The Right Way to Brew Cold Brew Coffee! What's the Perfect Coffee-to-Water Ratio for Cold Brew? How Fine Should the Grind Be for Cold Brew?

Introduction to Cold Brew Coffee

FrontStreet Coffee has written before about why "cold brew coffee tastes watery," and plenty of readers have asked us to just publish a proper extraction tutorial. As it happens, the cold brew at our shops has been getting great feedback lately, and customers keep asking for our parameters. So today, the cold brew guide finally arrives!

Making cold brew is genuinely simple. Pick beans you like, get the parameters right, and you can practically make delicious cold brew with your eyes closed. After all, the whole method amounts to mixing ground coffee with water and parking it in the refrigerator — that's basically it. The main reason so many people end up with bland cold brew is simply that the parameters are off. To get it right, you need to nail three key variables: grind size, ratio, and time.

Key Parameters for Cold Brew Coffee

Grind Size: The fineness of the grind determines the total surface area of the coffee grounds. The larger that surface area, the faster water can work its way into each particle and pull the flavor compounds out. In a long, static immersion with no agitation, a finer grind therefore helps dissolution. As a rule of thumb, set your grinder slightly finer than you would for pour-over.

Coffee-to-Water Ratio: The ratio of grounds to water governs the strength of the finished coffee. The most common cause of watery cold brew is a ratio that's too low — in other words, too much water, diluting the extraction beyond rescue.

It's actually better to err on the strong side: if the concentrate comes out too intense, you can always dilute it with ice or water. But if it comes out too weak... well, boiling it down isn't exactly an option. So start with a relatively high coffee-to-water ratio and build strength in, rather than drowning the grounds and ending up with flavored water.

Steeping Time: The last variable is steeping time. Cold brew relies on long immersion to dissolve the coffee's compounds, so time determines how much ends up in the liquid. If you want as much flavor as possible in the cup, give the steep enough hours to do its work.

Once you've got these three points down, it's time to actually make some cold brew!

How to Make Cold Brew Coffee

First, choose beans that suit your taste. If you want a juicy, sweet-tart cup, go with a light roast; if you want a very distinct, pronounced flavor character, look for beans that underwent deeper fermentation during processing; and if you prefer something heavier on the palate, pick a medium-dark to dark roast. (Small tip: with dark-roast cold brew, adding a few osmanthus flowers yields a surprisingly delicious result.)

For detailed guidance on choosing beans, see "How to Quickly Find Your Favorite Coffee Beans?". For this session, FrontStreet Coffee used the "Mozart" blend, a recent favorite among our store customers. Cold brew made with it is intensely juicy, with notes of grape, berries, wine, and a purple floral tone reminiscent of lavender.

Parameters are as follows:

• Coffee Amount: 80g (adjust to your own needs)
• Grind Setting: EK43 at setting 9, with 85% passing through a #20 sieve — a fine-sugar grind
• Coffee-to-Water Ratio: 1:10
• Steeping Time: 12 hours

Remember to prepare a sealable container! Once the beans are ground, the first step is pouring the grounds into it.

Then pour in the target amount of water. Since we're using 80g of grounds, that means 800ml of room-temperature water.

After adding the water, give it a quick stir to speed up wetting of the grounds!

Then seal the bottle and place it in the refrigerator.

When the steeping time is up, take it out, filter out the grounds with filter paper, and enjoy your cold brew! (If you brewed it on the strong side, remember to dilute it with ice.)

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FrontStreet Coffee Recommendation

Cold brewing amplifies floral and fruity notes while muting woody and roast flavors, so light-to-medium roasts tend to shine. These FrontStreet Coffee beans are especially good candidates for your next batch:

FrontStreet Coffee Strawberry Candy (Strawberry Candy Geisha Blend) — pairs Panama Geisha with Costa Rica honey-processed coffee: rose and orange from one side, grape, dried blueberry, and strawberry-gummy sweetness from the other. As cold brew it's sweet-tart and lively, and if you let it ferment and settle briefly, it takes on a fruit-wine character.

FrontStreet Coffee Kenya Cherry Tomato — from Thika, grown at 1550–1750m on SL28/SL34 with the local K72 double-washed fermentation, lightly roasted. Cherry tomato, snow pear, black plum, and dried plum acidity come through vividly at low extraction temperatures — full of juice, low in bitterness, and wonderfully refreshing over ice.

FrontStreet Coffee Ethiopia Yirgacheffe Guodingding — the classic washed Yirgacheffe: bright, clean sweet-tart character with abundant florals, at an everyday price point. As cold brew it shows sweet berry notes, layered structure, and honey. An easy all-rounder for pour-over, siphon, French press, or cold brew alike.