How to Make Cold Brew Coffee at Home: Smooth, Low-Acid Results Every Time

Cold brew is one of the most forgiving, rewarding brews you can make at home — and it requires almost no special equipment. If you have a jar, a coffee filter, and patience, you can produce a smooth, naturally sweet concentrate that beats any bottled cold brew on the market. The secret is time, not temperature. By steeping coarsely ground coffee in cold or room-temperature water for 12 to 24 hours, you extract all the pleasant sweetness and chocolate-like body without ever triggering the acidic compounds that hot brewing releases. The result is a coffee that is up to 67% less acidic than hot-brewed coffee — meaning it is gentler on your stomach, your teeth, and your taste buds.

This guide covers everything you need to know: the correct grind size, the ideal coffee-to-water ratio, how long to steep, how to filter without buying anything extra, how to store your concentrate, and when to dilute it. Whether you are making a single serving or a week's worth of coffee in one batch, the method is the same. Let's get into it.

What You Need

You do not need a dedicated cold brew maker to produce excellent results, but having one certainly makes the process cleaner and more repeatable. Here is the full equipment list:

• Coarsely ground coffee — 100g for a standard batch
• Filtered water — 800ml (cold or room temperature)
• A large jar, pitcher, or dedicated cold brew maker — at least 1 litre capacity
• A fine mesh strainer or paper coffee filter — for filtering
• A kitchen scale — for accurate ratios
• A refrigerator — for cold steeping

Getting the Grind Size Right

Grind size is the single most important variable in cold brew. You want a coarse grind — comparable to what you would use for a French press. Think coarse sea salt or raw sugar crystals. The large particle size slows extraction, which is exactly what you want when water has 12 to 24 hours to do its work. If you grind too fine, over-extraction happens fast, producing a bitter, muddy, unpleasant brew. Too coarse and you get a thin, watery result that lacks body and sweetness.

On most burr grinders, a coarse cold brew setting sits at the high end of the grind range — around 7 to 9 on a Baratza Encore (which goes to 40), or the highest two or three settings on most entry-level grinders. If you are using a blade grinder, pulse briefly and stop well before you reach anything resembling a fine powder. Ideally, invest in a hand burr grinder like the Timemore C2 for consistent coarse grinding without spending a fortune.

The Coffee-to-Water Ratio

The standard cold brew concentrate ratio is 1:8 by weight — meaning for every 1 gram of coffee, you use 8 grams (8ml) of water. A practical batch looks like this:

This 1:8 ratio produces a concentrate, not a ready-to-drink coffee. You will dilute it before serving. If you prefer to brew directly to drinking strength (bypassing the concentrate step), use a 1:15 ratio — 100g coffee to 1500ml water — and steep for the same duration. The concentrate method is more popular because it takes up less fridge space and you can adjust dilution to preference each time you pour.

Step-by-Step Instructions

1. Weigh your coffee and water. Use a kitchen scale. For a standard batch, measure out 100g of whole beans and 800ml of filtered water. Precision matters more than you think — eyeballing leads to inconsistent results from batch to batch.
2. Grind your coffee coarsely. Set your grinder to a coarse French press setting. Grind all 100g and collect the grounds. Give the grounds a quick visual check — you should see chunky, irregular particles, not a fine powder.
3. Combine coffee and water. Add the ground coffee to your jar or cold brew maker. Pour the 800ml of cold, filtered water over the grounds slowly, making sure all the grounds are saturated. Stir gently once with a long spoon to ensure even contact between water and coffee.
4. Cover and refrigerate. Place a lid, plastic wrap, or a coffee filter secured with a rubber band over the top of your jar. Transfer to the refrigerator. Alternatively, steep at room temperature for a faster extraction (8–12 hours is sufficient at room temperature vs. 16–24 in the fridge).
5. Steep for 12 to 24 hours. The sweet spot for fridge steeping is 16 to 18 hours for most coffees. At 12 hours you get lighter, brighter notes. At 24 hours the brew becomes heavier and more intense. Experiment to find your preference.
6. Filter the concentrate. Once steeping is done, filter the brew through a paper filter, fine mesh strainer, or a dedicated cold brew maker's built-in filter. Do not press or squeeze the grounds — let gravity do the work. Pressing forces out bitter compounds.
7. Transfer to a clean container. Pour the filtered concentrate into a clean glass jar or pitcher. Seal tightly and refrigerate. Your cold brew is ready to use immediately.

Filtering Your Cold Brew

How you filter cold brew affects both clarity and body. There are two primary options:

Paper filters produce the cleanest, clearest concentrate. They remove fine particles and oils, resulting in a lighter-bodied but very smooth cup. Use a standard pour-over paper filter (Chemex, V60, or basket filter) placed in a mesh strainer over a large jug. Pour the steep through slowly. One filter pass is usually enough; for very clear concentrate, pass it through a second paper filter.

Metal mesh filters (like those in the Hario Mizudashi or a French press) allow more of the coffee's natural oils through, producing a richer, fuller-bodied concentrate. This is often preferred for cold brew used in milk-based drinks. The trade-off is a slightly cloudier result and some fine sediment at the bottom of your jar.

Concentrate vs. Ready-to-Drink

Cold brew concentrate is typically 2 to 2.5 times stronger than regular coffee. Before drinking, dilute it:

• 1:1 dilution (equal parts concentrate and water or milk) — produces a strong, bold cup similar to strong drip coffee.
• 1:2 dilution (one part concentrate to two parts liquid) — produces a medium-strength cup closer to standard drip coffee.
• Over ice — always dilute slightly more than you think, because melting ice continues to water down the drink. Start with a 1:1.5 ratio over ice.

Storage and Shelf Life

Properly made cold brew concentrate stored in a sealed glass container in the refrigerator lasts up to two weeks. This is one of its greatest practical advantages — you make a large batch on a Sunday and have coffee for the entire week with zero morning effort.

Once diluted with milk or water, consume the drink within 24 hours. Do not store diluted cold brew for multiple days as the quality degrades quickly and dairy can spoil. The concentrate itself, however, is remarkably shelf-stable due to its very low oxidation rate in the fridge.

Troubleshooting

Cold brew tastes bitter or harsh: Your grind is too fine, or you steeped for too long. Try a coarser grind setting and reduce steep time to 14–16 hours. Also check your water — overly hard or chlorinated tap water can contribute off-flavors.

Cold brew tastes sour or underdeveloped: You under-extracted. Either your grind was too coarse, your steep time was too short, or your ratio was too low. Try 18+ hours and check your grind size is genuinely coarse.

Cold brew is very cloudy: Normal if you used a metal filter. For clearer results, filter twice through a paper filter. Cloudiness does not affect taste significantly but affects visual appeal.

Cold brew tastes weak or watery: Your ratio is off. Make sure you are weighing your coffee and water rather than using volume measurements. Add more coffee next batch (try 120g per 800ml) or reduce dilution when serving.

Pro Tips

Recommended Gear