How to Make Cold Brew With a Mason Jar – Step-by-Step Guide

Let’s be honest—on a very warm day, a hot cup of coffee feels like punishment.

You want something cold, smooth, and bold.

You’ve heard about cold brew. You’ve seen the fancy bottles. But here’s the secret: you don’t need a special brewer. You just need a mason jar.

Yup. That same jar you used for overnight oats or to store nuts now has a much better job—making delicious cold brew.

It’s dead simple. No gadgets, no espresso background needed. Just good coffee, cold water, and a little patience.

And if you think cold brew is a trendy new thing, it’s actually not.

The history of cold brew goes back hundreds of years—some say as far back as 1600s Japan.

Alright, let’s skip the fluff and get to work.

What You’ll Need

• One mason jar (at least 500 ml, but 1 liter is better)
  
  
• Fresh coffee beans, coarsely ground (breadcrumb consistency)
  
  
• Cold, filtered water
  
  
• Spoon or stir stick
  
  
• A paper filter, cheesecloth, or clean cloth (for filtering)
  
  
• A second jar or carafe
  
  

That’s it.

Coffee-to-Water Ratio

Use a 1:8 ratio of coffee to water.

For example:

• 50 grams of coffee
  
  
• 400 ml of water
  
  

This makes a strong concentrate. You can dilute it later.

Step-by-Step Guide: Cold Brew in a Mason Jar

1. Grind Your Beans

Use coarse ground coffee. Like sea salt or breadcrumbs. Too fine, and it’ll over-extract and taste bitter. Too coarse, and it’ll taste weak.

2. Add Coffee to Your Jar

Drop the ground coffee into the mason jar. If you don’t have a scale, about 7–8 heaping tablespoons equals 50 grams.

3. Add Cold Water

Pour the water slowly over the coffee. Stir to make sure everything is saturated. No dry pockets.

4. Let It Steep

Seal the jar and let it sit:

• In the fridge for 16 to 24 hours
  
  
• At room temperature for 12 to 16 hours
  
  

Longer steeping makes it stronger. Don’t go over 24 hours—it’ll turn bitter.

5. Filter the Coffee

Pour the brew through a filter into another jar. You can use:

• A fine mesh strainer with a paper filter
  
  
• A clean cloth or T-shirt
  
  
• A proper cold brew bag
  
  

Take your time. Don’t press or squeeze—it’ll make the brew taste harsh.

Serving Your Cold Brew

Now that you’ve got a smooth concentrate, here’s what you can do with it:

• Drink it straight (if you like strong coffee)
  
  
• Dilute it 1:1 with water or milk
  
  
• Serve it over ice
  
  
• Try cold brew with tonic water for a fizzy twist
  
  

Cold brew keeps in the fridge for up to a week.

Cleaning Up

Clean your jar right away. Don’t leave the used grounds inside. Trust me—it gets gross fast.

FAQ

How coarse should my coffee be?

Use a coarse grind. Like breadcrumbs or sea salt. Finer grinds clog your filter and turn the brew bitter.

Can I use pre-ground coffee?

You can, but it’s not ideal. It’s usually too fine and not as fresh. You’ll get more sediment and less flavor. Freshly ground is always better.

How long does cold brew last?

Cold brew lasts up to 7 days in the fridge. After that, it starts losing flavor. If it tastes sour or musty, toss it.

What kind of coffee should I use?

Medium or dark roast works great. You’ll get chocolatey, nutty flavors.

Light roasts work too, but they’re more acidic and fruity. 

Do I need to dilute cold brew?

Not necessarily. But it is strong. A good starting point is 1:1 with water or milk. Taste and adjust as needed.

Conclusion

You don’t need expensive gear or special tools. A mason jar does the job just fine. It’s all about using good beans, getting the grind right, and waiting it out.

Once you’ve nailed the basics, you can experiment—different beans, different ratios, different steep times.

That’s the fun part.

Cold brew is forgiving, and it always feels like a treat.