Cold brew is coffee made by steeping coarsely ground beans in cold or room-temperature water for 12 to 24 hours, then straining out the grounds. Unlike regular coffee, no heat is involved at any point in the brewing process. The result is a smooth, naturally sweet concentrate you can dilute with water or milk and serve over ice.
How Cold Brew Differs From Iced Coffee
The distinction comes down to temperature during brewing, not temperature in the cup. Iced coffee is regular hot-brewed coffee that’s been cooled down and poured over ice. Cold brew never touches hot water. That single difference changes the chemistry of extraction in ways you can taste immediately.
Hot water is aggressive. It pulls a wide range of compounds out of coffee grounds quickly, including bitter oils, certain acids, and aromatic molecules that evaporate fast. Cold water works slowly and selectively. A 2022 study published in the journal Foods used chemical profiling to compare the two methods and found that 16 specific compounds, including plant-derived oils and several types of acidic molecules, were significantly more abundant in hot-brewed coffee. Cold water simply doesn’t have enough energy to extract them efficiently. The practical result: cold brew tastes less bitter and less sharp, with a rounder, almost chocolatey sweetness that hot brewing rarely achieves.
The Acidity Question
Cold brew has a reputation for being easier on the stomach, and the chemistry partially supports that. Researchers at Thomas Jefferson University measured the pH of both hot and cold brew coffee and found them surprisingly similar, ranging from 4.85 to 5.13 across all samples. So in terms of raw pH, the two are nearly identical.
The difference shows up in a measurement called titratable acidity, which captures the total concentration of acidic compounds in the liquid, not just the pH reading. Hot-brewed coffee consistently had higher titratable acid levels than cold brew across every bean variety tested. That means hot coffee contains a greater overall load of acids, even if the pH number looks comparable. For people who experience heartburn or stomach discomfort from coffee, this lower acid concentration in cold brew may explain why it feels gentler. The same study also found that hot brew had higher antioxidant activity, likely because those same acidic compounds carry antioxidant properties.
Caffeine Content
A standard 16-ounce serving of cold brew contains around 200 mg of caffeine. That’s roughly comparable to a same-sized cup of drip coffee, though the number shifts depending on how much you dilute the concentrate. Because cold brew starts as a concentrate, you control the strength. Cut it with more water or milk and the caffeine drops accordingly. Drink it less diluted and you’ll get a noticeably stronger kick than a typical cup of hot coffee.
How to Make It at Home
Cold brew requires no special equipment. A mason jar, a fine-mesh strainer or cheesecloth, ground coffee, and filtered water are all you need.
Start with a medium-coarse grind. Counter Culture Coffee recommends about a seven on a 1-to-10 coarseness scale, just slightly coarser than what you’d use for a pour-over. Going too coarse makes the brew taste thin and sour because the water can’t extract enough of the natural sugars. Going too fine leads to over-extraction and a muddy, bitter result. If your first batch tastes sour, grind a touch finer next time.
Combine the grounds with cold filtered water in a covered container. A common starting ratio is about one part coffee to five parts water by weight for a concentrate, though recipes vary. Let it steep in the refrigerator (or on the counter) for 12 to 24 hours. Shorter steep times produce a lighter, more tea-like drink. Longer steeps yield a richer, more intense concentrate. After steeping, strain out the grounds thoroughly. What you’re left with is concentrate that you’ll typically dilute at a ratio of roughly one part concentrate to one or two parts water or milk, adjusted to your taste.
How Long Cold Brew Lasts
One of cold brew’s practical advantages is its shelf life. Undiluted concentrate keeps in the refrigerator for up to two weeks. Once you’ve added water or milk, the clock speeds up. Diluted cold brew stays fresh for two to four days before oxidation makes it taste flat and stale. The exact window depends on your beans, roast level, and grind size, but three to four days is a reliable guideline for diluted batches.
Store-bought cold brew follows different rules. Unopened, it lasts until the printed expiration date. Once opened, plan to finish it within seven days.
Why Cold Brew Has Gone Mainstream
Cold brew went from a niche cafe offering to a grocery store staple remarkably fast. The global cold brew market was valued at $3.87 billion in 2025 and is projected to reach $24.37 billion by 2034, growing at roughly 23% per year. That growth reflects a shift in how people drink coffee. Ready-to-drink cold brew in cans and bottles fits into routines that a hot cup of drip coffee doesn’t, especially for people grabbing something on the go or looking for a coffee that works well with flavored syrups, oat milk, or protein supplements.
The brewing method also appeals to people who find hot coffee too acidic or too bitter. Because the flavor profile is naturally smoother, cold brew requires less sugar to taste balanced. That combination of convenience, flavor, and perceived health benefits has turned it into one of the fastest-growing segments in the coffee industry.