How to Make Cold Brew Coffee

by Will Penfold | May 25, 2024

TL;DR

Cold brew coffee is made by steeping coarse-ground coffee in cold filtered water for 12 to 24 hours. Furthermore, the slow, cool extraction produces a smooth, low-acid, naturally sweet cup that tastes very different from hot-brewed coffee. As a result, cold brew is the most forgiving brewing method, requiring no special equipment and producing consistently excellent results. Use a 1:10 ratio (100g coffee to 1 litre of cold water), steep in the fridge, then strain. The cold brew lasts up to a week.

What Is Cold Brew Coffee?

Cold brew coffee is a brewing method that uses cold or room-temperature water and a long steep time, typically 12 to 24 hours. Because no heat is involved, the extraction is slower and gentler than hot brewing. As a result, cold brew tastes smoother, less acidic, and naturally sweeter than coffee made by other methods.

This article walks through the full method, the ideal ratio, which beans to choose, and how to serve cold brew. Furthermore, for the broader picture of how brewing shapes flavour, read our pillar guide on how to brew better coffee at home.

Cold Brew vs Iced Coffee

People often confuse cold brew with iced coffee, but the two are very different. Furthermore, the difference is in how the coffee is brewed, not just how it is served:

Cold brew. Brewed with cold water over 12 to 24 hours. Produces a smooth, low-acid, naturally sweet cup. Moreover, the long contact time extracts a different set of flavour compounds.
Iced coffee. Brewed hot with normal hot brewing methods, then poured over ice or chilled. As a result, it preserves the original acidity and brightness but tastes like a chilled version of regular coffee.

Both have their place. However, cold brew is the better choice when you want something smooth, sweet, and less acidic, especially during warmer weather.

Why Cold Brew Tastes So Smooth

Cold brew tastes smoother because of the chemistry of cold extraction. Because hot water extracts acids and bitter compounds quickly, hot-brewed coffee can taste sharp or harsh if anything goes wrong. On the other hand, cold water extracts these compounds much more slowly. As a result, the bitter and acidic compounds barely make it into the final cup.

What you do get is the deeper, sweeter, fuller-bodied compounds that take longer to extract. Consequently, cold brew has a reputation for tasting:

noticeably less acidic
naturally sweet, often with chocolate, caramel, and dried fruit notes
smoother and rounder than hot coffee
full-bodied, almost syrupy

For more on how acidity and sweetness interact in coffee, read our guides on coffee acidity and what makes coffee sweet.

What You Need to Make Cold Brew

One of the joys of cold brew is how little equipment it requires. Furthermore, you almost certainly have everything you need at home already:

Coarse-ground specialty coffee. 100g per litre of water.
Cold filtered water. 1 litre.
A large jar or French press. Anything that holds at least 1.5 litres works.
A fine mesh strainer or paper filter. For straining once steeping is done.
A clean storage jar. For keeping your cold brew in the fridge afterwards.

In addition, fresh, high-quality coffee makes the biggest difference. As a result, the smoother extraction of cold brew highlights bean quality more than it hides it. Choose specialty coffee, ideally roasted within the last 4 to 6 weeks.

The Cold Brew Method in Four Steps

Making cold brew is genuinely simple. Furthermore, once you have the ratio right, the rest is just patience.

Grind the coffee coarsely. Aim for a texture similar to coarse sea salt. Moreover, a fine grind will over-extract and make the cold brew bitter, while too coarse a grind will produce a thin cup. If you don’t have a grinder, ask your roaster to grind for cold brew or French press.
Combine coffee and water. In a large jar or French press, combine 100g of ground coffee with 1 litre of cold filtered water. As a result, you should aim for a 1:10 ratio of coffee to water. Stir gently to make sure all the grounds are fully wet.
Steep in the fridge. Cover the jar or French press and let it steep in the fridge for 12 to 24 hours. Furthermore, longer steeping produces stronger, deeper flavour. 18 hours is a good starting point.
Strain and serve. Strain the coffee through a fine mesh strainer or paper filter into a clean jar. Serve over ice, dilute with water or milk to taste, and store the rest in the fridge.

In addition, store-bought cold brew bags or filter pouches make this even easier. Drop the bag in, steep, and remove. No straining required.

Cold Brew Ratios: Ready-to-Drink vs Concentrate

Different ratios produce different results. Furthermore, choose your ratio based on how you want to serve the cold brew:

1:10 (100g coffee to 1 litre water). The classic ready-to-drink ratio. Pour over ice and drink as is.
1:8 (125g coffee to 1 litre water). A stronger ratio. Produces a concentrate that you can dilute with water or milk to taste.
1:5 (200g coffee to 1 litre water). A heavy concentrate. Moreover, this is best for diluting with milk or making cold brew cocktails.

If you’re not sure which to start with, the 1:10 ratio is the safest bet. Consequently, you get a balanced, drinkable cold brew without needing to dilute.

Which Beans Are Best for Cold Brew?

