramel) survive low-temperature extraction. Skip bright washed Ethiopians and light roasts; the volatile acids and delicate florals that make those coffees special don't extract well in cold water.

    The hot bloom uses a short hit of hot water (about 13% of your total water volume at 94°C / 202°F) to degas the coffee and extract a small amount of volatile acids that cold water alone can't reach. Pour the hot water over the grounds, stir, wait 90 seconds, then add the remaining cold water and refrigerate. The result is a concentrate with more depth, brightness, and a sweeter finish.