Name: Cold Brew in a Jar: Easy Ready-to-Drink Recipe
Prep time: 10 min
Cook time: 8 h
Total time: 8 h 10 min
Ingredients: 80 g (2.8 oz) Coffee, ground medium-fine, Hario's recipe calls for dark roast; 1150 g (40.6 oz) Cold water, about 1,150 mL

Steps

Weigh 80 g of coffee and grind it medium-fine.

Put the coffee in a lidded jar or pitcher that holds at least 1.3 L, and pour in 1,150 g of cold water. Stir until every ground is wet.

Cover and refrigerate for about 8 hours.

Strain through a fine mesh strainer, then through a paper filter or clean cloth. Let it drain on its own.

Pour into a clean sealed bottle or jar and keep it in the fridge. Serve over ice; you should have about 1 L.

Ready-to-drink means brewed at drinking strength, so there is nothing to dilute: strain it and pour. It trades the concentrate’s flexibility for fewer steps, and it takes more fridge space per glass.

Where the numbers come from

Ratio, 1:14.4 by weight. This is the calculator’s default ready-to-drink ratio, taken from Hario’s published recipe for its Mizudashi pot: 80 g of coffee to about 1,150 mL of water for 1,000 mL brewed. That recipe is written for Hario’s mesh strainer; a jar plus a separate strainer uses the same ratio with a different filter.
Steep, 8 hours in the fridge. Hario’s figure for the same pot. A fridge brew runs slower than room temperature, and the studies we cite didn’t measure by how much; the steep time Lab file explains the gap.
Yield, about 990 mL. 1,150 − 2 × 80 = 990 mL at the calculator’s 2 g/g retention estimate. Hario says 1,000 mL.

For a bigger batch, use the scale link above; the calculator keeps the ratio and changes the weights.