Cold Brew Coffee-to-Water (Ratio Guide)

For ready-to-drink cold brew, start with 1 part coarse-ground coffee to 15 parts water by weight, such as 50 g coffee and 750 g water. For a stronger concentrate, start at 1:8, then dilute after filtering. Steep for 12–18 hours, filter, and keep the finished brew covered in a refrigerator at 4°C / 40°F or colder.

Do you want coffee ready to pour on a busy morning, or a stronger batch you can dilute to suit each cup? The right coffee-to-water ratio depends on that choice. Weighing both ingredients makes it easy to repeat a batch and adjust its strength without guessing.

I use 1:15 as a practical starting point for ready-to-drink cold brew and 1:8 for concentrate. These are ratios by mass, not volume: weigh the coffee and water in grams. Grind size, steep time, and dilution also affect the result, so keep those steps steady while you find your preferred flavor.

Choose a Food-Safe Vessel and Set the Coffee-to-Water Ratio

A cold-brew ratio compares the weight of dry coffee with the weight of water. Start at 1:15 for a brew intended to drink as made, or 1:8 for concentrate. Use a clean, food-safe vessel and potable water, then adjust the strength after tasting.

A kitchen scale gives more consistent results than scoops. Coffee beans and grounds can take up different amounts of space, so a volume measure may not give the same coffee weight from one batch to the next. For these ratios, each number represents a unit of mass.

These are starting points, not a promise that every coffee will taste the same. Bean type, grind, and steeping conditions can change the cup. Keep a short record of the ratio, grind, steep time, and result so you can repeat a batch you like.

Choose a clean vessel made of glass, stainless steel, or suitable food-grade plastic. These materials work for ordinary cold brewing. Avoid prolonged contact between the brew and unlined reactive metal. Wash your hands, vessel, filter, and utensils before starting, and use potable water.

For an example ready-to-drink batch, weigh 50 g of coarse-ground coffee and 750 g of water. For concentrate, use 100 g of coffee and 800 g of water. If your vessel is small, scale both weights down while keeping the same ratio.

Steep, Filter, and Dilute for Consistent Strength

Steeping is the time coffee grounds sit in water to extract flavor and strength. A coarse, reasonably even grind and a consistent steep help make batches easier to compare. For a controlled home method, steep for 12–18 hours in the refrigerator at 4°C / 40°F or colder.

1. Weigh the coffee and water separately.
2. Add the grounds to the clean vessel.
3. Pour in the water evenly, making sure all the grounds get wet.
4. Cover the vessel and steep for 12–18 hours under refrigeration.
5. Pour the brew through a suitable coffee filter into a clean container.

A coarse grind is a useful starting point because it is easier to filter cleanly than a very fine grind. If the grounds are uneven, the brew may be harder to filter consistently. Avoid squeezing the grounds if you want less sediment in the finished drink.

Steep time and grind both affect extraction, so change one at a time when adjusting a batch. If the brew tastes too strong, add water after filtering. If it tastes too weak, try a stronger coffee-to-water ratio next time or adjust the grind slightly, then keep the rest of your method steady.

For concentrate, weigh the added water so you can repeat the dilution. A 1:8 brew mixed with an equal mass of water gives an approximate overall ratio of 1:16, based on the coffee and water used. For example, add 800 g of water to concentrate made with 100 g coffee and 800 g water. The final amount of liquid may be lower than the input water because the grounds retain some liquid.

Clean Equipment and Refrigerate Cold Brew Safely

Cold brewing does not pasteurize coffee or make it shelf-stable. Keep filtered brew covered in a refrigerator at 4°C / 40°F or colder, and use it within 3–4 days for quality and conservative handling. Refrigeration is a key part of the home process, not an optional finishing step.

After filtering, transfer the brew to a clean, covered container and refrigerate it promptly. Do not treat the coffee’s acidity, smell, or taste as proof that it is safe after being stored at room temperature. Cold extraction is not a pathogen-kill step.

If the brew has signs of spoilage or you are unsure how long it was held outside safe refrigeration, discard it. Do not rely on a familiar recipe or a strong coffee ratio to make up for uncertain storage conditions. Commercial production needs a validated food-safety plan and shelf life; a home method does not establish either one.

