How to Make Cold Brew Coffee at Home: Foolproof Ratio, Timing, and Flavor Tweaks

If you love the smooth, low‑effort magic of iced coffee, learning how to make cold brew coffee at home is the upgrade your mornings deserve. Cold brew is forgiving, scales easily, and stays tasty in the fridge all week. It’s also wildly popular—recent National Coffee Association data shows roughly one in five U.S. adults had a cold brew in the past week, with Gen Z and Millennials leading the charge (hello, summer on repeat). That momentum is your cue to master a simple, reliable method you can tweak to your taste. We’ll cover a foolproof ratio, brew time that actually fits real life, safety and storage, and a few flavor nudges so every glass feels like a tiny win.

What cold brew is (and isn’t)

Cold brew is a full‑immersion method: coarsely ground coffee steeps in cool water for hours, then you strain and chill. That’s different from iced coffee, which is hot coffee cooled over ice. Cold brew’s lower brew temperature extracts differently—less sharp acidity and a rounder sweetness for many coffees. Importantly, “less acidic” in taste doesn’t mean a higher pH. A peer‑reviewed study found cold and hot brews have similar pH, while hot brews extract more total acids and antioxidant compounds. Takeaway: choose cold brew for flavor and convenience, not as a medical workaround; if you’re sensitive, test gently and listen to your body. See the study overview and full text for the chemistry details.

What you’ll need (no fancy gear required)

• A lidded jar or pitcher (1–2 liters) and space in the fridge
• A scale or measuring cups (weighing is most consistent)
• Paper filter bags, a pour‑over cone with filter, or a fine‑mesh strainer plus a clean kitchen towel
• Fresh, whole‑bean coffee you’re excited to drink—browse our rotating picks in the Coffee collection
• Optional: a second bottle for ready‑to‑drink batches

The foolproof cold brew ratios (concentrate vs ready‑to‑drink)

There are two sensible ways to brew:

• Concentrate (space‑saving, flexible): 1 part coffee to 5 parts water by weight (1:5). Dilute to taste for serving.
• Ready‑to‑drink (pour straight over ice): 1 part coffee to 12 parts water by weight (1:12).

If you don’t have a scale, use heaping cups as a proxy—just be consistent with the scoop you choose. For most home fridges, a 1‑liter batch is perfect and prevents “forgotten jar” syndrome.

Quick reference (1‑liter batches)

• Concentrate: 200 g coffee + 1,000 g water → strain → store as concentrate; serve at roughly 1:1 with water, milk, or melted ice.
• Ready‑to‑drink: 85 g coffee + 1,000 g water → strain → pour over ice as‑is.

Adjust strength on day two by changing your dilution (easier) before you change your brew recipe.

Step‑by‑step: your first great batch

1. Grind coarse. Aim for breadcrumbs—our grind size chart shows where “coarse” sits across brew methods.
2. Add water. Use clean, chlorine‑free water; if your tap tastes “pool‑y,” run it through a carbon filter first. Our coffee water guide explains why this one tweak can be night‑and‑day for flavor.
3. Stir gently. Make sure every grind is wet; dry pockets under‑extract.
4. Cover and refrigerate. Tuck the jar in the back of your fridge.
5. Steep 12–18 hours. That window delivers a sweet spot for most beans.
6. Strain twice. First through a fine strainer to catch the big stuff, then through a paper filter (or filter bag) for clarity. Chill.
7. Serve. For concentrate, start 1:1 with cold water or milk; for ready‑to‑drink, pour straight over ice. Taste, then nudge stronger or weaker tomorrow.

Brew time, simplified (and what new research says)

You’ll see recipes that insist on 18–24 hours. Good news: you probably don’t need that long. Recent UC Davis Coffee Center work found that roast level shaped flavor most, followed by temperature, while brew time was the least important of the three within typical ranges. In practice, that means an overnight brew (around 12 hours in the fridge) can taste just as satisfying as an all‑day soak—especially if your beans fit your vibe. If you’re curious, split a batch and compare 12 vs 18 hours side‑by‑side; choose the one that tastes better to you and your mornings.

Grind, water, and taste: the three biggest levers

• Grind size: Coarser grinds slow extraction and emphasize smoothness; too coarse can taste hollow. Finer grinds speed extraction; too fine can taste muddy or bitter. Use small moves and our grind size chart to steer.
• Water quality: If you’ve ever had a cup that tastes flat, start here. Neutral‑tasting, chlorine‑free water in the moderate‑minerals zone makes cold brew pop. Our Coffee Water 101 breaks down easy upgrades (like NSF/ANSI 42 carbon filters) in plain English.
• Tasting and tweaking: Lock your ratio for three batches and only change one thing at a time. Nudge grind first, then brew time, then dilution.