Almost any specialty coffee can make excellent cold brew. However, certain styles work especially well because of how cold extraction shapes flavour:

Naturals and anaerobics. Produce sweet, fruit-forward cold brew with notes of berry, tropical fruit, and chocolate. Moreover, our Ecuador: Mitad del Mundo (Natural) works beautifully here.
Honey-processed coffees. Naturally sweet and balanced. Furthermore, they produce a smooth, dessert-like cold brew.
Brazilian and Central American washed. Chocolate, nut, and caramel-forward. As a result, they produce classic cold brew profiles ideal for milky drinks.
Co-fermented blends. Pronounced flavour amplified further by cold extraction. In addition, our Tutti Frutti Co-Fermented Premium Blend produces an extraordinarily fruity cold brew.

To understand more about processing methods, read our complete guide to coffee processing.

Cold Brew Troubleshooting

If your cold brew doesn’t taste right, the fix is usually a small adjustment. Moreover, here are the most common problems and solutions:

Too weak or watery. Increase the coffee dose, steep for longer, or use a finer (but still coarse) grind.
Too bitter or harsh. Reduce steep time, use a coarser grind, or try a lighter or medium roast. For more, read our guide on why coffee tastes bitter.
Sour or sharp. Increase steep time, use slightly more coffee, or use a finer grind. Furthermore, see our guide on why coffee tastes sour.
Gritty or muddy. Use a coarser grind and strain through both a mesh strainer and a paper filter for a cleaner cup.
Flat or lifeless. Use fresher coffee, ideally roasted within the last 4 to 6 weeks. In addition, check that your water is filtered.

For more on how water shapes coffee flavour, read our guide to water quality in coffee.

How to Serve Cold Brew

Cold brew is incredibly versatile. Moreover, once you have a batch in the fridge, you have the foundation for dozens of drinks:

Black over ice. The classic way to serve cold brew. Lets you taste the coffee at its purest.
With milk or oat milk. Smooths the cup and brings out chocolate and caramel notes.
As a concentrate. Dilute with water or milk to taste. Furthermore, this is great if you’ve made a stronger 1:8 batch.
Cold brew tonic. Mix cold brew with tonic water over ice. As a result, you get a refreshing, slightly bitter drink with a citrus edge.
Affogato. Pour cold brew over a scoop of vanilla ice cream. In addition, this works particularly well with naturals and co-fermented coffees.

Storing Cold Brew Coffee

Cold brew lasts up to 7 days in the fridge in a sealed container. However, the flavour is best within the first 3 to 4 days. After that, it remains safe to drink but loses some of its complexity. Consequently, it’s worth making smaller, more frequent batches rather than one giant batch you can’t finish.

If you want to make cold brew in bulk, freeze it in ice cube trays. Moreover, cold brew ice cubes are perfect because they don’t water down your cold brew as they melt.

Brewing Cold Brew with Routes

Great cold brew starts with great beans. A Routes Coffee subscription delivers freshly roasted single origins and blends to your door, so you always have the right beans on hand for your next batch. Furthermore, our 1kg bag size is particularly good for cold brew lovers, since you’ll work through coffee faster than with hot brewing alone.

Frequently Asked Questions

What is the best cold brew coffee ratio?

A 1:10 ratio (100g coffee to 1 litre of water) produces a balanced, ready-to-drink cold brew. For a stronger concentrate that you can dilute with water or milk, use a 1:8 ratio. As a result, you get flexibility based on how you want to serve it.

How long should I steep cold brew coffee?

Steep cold brew for 12 to 24 hours in the fridge. Furthermore, longer steeps produce stronger flavour, but going beyond 24 hours can introduce bitter or woody notes.

What is the difference between cold brew and iced coffee?

Cold brew is brewed with cold water over 12 to 24 hours, producing a smooth, low-acid coffee. On the other hand, iced coffee is hot-brewed coffee poured over ice, which preserves more of the original acidity and brightness.

Which coffee beans are best for cold brew?

Medium to medium-dark roasted specialty coffees work best for cold brew. Furthermore, naturals and honey-processed coffees produce sweeter, fruit-forward cold brew, while washed coffees produce cleaner, more structured cups.

How long does cold brew coffee last in the fridge?

Cold brew coffee lasts up to 7 days in the fridge in a sealed container. Moreover, flavour is best within the first 3 to 4 days. After that, it remains safe to drink but loses some of its complexity.

Can I use pre-ground coffee for cold brew?

Pre-ground coffee can work, but it is usually too fine for cold brew, which can lead to over-extraction. As a result, freshly grinding to a coarse, sea-salt texture produces noticeably better results.

Why is my cold brew bitter?

Cold brew turns bitter when steeped too long, ground too fine, or made with stale beans. Moreover, reducing steep time, using a coarser grind, or switching to a fresher batch usually solves the problem.

Does cold brew have more caffeine?

Cold brew typically has more caffeine per millilitre than hot-brewed coffee, especially when made as a concentrate. However, when diluted to drinking strength, the caffeine content is similar to a strong cup of hot coffee.