How to Make Cold Brew Concentrate Like a Pro: Ratios, Timing, and Storage

Quick Answer: Your Go-To Cold Brew Concentrate Recipe

For a balanced concentrate, use a 1:4 coffee-to-water ratio (by weight) and steep for 18–24 hours at room temperature. Filter with a paper filter for a cleaner cup, then store in the fridge for up to two weeks. Adjust to taste, but this starting point works for most.

Cold brew concentrate is the secret to café-style iced coffee at home—smooth, low-acid, and endlessly versatile. Unlike regular cold brew, a concentrate is brewed stronger and then diluted with water or milk, giving you more control over each cup. To make a great concentrate, you need the right ratio, the right time, and the right storage method.

This guide walks you through the entire process, from choosing your beans to brewing and storing. You'll learn the golden ratio, the ideal brewing window, and how to keep your concentrate fresh for longer. Whether you're new to cold brew or looking to refine your technique, these steps will help you brew like a pro.

Choose the Right Coffee Beans and Grind Size

The coffee you start with defines your cold brew. Look for beans with chocolate, nutty, or caramel notes—these hold up beautifully in cold extraction. A coffee like Stumptown's Indonesia Bies Penantan brings a rich, full-bodied flavor with notes of dark chocolate and toasted nuts, making it an ideal base for concentrate. Dark and medium roasts generally yield a bolder, sweeter concentrate, while lighter roasts can produce more floral and fruity tones.

Grind size matters too. Use a coarse grind, similar to breadcrumbs or sea salt. Too fine, and your cold brew will be cloudy and over-extracted, with bitter notes. Too coarse, and you'll leave flavor behind. If you're buying pre-ground, ask for a coarse grind; at home, a burr grinder like the J Scale 4000—which doubles as a precise scale—helps you dial in the right dose.

• Coarse grind: aim for particles about the size of coarse sand.
• Medium-dark roast: brings natural sweetness and low acidity.

Master the Ratio: Use 1:4 for Concentrate

The ratio of coffee to water is the most important variable in cold brew. For a concentrate, use 1 part coffee to 4 parts water by weight. For example, 100 grams of coffee to 400 grams of water yields a strong base you can dilute to taste. Use a digital scale for accuracy—the J Scale 4000 is a reliable, budget-friendly option that ensures consistent results. Different coffees have different densities, so weighing beats measuring by volume.

A 1:4 ratio is a versatile starting point. If you prefer a slightly milder concentrate, try 1:5. If you like it intense, go 1:3. Just be aware that stronger ratios extract more quickly, making the brewing time more sensitive. Keep a notebook or note app handy to track what works for your preferred cup.

• Weigh your coffee and water in grams for consistency.
• Adjust the ratio gradually—don't jump from 1:4 to 1:3 all at once.

Steep for the Perfect Time: 18–24 Hours

Time and temperature are your extraction controls. Steep at room temperature for 18–24 hours. This window yields a smooth, concentrated brew with balanced sweetness and chocolatey depth. Less than 16 hours often tastes weak and sour; more than 24 hours can turn bitter and grassy. The sweet spot is around 20 hours for most roasts.

But time isn't one-size-fits-all. A darker roast like Stumptown's French Roast may extract faster, so you might find 18 hours ideal. A lighter roast might need the full 24. Start at 20 hours and adjust based on taste. Use a timer and taste a spoonful at each interval to learn your preference. A paper filter, like the OXO Cold Brew Coffee Paper Filters, adds a clarifying step after steeping, reducing sediment and giving a cleaner cup.

• Steep at room temperature—not in the fridge—to extract profile you want.
• Taste-test at 18, 20, and 24 hours to find your perfect window.

Filter Twice for a Clean, Clear Concentrate

Filtration is a step many home brewers skip, but it's the difference between a brilliant concentrate and a muddy one. Start with a fine-mesh strainer to remove the bulk of the grounds, then pass the liquid through a paper filter or a clean cheesecloth. The paper filter catches fine particles that cause cloudiness and contribute to off-flavors over time.

You have several filter options depending on your gear. The OXO Cold Brew Coffee Paper Filters are designed for the OXO Compact Cold Brew Coffee Maker, providing an extra layer that yields a distinctly cleaner extraction. If you're using a French press or a cold brew bag, a paper filter step is still worth the effort. The Origami Filters, Medium, work well for smaller batches and pour-over-style filtration. Whatever you use, aim for a clear liquid—cloudiness isn't a flavor defect, but it can become bitter as the concentrate ages.

• Use a paper filter for the final pass—it makes a visible difference.
• Filter while the concentrate is cold to reduce extraction from fine grounds.

Store Properly to Maximize Freshness

Cold brew concentrate is highly perishable once brewed. Store it in an airtight glass jar in the refrigerator, and it will stay fresh for up to two weeks. But oxidation slowly degrades flavor—after day seven, you may notice duller taste. For the best quality, consume within the first week, and always keep the container sealed when not in use.

Avoid keeping concentrate at room temperature; this accelerates microbial growth and flavor loss. If you've made a big batch, consider freezing it in ice cube trays for convenient, single-shot portions. These cubes thaw quickly and are great for fractional use. Also, don't add milk or sugar to the main batch—keep the concentrate pure and add flavor per cup for maximum shelf life.

• Use glass over plastic—it doesn't absorb odors.
• Label your container with the brew date to track freshness.

Cold Brew Concentrate, Step by Step

1. Grind your coffee coarse: Grind 1 part coffee beans (e.g., 100g) to a coarse consistency—like sea salt. Use a burr grinder if you have one. Too fine a grind leads to muddy, bitter concentrate.
2. Weigh 4 parts water: Weigh out 400g of cold, filtered water for every 100g of coffee. Pour over the grounds and stir gently to saturate all particles. Stirring ensures even extraction and prevents dry pockets.
3. Steep for 18–24 hours: Cover and leave at room temperature. Taste at 18, 20, and 24 hours to find your sweet spot. Most people like around 20 hours. Under-steeping tastes weak; over-steeping turns bitter.
4. Filter twice for clarity: Pour through a fine mesh strainer first, then a paper filter (like OXO Cold Brew Paper Filters) to catch fine sediment. A clean concentrate stores better and tastes smoother.
5. Store in the fridge and dilute: Transfer to an airtight glass jar and refrigerate. Use within 7–14 days. To serve, dilute with equal parts water or milk, or adjust to taste. Dilution ratio is personal—start with 1:1 and adjust.

Gear That Makes Cold Brew Easier

• J Scale 4000: Different types of coffee have different sizes and densities, so weighing your coffee is a foolproof way of getting your dose right. For a consistent cold brew concentrate, weighing your coffee and water ensures you stick to your chosen ratio every batch—no guesswork.
• OXO Cold Brew Coffee Paper Filters, 50PK: Optional for the Oxo Compact Cold Brew Coffee Maker, this filter provides an extra layer of filtration for a distinctly cleaner cold brew extraction. Using a paper filter after steeping removes fine particles that cause sediment and bitterness, giving you a smoother, longer-lasting concentrate.

Making cold brew concentrate at home is all about controlling the basics: ratio, time, and storage. Start with a 1:4 ratio, steep for around 20 hours at room temperature, filter thoroughly, and keep it cold. With these steps, you'll consistently enjoy a smooth, rich concentrate that makes great iced coffee—and a few cocktails—all week. Experiment with different beans and ratios to make it your own.