Master the ratio cold brew coffee for flawless flavour

Get the balance of coffee to water right, and you've unlocked the secret to incredible cold brew. It’s easily the most important part of the whole process.

For a punchy cold brew concentrate, you'll want to aim for a ratio between 1:4 and 1:8 (that's one part coffee to four-to-eight parts water). If you prefer something you can sip straight away, a lighter 1:12 to 1:16 ratio will give you a smoother, less intense flavour.

Your Journey to Flawless Cold Brew Starts Here

Welcome to our definitive guide for UK home brewers ready to master the art of cold brew. Let's leave weak, watery results and overly bitter concoctions in the past. We're here to demystify the entire process, starting with the absolute foundation: the perfect coffee-to-water ratio.

This guide gives you the exact measurements and simple techniques you need to create consistently delicious cold brew, whether you like a potent concentrate for mixing or a smooth, ready-to-drink brew. By getting a handle on your ratios, you take complete control over the final taste in your cup.

Why Has Cold Brew Taken Over the UK?

The magic of cold brew isn't just that it's a refreshing drink. The slow, gentle extraction, using cold water over many hours, creates a coffee that’s fundamentally different from its hot-brewed cousins. This patient method gives you a brew that is:

• Naturally Sweeter: Because cold water doesn't pull out as many bitter compounds, the coffee's own inherent sweetness really gets a chance to shine.
• Noticeably Less Acidic: The process results in a coffee with up to 67% less acidity than traditional hot coffee, making it much kinder on your stomach.
• Incredibly Smooth: That long, slow steep builds a full-bodied but exceptionally smooth texture, without the harshness you sometimes get from hot extractions.

This unique flavour profile has really struck a chord with coffee lovers across the UK. The ready-to-drink (RTD) coffee market, which cold brew is a huge part of, is booming. It's projected to grow from a value of £490.97 million in 2025 to £520.84 million in 2026. Within that, cold brew itself is expected to grow at a compound annual rate of 7.29% between 2026 and 2031, with younger drinkers in England and Scotland leading the charge. You can dig into more of this data on the UK's RTD coffee market over at Mordor Intelligence.

Cold brew isn't just chilled coffee; it's a completely different brewing philosophy. It trades the speed and intensity of heat for the patience and subtlety of time, unlocking a smoother, sweeter side of the coffee bean.

Starting with high-quality, freshly roasted beans is how you'll elevate your homemade brew from just "good" to genuinely exceptional. The coffee you choose is just as crucial as the ratio. For some solid recommendations, have a look at our guide on selecting the best coffee for cold brew.

Now, let's get into the details of ratios, grind sizes, and steeping times so you can start brewing with total confidence.

Cracking the Code: Finding Your Perfect Cold Brew Ratio

The single most important decision you'll make when brewing cold brew is the ratio of coffee to water. It’s the dial that controls everything from strength and texture to the final flavour. Getting this right is the difference between a sad, watery brew and a rich, satisfying cup that sings.

So, where do you start? Your first choice boils down to a simple question: are you making a versatile concentrate or a batch that's ready to drink straight away? There's no right or wrong answer here; it all depends on your routine and how you like your coffee.

The Concentrate Approach: Strong and Versatile

Making a cold brew concentrate means using a much tighter ratio of coffee to water, usually somewhere between 1:4 and 1:8. For every one part of coffee, you’re using four to eight parts of water, always measured by weight for accuracy.

This method gives you a potent, full-bodied liquid that’s way too strong to drink on its own. The real magic is in its flexibility. A good concentrate is a brilliant base you can dilute to your exact taste.

A great starting point is a 1:5 ratio. So, if you use 100g of coarsely ground coffee, you’ll add 500g (which is the same as 500ml) of water. After it’s steeped, you'll have a powerful brew ready for anything:

• Classic Iced Coffee: Mix your concentrate with an equal part of cold water or milk over ice. Perfectly balanced, every time.
• Quick Hot Coffee: No time to wait for the kettle? A splash of hot water into your concentrate gives you a smooth, instant hot coffee.
• Creative Cocktails: The bold flavour of a 1:4 or 1:5 concentrate holds up beautifully in coffee cocktails like an espresso martini.
• In the Kitchen: It’s also fantastic for adding a deep coffee flavour to desserts, from tiramisu to homemade ice cream.

