Cold Brew Coffee: Everything You Need to Know

Cold brew is one of the easiest and most rewarding ways to make coffee at home. No expensive equipment, no precise timing, and the result is a smooth, low-acid concentrate that keeps in the fridge for up to two weeks. Whether you drink it black over ice, diluted with milk, or warmed up on a cold morning, cold brew is endlessly versatile.

This guide covers everything: what cold brew actually is, how it differs from iced coffee, the right ratio and steep time, three ways to make it at home, how to serve it, and the most common mistakes to avoid.

What Is Cold Brew Coffee?

Cold brew is made by steeping coarsely ground coffee in cold or room-temperature water for an extended period, typically 12 to 24 hours. Unlike hot coffee, no heat is used at any point in the process. The result is a concentrated coffee liquid that is naturally sweeter, smoother, and significantly less acidic than hot-brewed coffee.

The absence of heat means the acidic compounds that hot water extracts from coffee grounds are largely left behind. Cold brew has up to 60% less acidity than hot-brewed coffee, which makes it a popular choice for people with sensitive stomachs or acid reflux.

Cold Brew vs Iced Coffee: What's the Difference?

Iced coffee is simply hot-brewed coffee that has been cooled and poured over ice. It retains all the acidity of hot coffee and tends to taste diluted as the ice melts. It is quick to make but lacks the smoothness of cold brew.

Cold brew is brewed from scratch using cold water over many hours. It is more concentrated, smoother, less acidic, and has a naturally sweeter flavour. It takes more planning but produces a noticeably superior result.

Why Cold Brew?

Lower acidity: Up to 60% less acidic than hot coffee, making it ideal for people with acid reflux or sensitive stomachs. For more on coffee acidity, see: Is Coffee Acidic? pH Levels and How to Reduce Acidity.

Naturally sweeter: Cold water extracts fewer bitter compounds, so cold brew tastes smoother and sweeter without added sugar.

Higher caffeine: Because cold brew is a concentrate, it contains more caffeine per millilitre than standard hot coffee. Dilute to taste.

Make ahead: One batch lasts up to two weeks in the fridge, making it the most convenient daily coffee option for busy mornings.

Versatile: Serve over ice, dilute with water or milk, warm it up, use it in cocktails, or add it to smoothies.

Coffee to Water Ratio

The standard cold brew ratio is 1:8 (coffee to water by weight) for a concentrate, or 1:15 for a ready-to-drink strength. Most home brewers make a concentrate and dilute it to taste when serving.

When serving, dilute concentrate with equal parts water or milk (1:1) for a standard strength cup. Adjust to taste.

How to Make Cold Brew at Home

What you need: Freshly roasted coffee beans, burr grinder, kitchen scale, large mason jar or container with lid, fine mesh strainer or cheesecloth, cold filtered water.

Method 1: Mason Jar (Simplest)

Step 1: Weigh out 80g of coffee and grind coarsely. A coarse grind is essential. Fine grounds over-extract and produce a bitter, muddy concentrate.

Step 2: Add the grounds to a large mason jar and pour over 1 litre of cold filtered water. Stir to make sure all the grounds are saturated.

Step 3: Seal the jar and place in the fridge. Steep for 12-18 hours. For a stronger concentrate, steep up to 24 hours.

Step 4: Strain through a fine mesh strainer lined with cheesecloth or a paper coffee filter into a clean jar. Do not press or squeeze the grounds. Let it drain naturally for the cleanest result.

Step 5: Store the concentrate in the fridge for up to 2 weeks. Dilute and serve as needed.

Method 2: French Press

Step 1: Add 80g of coarsely ground coffee to your French press.

Step 2: Pour over 1 litre of cold filtered water and stir. Place the lid on with the plunger pulled up (do not press down yet).

Step 3: Steep in the fridge for 12-18 hours.

Step 4: Slowly press the plunger down and pour the concentrate through a paper filter into a storage jar to remove fine sediment.

Method 3: Toddy Cold Brew Maker

Add 250g of medium-coarse ground coffee to the Toddy bucket and pour over 1 litre of cold water in a slow circular motion to saturate all the grounds. Steep for 12 hours, then remove the stopper and allow the concentrate to drain into the glass decanter. Clean and simple.

How to Serve Cold Brew

Over ice (classic): Fill a glass with ice, add cold brew concentrate, and dilute with equal parts cold water. Add milk or a milk alternative for a creamier result.

Cold brew latte: Pour concentrate over ice and top with oat milk, almond milk, or whole milk. No frothing needed.

Hot cold brew: Add concentrate to a mug and top with hot water or steamed milk. The flavour is noticeably smoother than standard hot coffee.

Cold brew soda: Mix concentrate with sparkling water over ice for a refreshing, lightly caffeinated drink.

For milk alternative pairing ideas, see: Best Milk Alternatives for Lattes: Oat, Almond and Macadamia Compared.

Common Mistakes to Avoid

Grind too fine: Fine grounds over-extract and produce a bitter, muddy concentrate. Always use a coarse grind.

Not steeping long enough: Under 12 hours and the concentrate will be weak and watery. 12-18 hours is the sweet spot for most beans.

Squeezing the filter: Pressing or squeezing the cheesecloth forces bitter compounds and fine particles into the concentrate. Let it drain naturally.

Using tap water: Chlorine and minerals in tap water affect the flavour. Always use cold filtered water.

Steeping at room temperature too long: Room temperature steeping is fine for 12-18 hours, but beyond that the risk of bacterial growth increases. Always move to the fridge once steeping is complete.

Frequently Asked Questions

How long should you steep cold brew?

The ideal steep time is 12-18 hours in the fridge. For a stronger concentrate, steep up to 24 hours. Under 12 hours produces a weak, watery result. Over 24 hours can make the concentrate taste bitter and over-extracted.

What is the best coffee to water ratio for cold brew?

For a concentrate, use 1:8 (80g coffee to 1 litre of water). Dilute with equal parts water or milk when serving. For a ready-to-drink strength, use 1:15.

What grind size is best for cold brew?

Always use a coarse grind. Fine grounds over-extract during the long steep and produce a bitter, muddy concentrate. Use a burr grinder for consistent particle size.

How long does cold brew last in the fridge?

Cold brew concentrate keeps well in a sealed jar in the fridge for up to 2 weeks. Ready-to-drink cold brew (already diluted) is best consumed within 3-4 days.

Is cold brew stronger than regular coffee?

Cold brew concentrate is significantly stronger than regular coffee. When diluted 1:1 with water or milk, it is roughly equivalent in strength to a standard cup of coffee. The caffeine content depends on how much you dilute it.

Can you make cold brew with any coffee beans?

Yes, though medium to dark roast Arabica beans tend to produce the smoothest, most balanced cold brew. Light roasts can taste thin and sour in cold brew. Always use freshly roasted whole beans and grind just before brewing.