The short answer: for cold brew concentrate, steep coarse-ground coffee in cold water at 1:5 by weight for 8 to 12 hours, then dilute roughly 1:1 in the glass. For ready-to-drink strength, brew at 1:15 and skip the dilution. And treat the acidity claims on cans with suspicion: measured pH runs close to hot coffee's.
What ratio should I use for cold brew?
Pick by how you plan to drink it. Both of these work in a mason jar, a French press, or any pitcher; no purpose-built brewer required.
| Style | Ratio (coffee:water, by weight) | Example | Serve |
|---|---|---|---|
| Concentrate | 1:5 | 100 g coffee, 500 g water | Dilute about 1:1 with water or milk, over ice |
| Ready to drink | 1:15 | 60 g coffee, 900 g water | Straight over ice |
Weigh the coffee rather than scooping it; a $15 kitchen scale removes the biggest source of batch-to-batch mystery, the same argument we made for hot brewing ratios. Grind coarse, like rough sea salt. Stir once to wet everything, cover, steep, then strain through a paper filter, a fine sieve, or the press screen. If numbers between 1:5 and 1:15 tempt you, follow the temptation. The ratio dial is continuous, and dogma has no seat at this table.
How long should cold brew steep, and does the fridge change it?
Overnight is enough. Jiexin Liang and colleagues at UC Davis ran full-immersion brews at cold, room, and hot temperatures across a time series (Scientific Reports, 2024), with a trained panel scoring 28 flavor attributes. Two findings matter for your kitchen. Extraction plateaus: after roughly 8 hours, longer steeps changed the cup less than expected, and 8-hour brews tasted close to 24-hour ones. And the roast on the bag shaped flavor more than brew time or temperature did, so bean choice is the loudest dial you have. "Stronger because I forgot it for two days" is mostly a myth; past the plateau you add slow, woody notes, not strength.
Room temperature steeps run a little faster than fridge steeps, so aim for the lower end of the window on the counter and the upper end in the fridge. We steep in the fridge for the simple reason that the result is already cold and keeps better. Strained cold brew holds up about a week refrigerated; after that it fades rather than spoils dramatically.
Is cold brew really less acidic?
This claim sells a lot of cans, so it earned a place in Second Look, our coffee science series in the Journal. Niny Rao and Megan Fuller, chemists at Thomas Jefferson University, measured hot and cold brews of the same coffees (Scientific Reports, 2018). The pH values landed in the same narrow band, roughly 4.85 to 5.13, for both methods. Hot brewing did extract a higher total load of acids (chemists call the measure titratable acidity), so cold brew is somewhat lower in total acid content. But the dramatic version of the claim, cold brew as a different, stomach-friendly beverage class, is not what the chemistry shows. The same team found hot brews carried more antioxidants too, which complicates the wellness framing further.
Why does cold brew taste smoother, then? Serving temperature, dilution, milk, and roast choice do a lot of that work, and lower total acids do some. Enjoy the smoothness; skip the health mythology. If regular coffee upsets your stomach, that is worth a conversation with a doctor rather than a different pitcher.
How do I scale a batch without the math going sideways?
Hold the ratio and multiply. A 2-liter pitcher of ready-to-drink is 130 g of coffee to 1,950 g of water (1:15). A week of concentrate for two espresso-tolerant adults is 200 g of coffee to 1,000 g of water (1:5), which dilutes out to roughly 2 liters of finished drinks. Note the one place scaling bites: the grounds drink some of the water, holding onto roughly twice their weight, so a 1:5 batch returns about 60 to 70 percent of the water you poured in as finished concentrate. Budget for that loss rather than being surprised by it, and squeeze nothing; pressing the spent grounds pushes silt and bitterness into a clean batch.
Two serving ideas that earn their place: concentrate 1:1 over ice with a pinch of salt in the glass rounds off bitter edges, and concentrate poured 1:1 with cold milk is the fastest iced latte in the house, no machine involved. Top either with cold foam and you have replaced a $7 line item.
Why does my cold brew taste weak, bitter, or woody?
Diagnose by taste, the same way we approach every brewing problem on this site. Weak usually means the ratio drifted (recount grams, not scoops) or the grind was too coarse for the steep time; tighten one of them, not both, so you know which change did the work. Silty and bitter means the grind was too fine, so the long steep over-extracted the fine particles; go coarser and strain through paper. Woody and flat usually means the steep ran a day past the plateau or the beans were stale; cold brew is forgiving, but it cannot rewind a badly stored bag. Fresh beans at any roast level you enjoy work; the UC Davis panel found roast level dominates the flavor, so choose the roast you like drinking rather than a designated "cold brew blend."
FAQ
What is the ratio for cold brew concentrate?
1:5 coffee to water by weight, steeped 8 to 12 hours and diluted about 1:1 when served. For a stronger concentrate some brewers go to 1:4; dilute a little more and the math evens out.
Should cold brew steep at room temperature or in the fridge?
Both work. Room temperature extracts a bit faster (use the shorter end of 8 to 12 hours); the fridge is slower, safer to forget, and delivers a cold, ready pitcher. Flavor differences are small next to ratio and roast choice.
Can I use any beans for cold brew?
Yes. The UC Davis sensory study found roast level shapes cold brew flavor more than steep time does. Medium and darker roasts give the classic chocolatey profile; lighter roasts stay brighter and more tea-like. Brew what you like to drink.
Is cold brew stronger than iced coffee?
Depends on dilution, not on the method. Undiluted concentrate is far stronger than iced filter coffee; diluted to taste, they land in the same range. Caffeine follows the same logic: the ratio in your glass decides it, so a gently diluted concentrate can out-caffeinate a hot cup or land well under it, entirely by your pour.
The shoulders this stands on
Niny Z. Rao and Megan Fuller, Thomas Jefferson University, "Acidity and Antioxidant Activity of Cold Brew Coffee," Scientific Reports, 2018. Jiexin Liang, Mackenzie Batali, Catherine Routt, William Ristenpart and Jean-Xavier Guinard, UC Davis, "Sensory analysis of the flavor profile of full immersion hot, room temperature, and cold brewed coffee over time," Scientific Reports, 2024. Ratios and fridge habits are our own bar's practice. If cold drinks with foam are your weakness, the cold foam guide is this article's natural dessert.
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