The strong ratio pulls out a dense concentration of flavours, often highlighting the rich, chocolatey, and nutty notes in the coffee. It’s the perfect choice if you value efficiency and love having a ready-to-go coffee base in the fridge.

The Ready-to-Drink Method: Smooth and Simple

If you'd rather skip the extra step of dilution, brewing a ready-to-drink (or RTD) cold brew is for you. This approach uses a lighter, more forgiving ratio, typically from 1:12 to 1:16.

Using a lighter ratio means your final brew is perfectly drinkable straight from the jar. Just filter, pour over ice, and you're good to go. This method is ideal for teasing out the more delicate and nuanced flavours in your beans.

Your choice of ratio is a personal one. A 1:5 concentrate offers versatility for the week, while a 1:14 ready-to-drink batch provides instant gratification with a focus on subtle flavours.

Before we dive into a comparison, it's worth noting how much we Brits have embraced this brewing style. Cold brew is a massive part of the global coffee scene, and the UK is a key area of growth. The worldwide market, valued at USD 1.25 billion in 2025, is projected to hit nearly USD 2.4 billion by 2032. Here at home, the market is expected to reach USD 0.23 billion by 2026, which shows just how popular it’s become.

Ratio Comparison: Concentrate vs Ready-to-Drink

Deciding between a concentrate and a ready-to-drink brew comes down to how you plan to use it. This table breaks down the main differences to help you choose the right path for your lifestyle.

Ultimately, both methods produce a fantastic cold brew. Your choice simply reflects whether you prioritise flexibility or immediate enjoyment.

How Your Coffee Choice Shapes the Ratio

The perfect ratio isn't just about strength; it’s about making your chosen beans shine.

A bright, fruity single-origin from Ethiopia, for instance, might taste phenomenal as a 1:14 ready-to-drink brew. The lighter ratio lets its delicate floral and citrus notes come through without being overpowered. On the other hand, a rich, full-bodied blend with notes of chocolate and caramel, like many from Brazil, makes an excellent 1:5 concentrate. The stronger extraction deepens those comforting flavours.

Don't be afraid to experiment. The ratios we've talked about are fantastic starting points, but your own taste is the ultimate guide. Start with a 1:5 for concentrate or a 1:14 for ready-to-drink, taste the result, and tweak your next batch. You're in charge of your brew, and finding that perfect balance is a rewarding journey.

Of course, the ratio is only half the battle; the coarseness of your grind is just as important. To make sure you’ve got that spot on, check out our detailed coffee grind size guide.

Getting Your Hands Dirty: The Cold Brew Method

Alright, now that we've talked ratios, it's time for the fun part. This is where your beautiful coffee beans and good-quality water finally meet. We'll go through the whole process together, from getting the grind right to that final, satisfying filter, so you can nail it every single time.

Don't be intimidated. The process is wonderfully straightforward and forgiving, which is why it's brilliant for home brewing. You don't need a load of fancy gear either—a simple Mason jar or your trusty French press will do the job perfectly.

Why a Coarse Grind is Non-Negotiable

First thing's first: the grind. This is one of the most critical steps, and for cold brew, you absolutely need a coarse grind. Think of the texture of rough breadcrumbs or chunky sea salt. Getting this right is the key to managing extraction.

If your grind is too fine, you'll over-extract the coffee, even with cold water. The result? A brew that's bitter, muddy, and leaves a chalky feeling in your mouth. The larger particles of a coarse grind allow the water to gently work its magic over the long steep, pulling out all those sweet, smooth flavours without grabbing the harsh, bitter compounds we want to leave behind. Grinding your beans fresh just before you brew is always going to give you the most vibrant results.

Mixing Your Coffee and Water

With your coffee perfectly ground, it's time to introduce it to some cold, filtered water. While a dedicated brewer like the Mizudashi Cold Brew Coffee Maker can make things a little tidier, honestly, any large jar or pitcher works just as well.

Start by tipping your weighed coffee grounds into your container. Next, pour in the correct amount of water based on the ratio you've chosen (say, 1:5 for a punchy concentrate or 1:14 if you want it ready to drink).

