calculators.coffee by Timberline Coffee School

Cold Brew Calculator

Dose, water, and steep time for cold brew concentrate or ready-to-drink. 1:5 concentrate default.

Brew a concentrate (default 1:5, range 1:4 to 1:8). Dilute at service with water or milk.

1 :

Default 1:1 (equal parts concentrate and water or milk at service).

Prep Steps

  1. 1

    Combine

    Add grounds to your container; pour cold or room-temperature water over the grounds to reach target weight. No heat needed.

  2. 2

    Stir

    Stir thoroughly to ensure all grounds are saturated; dry clumps on top will not extract.

  3. 3

    Seal and Refrigerate

    Cover tightly; refrigerate for your target steep time. Room-temperature steeping is faster but increases fermentation risk for long steeps.

  4. 4

    Strain

    Filter through a fine mesh or paper filter into a clean vessel; do not press or squeeze grounds (this adds bitterness).

  5. 5

    Dilute and Serve

    Add water or milk to taste at the ratio you set above (default 1:1 concentrate to water). Pour over ice.

Last updated

How to Use This Calculator

  1. Choose Concentrate or Ready-to-Drink

    Concentrate mode (default) uses a 1:5 ratio; dilute at service with water or milk to taste. Ready-to-drink mode (default 1:12) brews at serving strength. Pour straight over ice.

  2. Enter Dose and Water

    Type your coffee dose in grams (or ounces) and your brew water amount. Cold brew is typically made in larger batches; 100 g of coffee to 800 g of water is a practical starting point.

  3. Set Steep Time

    The default is 16 hours in the refrigerator. Adjust from 8 to 36 hours based on preference. Longer steeps extract more at low temperature without the bitterness you get from heat.

  4. Read the Result

    The result card shows concentrate yield, diluted serving yield (in concentrate mode), number of cups, and the steep advisory. Copy the recipe to keep it handy.

Cold Brew: Ratio and Time

Cold brew comes down to two variables: ratio and time. Coarse grind, cold water, 16 hours in the refrigerator. Rushing the steep or moving it to room temperature to speed things up produces a noticeably different result.

The SCA’s cold brew standard sets the steep temperature at 35  °C or below. Refrigerator temperature (2–4 °C) is slower but produces the cleanest, sweetest extraction. The low temperature suppresses the bitter and astringent compounds that extract faster at ambient. If you need cold brew today and you steep at room temperature, use 8–10 hours max and taste-test; the margin for over-extraction narrows significantly.

The concentrate default here (1:5) brews a strong batch meant to be diluted at service. At 100 g of coffee and 500 g of water you get roughly 450 mL of concentrate. Diluted 1:1 that gives about 900 mL of serving-strength cold brew, or three to four cups at 240 mL each. Increase the water to 1:8 (800 g) for a larger, lighter batch if you prefer.

Strain thoroughly. Paper filter over a fine-mesh strainer gives the cleanest result. Unfiltered cold brew develops silt that gets more noticeable as it sits in the fridge. Finished cold brew keeps for 7–10 days refrigerated; concentrate keeps longer than ready-to-drink because the dilution happens at service.

Grind, Temperature, and Timing

Grind coarse: coarser than French press, which itself is already coarse. You have 16 hours to extract; fine grinds will over-extract and go bitter. A coarse, even grind through a burr grinder is the right call. Blade-grinder cold brew tends to be muddy and uneven regardless of steep time.

If you want ready-to-drink cold brew, use 1:10 to 1:14 and skip the dilution step. The distinction matters for batch planning: a 1:5 concentrate takes less fridge space and dilutes fresh at each serving, while a 1:12 ready-to-drink batch is larger but needs no preparation at service.

ParameterRecommendationNotes
Ratio (concentrate)1:5 (default)Dilute at service with water or milk. Range 1:4 to 1:8.
Ratio (ready-to-drink)1:12 (default)Brew at serving strength; no dilution needed. Range 1:10 to 1:14.
Grind sizeCoarseCoarser than French press. Even grind from a burr grinder.
Steep temperature2-4 °C (35-39 °F)Refrigerator temperature. Suppresses bitter extraction.
Steep time12-24 hours16 hours is a reliable default. Taste and adjust.
Shelf life7-10 daysRefrigerated in a sealed container. Strain before storing.

Frequently Asked Questions

What is the best ratio for cold brew coffee?

For a concentrate meant to be diluted at service, 1:8 is the coffee-shop standard: 100 g of coffee to 800 g of cold water. That gives you roughly 700 mL of concentrate, which dilutes 1:1 to about 1.4 L of serving-strength cold brew at an effective 1:16 ratio. If you want ready-to-drink cold brew without dilution, use 1:14 to 1:16 directly.

How long should I steep cold brew?

12 to 24 hours in the refrigerator is the standard range. 16 hours is a reliable starting point for most coarse grinds. Steeping at refrigerator temperature (2-4 °C) is slower than room temperature but produces a cleaner, sweeter cup because the low temperature suppresses bitter and astringent compounds. If you steep at room temperature to speed things up, reduce to 8 to 10 hours and taste-check frequently.

What grind size should I use for cold brew?

Coarse: coarser than French press. You have 16 hours to extract, so fine grinds will over-extract and go bitter. A burr grinder on its coarsest or near-coarsest setting is the right call. Blade-grinder cold brew tends to be muddy and uneven regardless of steep time because the uneven particle distribution means fine dust over-extracts while larger chunks under-extract.

What is the difference between cold brew concentrate and ready-to-drink cold brew?

Concentrate is brewed at a high ratio (1:4 to 1:8) and diluted 1:1 at service with water or milk, giving a final drinking ratio around 1:16. Ready-to-drink (RTD) is brewed at serving strength (1:14 to 1:16) and poured straight over ice with no dilution step. Concentrate keeps longer in the fridge because you're storing a smaller volume, and dilution happens fresh at each serving.

How long does cold brew last in the refrigerator?

Finished cold brew keeps for 7 to 10 days refrigerated. Concentrate keeps toward the longer end of that range because the dilution step happens at service. Ready-to-drink cold brew is best within 7 days. Always store in a sealed container and strain thoroughly before refrigerating. Silt left in the brew will continue to extract and turn the coffee bitter faster.

Timberline Coffee School

Trent built this calculator. He also runs Timberline Coffee School, where baristas and roasters train through SCA-accredited programs covering espresso, brew method, and sensory skills.

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