Which beans shine in cold brew?

Cold brew spotlights chocolate, caramel, nutty, and ripe‑fruit notes. If you want cozy and crowd‑pleasing, reach for chocolatey Latin American profiles. If you love lively citrus or berry, East African coffees can still sing cold—just don’t over‑dilute them. Darker roasts feel richer on ice; lighter roasts feel brighter and tea‑like. Sensitive to caffeine or brewing for evenings? Make a concentrate with decaf and dilute 1:1 for a silky, sleep‑friendly glass. Explore fresh options in our Coffee collection and keep one “house cold brew” you know by heart.

Safety and storage (read this, then relax)

Because cold brew steeps without heat and hangs out for hours, treat it like a perishable beverage. The simplest home rule: brew and store in the refrigerator, keep it sealed, and finish it within a week for best flavor. For context, food regulators in some states classify retail cold brew as a time/temperature control for safety (TCS) product—meaning it must be kept at 41°F (5°C) or colder and date‑marked for seven days. Even though you’re brewing at home, the spirit of those rules is smart: stay cold, stay clean, and don’t push the timeline. If anything looks or smells off, discard and start a fresh batch. Clean your jar and filters between brews.

A quick table for ratios and timing

Type	Coffee:Water (by weight)	Steep time (fridge)	How to serve
Concentrate	1:5	12–18 hours	Start 1:1 with water or milk; adjust to taste
Ready‑to‑drink	1:12	12–18 hours	Pour over ice; tweak next batch stronger/weaker

Troubleshooting by taste (match the fix to the flavor)

• Too weak or tea‑like: Use a stronger ratio next time (from 1:12 to 1:10 ready‑to‑drink, or dilute concentrate less). Or extend steep by 2–4 hours.
• Bitter or astringent: Grind a touch coarser and/or shorten steep time by a few hours. If you brewed concentrate, add more dilution at serving.
• Muddy or silty: Filter through paper after the metal strainer; fines cloud flavor. Consider a coarser grind and gentler stirring.
• Flat or dull: Check water quality and your dilution. Many coffees taste happiest with a little less water than you think.
• Not sweet enough: Try a different origin or roast. Roast level often drives flavor differences more than time tweaks. A chocolate‑forward Peru or Sumatra can feel naturally sweeter on ice.

Flavor add‑ins (keep it simple)

• Vanilla or cinnamon: Add a tiny pinch to the grounds before brewing, or a drop of vanilla to the glass.
• Citrus twist: Express an orange peel over the glass for aroma without sweetness.
• Sparkling cold brew: Top an ounce or two of concentrate with sparkling water and ice for a bright, soda‑like lift.
• Milk choices: Whole milk, oat, or condensed‑milk splashes each highlight different notes. Start small so coffee still leads.

Scale up (or down) without drama

Once your base recipe tastes great, scale the numbers proportionally. For picnics, two liters of concentrate (400 g coffee + 2,000 g water) serve a crowd when you bring extra ice and sparkling water for on‑the‑spot dilutions. For solo weeks, 500‑ml ready‑to‑drink batches stay fresher and help you learn faster.

Why cold brew still isn’t “less acidic” (the myth, politely popped)

You’ll hear claims that cold brew is “low acid.” It can taste smoother, yes—but the pH (a measure of acidity) is comparable to hot brew in controlled tests. The key differences are which acids and how much total acid make it into the cup, plus how cold temperature mutes sharp sensory edges. If your stomach is sensitive, try smaller servings, change beans, or go decaf before assuming cold brew solves it. For the curious, the Scientific Reports paper on pH, titratable acidity, and antioxidants is a great read.

Your next best step

Pick a coffee you’re excited to drink on repeat, set up a 1‑liter jar tonight, and label the lid with ratio, grind, and time. Tomorrow, pour over ice and decide what you’ll tweak (or keep). When you’re ready for a new flavor lane, explore our fresh picks in the Coffee collection. Better sips, calmer mornings—happiness, brewed.

References and further reading (friendly, not fussy)

• Scientific Reports research on cold vs hot brew pH and antioxidants (plain‑English coverage and open‑access full text).
• UC Davis Coffee Center summary on brew time vs roast level for cold brew flavor.
• Regulatory context on keeping retail cold brew at 41°F with seven‑day date marking.
• Market snapshot: cold brew consumption trends and industry resources from the National Coffee Association.