Here's a little tip: pour about half the water in first and give it a gentle stir. Your goal is to make sure all the coffee grounds are fully saturated. Once you're sure there are no dry clumps, go ahead and add the rest of the water. This little "bloom" and stir prevents pockets of dry coffee, which means you get a much more even and delicious extraction.

The Waiting Game: How to Steep Your Brew

Now for the easiest part, which also happens to be the most important: you wait. Just cover your container and let the coffee steep. How long you leave it really depends on where you put it.

• At Room Temperature: Leaving it on the kitchen counter usually takes about 12 to 18 hours. The slightly warmer air speeds up extraction a bit, often resulting in a brew with deep, chocolatey notes.
• In the Fridge: A cold steep in the fridge slows everything right down, so you'll need to be more patient—think 18 to 24 hours. The pay-off is often a cleaner, brighter-tasting coffee that's exceptionally smooth.

There's no right or wrong answer here; it's all down to personal taste. I'd suggest trying both methods to see which flavour profile you prefer.

This diagram gives you a quick visual rundown of the process for both concentrate and ready-to-drink styles.

As you can see, the core steps are identical. It's that initial ratio of coffee to water that determines what kind of brew you end up with.

Filtering for a Silt-Free Finish

Once the long steep is over, it’s time to separate the grounds from your liquid gold. This filtering stage is crucial for getting that clean, sediment-free texture we all love. A gritty cold brew can really spoil the experience, so it’s worth taking your time here.

If you used a French press, it couldn't be simpler. Just slowly and gently push the plunger all the way down to trap the grounds. Then, pour the coffee into a separate bottle or jar for storing.

For those who brewed in a jar, the approach is a little different. Get a fine-mesh sieve and place it over a large bowl or another clean container. Carefully pour the cold brew mixture through the sieve to catch all the big particles.

Pro Tip for an Ultra-Smooth Finish
To get a brew that's unbelievably clean and silky, try double-filtering. After the first strain through the sieve, line it with a paper coffee filter or a couple of layers of cheesecloth. Then, pour the brew through it one more time. This extra step is brilliant for catching all those super-fine particles, or 'fines', that a normal sieve can't.

This simple two-step filtering process is your ticket to a professional-quality texture. For a more detailed look at the entire brewing journey, feel free to check out our full guide on how to make cold brew coffee. Now that you have a perfectly filtered batch, you’re ready to dilute, serve, and store it.

Getting Your Dilution Right and Scaling Up

After all that patient steeping and careful filtering, you’re left with a jar of rich, aromatic cold brew concentrate. This is where the fun really begins. The next step is all about dilution, which turns that potent base into your perfect drink.

Think of your concentrate as the heart of your coffee; dilution gives it its final personality. It's a simple process, but tiny tweaks can make a huge difference to the flavour in your glass.

The Simple Maths of Dilution

The easiest place to start is with a 1:1 ratio. This just means you mix one part concentrate with one part of whatever you're diluting it with. For example, if you pour 100ml of concentrate into your glass, you'll top it up with 100ml of cold water or milk before adding ice. Simple.

This 1:1 mix creates a smooth, flavourful drink that’s roughly as strong as a standard hot coffee. It’s the perfect baseline to get you started, letting you taste the result and decide if you want to go stronger or weaker next time.

Your taste buds are the best guide here. Start with 1:1, have a sip, and adjust. Prefer it with a bit more punch? Try a 1:0.75 ratio (100ml concentrate to 75ml diluent). Want it a little lighter? A 1:1.5 ratio will do the trick.

Choosing Your Perfect Mixer

While cold water is the classic choice, playing around with different mixers can completely transform your cold brew. Each liquid interacts with the coffee's flavour profile in its own way.

Here are a few popular options to get you started:

• Dairy Milk: Whole milk adds a lovely creamy texture that really complements the deep, chocolatey notes you often find in cold brew.
• Oat Milk: A fantastic dairy-free option. Oat milk brings its own natural sweetness and a velvety body that works beautifully with coffee.
• Tonic or Sparkling Water: For something completely different and refreshing, try adding sparkling water or tonic. You end up with a zesty "coffee spritzer" that's just perfect for a summer afternoon.

