How to Make Cold Brew Concentrate
Cold brew coffee concentrate is just coffee left to steep in cold water for hours, then strained into something strong enough that you dilute it later. It’s not the same as regular cold brew, which you can drink straight from the jug. Concentrate is the practical version: make a batch once and you’ve got iced coffee, lattes or the base for an espresso martini sorted for days or weeks. Nail the ratio and the grind and it’s almost hard to mess up. Get either wrong and you end up with watery stuff or something so bitter you wonder why you bothered.
Here’s the way I do it now, with the ratio in grams and cups, the mistakes that catch most people, and an honest take on whether it’s worth the faff versus just buying a bottle.
What is cold brew concentrate
Cold brew coffee concentrate is ground coffee steeped in cold or room-temperature water for 12 to 24 hours, then filtered. No hot water, no drip coffee maker. Because there’s no heat, extraction happens slowly and you get fewer of the sharp acids and bitter notes that hot water pulls out fast. The result is smoother and less acidic than hot brewed coffee, but a lot stronger — that’s why it’s concentrate, not a finished drink.If you want the full comparison with iced coffee (just hot coffee cooled down and poured over ice), there’s a separate cold brew vs iced coffee guide for that.
The best cold brew concentrate ratio
Most people who take this seriously land between 1:4 and 1:5 coffee to water by weight. That works whether you’re using a jar, a cafetiere or a French press. Some UK setups go as high as 1:8 for volume, but at home 1:4 is the one worth remembering.
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Batch size
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Coffee (grams)
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Water (filtered)
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Small jar
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100g
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400ml
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Standard batch
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150g
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600ml
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Large batch
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225g
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900ml
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No scales? Roughly 1 cup of coarsely ground coffee to 4 cups of cold water. It’s not perfect because a cup of coffee grounds varies with grind size, but it’s close enough while you figure out what you like. I switched to weighing everything a couple of years ago and the batches got noticeably more consistent. A cheap kitchen scale is worth it if you do this regularly.
How to make cold brew concentrate: step by step
Grind and beans
Coarse grind — think coarse sea salt. Too fine and you over-extract into bitterness and end up with sludge that’s a nightmare to filter. A burr grinder is better than a blade one here because the coffee sits in the water for so long; evenness matters more than usual. Pre ground coffee will do in a pinch, but freshly ground is cleaner. Coffee starts losing aroma minutes after grinding. Medium to dark roast tends to work best. The long steep brings out the chocolate and caramel notes those beans already have. If you don’t want to grind, there are cold brew coffee beans roasted specifically for this.
Steep
Mix your coarsely ground coffee beans with cold, filtered water in a big jar or pitcher. Stir properly so you don’t leave dry pockets of coffee grounds sitting on top. Cover and stick it in the fridge for 12 to 24 hours. Sixteen is a solid middle ground if you’re not sure. Room temperature can pull a bit more flavour, but the fridge is safer for longer steeps.
Filter, twice if you can
First through a fine mesh sieve to get the bulk of the grounds. Then again through a paper coffee filter or muslin. That second pass is the difference between clean concentrate and something cloudy and a bit oily. I used to skip it to save time and regretted it every time. Five extra minutes is worth it.
Pour the finished concentrate into an airtight container and keep it in the fridge.
How to make decaf cold brew concentrate
Same method. Decaf beans are processed differently and can be oilier, so they clog a paper filter faster. Go a bit coarser on the grind and take your time filtering. There’s a full guide on how to make decaf cold brew coffee if you want more detail, and ready bags exist if you don’t have a coffee grinder.
Common mistakes that make weak or bitter concentrate
Most people complain their homemade cold brew concentrate comes out too weak. Usually it’s one of these.
Grind too fine. It extracts faster but also clogs the filter, so people add more water and dilute everything. Stick to coarse grind.
Batch too small. A little coffee in a lot of water never concentrates properly. If your first go tastes thin, add more coffee rather than just steeping longer.
Steeping under 12 hours doesn’t give enough contact time for real body. Past 24 hours and it tips into harsh and astringent instead of stronger.
And the obvious one: don’t drink it neat. Cold brew concentrate is meant to be diluted. If it still tastes weak after you followed the ratio, you might just be drinking it at the wrong strength.
How much caffeine is in cold brew concentrate
It’s concentrated, so a typical serving before dilution can sit around 150–200 mg of caffeine. That’s more than a single espresso (about 63 mg) or a standard cup of filter coffee (around 95 mg). Exact numbers shift with ratio, steep time and the beans, so take it as a rough guide. Sensitive to caffeine? Dilute more, or mix regular and decaf beans for a half-caff batch.
How to dilute and serve cold brew concentrate
Equal parts concentrate and cold water over ice is the standard cold brew. Smooth, not watery. Swap the water for milk or a plant alternative and you’ve got an iced latte with almost no work. It works hot too — dilute with hot water if you want a mellow coffee without brewing fresh. One trick I like: freeze leftover concentrate into coffee ice cubes. As they melt they strengthen the drink instead of watering it down.
For coffee cocktails, cold brew concentrate holds up better than espresso when you shake it with ice. A simple starting point for one espresso martini: 30 ml cold brew concentrate, 25 ml vodka, 25 ml coffee liqueur, a splash of simple syrup if you want it, shaken hard and strained into a chilled glass.
Homemade vs shop-bought cold brew coffee concentrate
You’ve probably seen the ready-made bottles on supermarket shelves. Here’s the honest comparison.
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Homemade
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Tesco / supermarket own brand
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Nescafe cold brew
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Quarterpast
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Solo Coffee
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Cost per litre
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Roughly £1 to £2 depending on beans
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Around £4 to £6
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Around £5 to £7
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Around £4 to £6
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Higher, aimed at bars
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Strength
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Fully adjustable
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Fixed, usually mild
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Fixed
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Fixed
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Espresso strength, made for cocktails
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Flavour control
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Full control over beans and roast
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Limited
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Limited
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Limited, often flavoured
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Designed specifically for espresso martinis
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Convenience
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Needs 12 to 24 hours planning
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Instant
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Instant
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Instant
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Instant
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If you just want something now, grab a bottle from Tesco or a can of Nescafe. If you already buy decent beans and drink coffee regularly, making your own is cheaper and you can make it exactly as strong as you like. None of the shop versions let you do that.
How long does cold brew concentrate last
In a sealed airtight container in the fridge it keeps for one to two weeks. Once you’ve diluted it, drink it that day. There’s a longer guide on how long cold brew lasts if you want the full details on spotting when it’s gone off.
Frequently Asked Questions
What is the ratio for cold brew concentrate?
Most recipes use 1 part coarsely ground coffee to 4 parts cold, filtered water by weight. Some go up to 1:8. Steep 12 to 24 hours, filter twice. Adjust after you’ve made a couple of batches.
Is cold brew concentrate better with milk or water?
Depends what you want. Water keeps it cleaner and closer to classic cold brew. Milk (or plant milk) makes it more like a latte. Start equal parts and tweak from there.
How long does cold brew concentrate keep?
One to two weeks in an airtight container in the fridge. Diluted versions don’t last as long once you’ve added water or milk, so make them up fresh.
Is there a difference between cold brew and cold brew concentrate?
Yes. Regular cold brew is ready to drink. Concentrate is stronger on purpose and needs diluting. That makes it more flexible — you can adjust the strength or use it neat in cocktails and baking.