Don't forget that the type of water you use for dilution matters, too. For a deeper dive, check out our guide on the best water for coffee in the UK to make sure you’re not accidentally masking your coffee’s delicate flavours.

Scaling Up Your Cold Brew Recipe

Once you've nailed a ratio cold brew coffee recipe you love, making bigger batches is the next logical step. It saves a ton of time and ensures you’ve always got a supply ready to go in the fridge. The key is simply to maintain the exact same ratio you've perfected.

Let’s say your go-to concentrate recipe is 100g of coffee to 500ml of water (a 1:5 ratio). If you want to make a batch five times larger to last the week, the calculation is dead simple.

Scaling Your 1:5 Ratio

By keeping the ratio consistent, you guarantee the flavour and strength of your larger batch will be identical to your tried-and-tested smaller one.

One last tip when you're scaling up: make sure all the coffee grounds get evenly soaked. In a bigger container, it’s easy for dry clumps to hide at the bottom. To avoid this, pour in about half your water, give it a good stir to wet all the grounds, and then add the rest. This little step ensures a consistent, delicious extraction, no matter how big you brew.

Tasting, Tweaking, and Storing Your Cold Brew

Getting your cold brew just right is a rewarding journey of small, satisfying adjustments. That first sip of a new batch is always filled with anticipation, but what do you do if it doesn't taste quite right? Don't worry. Fine-tuning your brew is surprisingly simple, and most issues can be sorted with a quick tweak to your process.

This is your go-to guide for diagnosing common flavour problems and making sure your brilliant creation stays fresh. Think of it as the final quality check that turns a good brew into an exceptional one.

Fine-Tuning The Flavour

Once you’ve locked in a baseline ratio cold brew coffee that you're happy with, the real fun can begin. Even with the exact same beans, tiny changes to your grind size or how long you let it steep can unlock completely new flavour profiles.

Here are a couple of the most common issues and how to fix them:

• Does your brew taste weak or watery? This is a classic sign of under-extraction. It just means the water hasn't had enough contact with the coffee to pull out all the good stuff. The fix is simple: either increase your steep time (try adding another 2-4 hours) or use a slightly finer grind on your next batch.

• Is it tasting too bitter or harsh? Ah, the tell-tale sign of over-extraction. You've pulled too many of the less desirable compounds from the grounds. The solution is the opposite of the above—either shorten the steep time or, often more effectively, switch to a coarser grind.

It's Not Just About Technique

Remember, the coffee itself plays a starring role. The origin of your beans has a massive impact on the final flavour, which is all part of the joy of brewing at home.

For instance, a bag of our single-origin Ethiopian Yirgacheffe will naturally give you bright, floral, and almost citrusy notes in a cold brew. On the other hand, a classic Brazilian Santos will deliver a much richer, nuttier, chocolate-forward profile. Neither is better—they're just different expressions of coffee, and your ratio and steep time can help bring these unique characteristics to the forefront.

Perfecting your cold brew isn't about finding a single "correct" recipe. It's about understanding how to adjust the variables—grind, time, and ratio—to bring out the absolute best in the specific beans you're using.

Keeping Your Cold Brew Fresh

You've put in the time and effort to craft a beautiful batch of cold brew; let's make sure it stays that way. Proper storage is absolutely non-negotiable for preserving those delicate flavours you worked so hard to extract. Oxidation is the enemy here, causing flavours to degrade and turn stale.

Your best friend is an airtight container. A simple glass jar with a tight-fitting lid or a sealed bottle works perfectly. This does two things: it keeps oxygen out and stops your coffee from absorbing any stray odours from the fridge.

To ensure your cold brew stays in top condition, it's crucial to get the temperature right. Diving into the details of mini fridge temperature settings can be a big help, but a good rule of thumb is to aim for somewhere between 1-5°C.

Shelf Life: Concentrate vs Ready-to-Drink

How long your brew will last depends entirely on whether you've made a concentrate or a ready-to-drink version. The difference is significant.

For more tips on keeping things fresh, our guide on how to store coffee beans offers some brilliant principles that apply just as well to brewed coffee as they do to beans.

A Sustainable Sip for UK Brewers

Being a home brewer in the UK often comes with an eco-conscious mindset. Instead of just chucking your spent coffee grounds in the bin, why not give them a second life? They're a fantastic, versatile resource.

Here are a few simple ideas:

• Enrich your garden: Coffee grounds are rich in nitrogen, making them a brilliant addition to your compost or a great top dressing for acid-loving plants like roses and hydrangeas.
• A natural deodoriser: Pop a small bowl of dried grounds in the back of your fridge to help absorb any strong odours.
• Gentle abrasive cleaner: The gritty texture is perfect for scrubbing stubborn residue off pots and pans without resorting to harsh chemicals.

By troubleshooting the taste and storing your brew correctly, you take full ownership of the process. You'll ensure every glass is as delicious as the first, and you can feel good knowing that nothing is going to waste.

Common Questions About Cold Brew Ratios

Once you've brewed a few successful batches, you'll inevitably start wondering how to tweak things for that perfect, signature cup. That’s a great sign—it means you're moving from just following a recipe to truly understanding the craft.

Let’s tackle some of the most common questions we get asked. These are the little details that can make a huge difference, helping you brew with total confidence.

Can I Use Pre-Ground Coffee for Cold Brew?

While you technically can, we really advise against it if you're after the best flavour. Most pre-ground coffee is far too fine for a long, slow steep like cold brew. Using a fine grind often leads to over-extraction, resulting in a bitter, muddy brew with a sludgy, unpleasant texture at the bottom of your cup.

The ideal grind for cold brew is coarse—think rough breadcrumbs. Grinding your beans fresh just before you start is the single biggest step you can take to protect their delicate aromas, giving you a much more vibrant and flavourful result. If you’re in a pinch and must use pre-ground, hunt for a bag that is specifically labelled 'coarse' or 'French press' grind.

Does Steeping on the Counter or in the Fridge Make a Difference?

Yes, absolutely. The steeping temperature has a massive impact on the final taste. Neither way is right or wrong; they just give you different results.

• Room Temperature (Counter): Leaving your brew on the counter speeds up extraction, so you'll only need about 12-18 hours. This method tends to pull out deeper, richer, and more complex notes from the beans, often highlighting those lovely chocolatey and nutty flavours.
• Refrigerated (Fridge): Chilling your brew in the fridge slows the extraction process right down. You'll need to be a bit more patient, as this takes 18-24 hours. The reward is an exceptionally clean, bright, and smooth flavour profile.

We always recommend trying both methods with your favourite beans to see which you prefer. You might find you love a rich, counter-steeped concentrate but prefer a light, fridge-steeped brew to drink straight.

The choice between steeping on the counter or in the fridge is a simple way to steer the flavour of your final brew. Think of room temperature for depth and richness, and the fridge for smoothness and clarity.

How Can I Avoid Sediment in My Final Brew?

A gritty texture is a surefire way to ruin a great cold brew. Thankfully, getting that silky-smooth finish is pretty simple with a two-step filtering process. The trick is to catch both the big grounds and those pesky ultra-fine particles.

We call it 'double filtration', and it works every time. First, do a coarse filter to get the bulk of the grounds out—plunging a French press or pouring the brew through a normal kitchen sieve works perfectly. Then, for the second, crucial pass, line a fine-mesh sieve with a paper coffee filter or a clean bit of cheesecloth. Slowly pour the cold brew through this setup. This final step is what catches all those tiny fines, leaving you with a crystal-clear brew.

How Does Roast Level Affect My Cold Brew Ratio?

The roast level has a subtle but important effect on how your coffee extracts. Darker roasts are more porous and soluble, so they give up their flavour more readily. For a dark roast, you might find a slightly wider ratio cold brew coffee works better (say, 1:6 for a concentrate instead of 1:5) to stop it from becoming too intense or overpowering.

On the other hand, lighter roasts are much denser and extract more slowly. To pull out all their delicate, nuanced notes, you might need a slightly tighter ratio (like 1:12 for ready-to-drink instead of 1:14) or just let it steep for a bit longer. The key is to start with a baseline ratio and be ready to tweak it based on how your first batch tastes.

Ready to put this knowledge into practice with beans that are perfect for the cold brew method? The team at Seven Sisters Coffee Co roasts exceptional single-origin coffees and expertly crafted blends that will truly elevate your home brewing. Explore our freshly roasted selection and find your next favourite coffee.