Wash the vessel, filter, and utensils after use. Clean equipment before starting the next batch, rather than assuming that a quick rinse is enough. This keeps residue from carrying over and makes your next ratio and flavor easier to assess.

Serve Chilled and Adjust the Cup to Taste

The brew ratio sets the strength of the batch, while the amount of water or milk in the cup sets the strength of the drink you serve. Start with a measured batch, taste it chilled, then adjust in small steps. This lets you separate brewing changes from serving preferences.

For ready-to-drink cold brew, serve it chilled or over ice. Ice can melt and dilute the drink, so taste it as served before changing the next batch. If you prefer milk or another addition, add it to the cup rather than changing the whole batch at once.

For concentrate, begin with an equal mass of water, then taste and adjust. This equal-mass dilution is a repeatable starting point, not a rule for every palate. Keep a note of how much water you add so you can make the same cup again.

A useful home record can be simple: coffee mass, water mass, grind description, steep time, and any dilution at serving. If one batch tastes different, those notes help you identify what changed instead of shifting several variables at once.

Common Batch Scenarios and a Simple Routine

A batch scenario shows how the same method can fit different needs without changing its basic controls. The examples below use the same ratios and process, scaled to common home situations. Choose the amount you need, weigh both ingredients, and keep the steep and storage steps consistent.

• One or two servings: Use 25 g coffee and 375 g water at 1:15. Filter and serve chilled.
• A larger ready-to-drink batch: Use 100 g coffee and 1,500 g water at 1:15.
• A small concentrate batch: Use 50 g coffee and 400 g water at 1:8. Dilute after filtering.
• A taste adjustment: Keep the same recipe, then add water to the cup or batch in measured amounts.

These are scaled examples, not guaranteed serving counts. Cup size, ice, and personal preference change how many drinks a batch makes. Also, the filtered liquid may weigh less than the starting water because coffee grounds hold some of it.

For a repeatable routine, clean the equipment, weigh ingredients, wet all grounds, cover and refrigerate for 12–18 hours, then filter into a clean container. Refrigerate the finished brew promptly. Once you have a version you enjoy, record it and change only one variable at a time.

Cold Brew Ratio FAQs

These quick answers cover the main choices: how much coffee and water to weigh, how to make concentrate, and how to steep and store the finished brew. Use the ratios as starting points, then adjust to taste while keeping refrigeration and clean equipment in place.

What is a good coffee-to-water ratio for cold brew?
Start at 1:15 by weight for ready-to-drink cold brew. For example, use 50 g coffee with 750 g water.

What ratio should I use for cold-brew concentrate?
Start at 1:8 by weight, such as 100 g coffee with 800 g water. Filter it, then dilute to taste.

Should I measure coffee and water by weight or volume?
Weigh both in grams for repeatable results. Scoops can hold different amounts of coffee, so volume measures may vary.

How much water do I add to 1:8 concentrate?
An equal mass of water is a useful starting point. For concentrate made with 100 g coffee and 800 g water, try adding 800 g water after filtering.

How long should cold brew steep?
Steep for 12–18 hours under refrigeration at 4°C / 40°F or colder. Keep the time consistent when comparing batches.

What grind works best for cold brew?
Use a coarse, reasonably even grind. Very fine grounds can be harder to filter cleanly.

Can I steep cold brew at room temperature?
A controlled room-temperature process is possible, but cold brewing does not pasteurize the coffee. Refrigerated steeping is the recommended home starting method; refrigerate the finished brew promptly.

How long does homemade cold brew last?
Keep it covered at 4°C / 40°F or colder and use it within 3–4 days for quality and conservative handling.

Can I leave cold brew on the counter because it is acidic?
No. Do not assume acidity makes it safe at room temperature. Cold brew is not shelf-stable by default.

Why is my cold brew weaker than expected?
Check your measured ratio, grind, and steep time. For the next batch, weigh ingredients and change one factor, such as moving from 1:15 to 1:12.

For a dependable first batch, weigh 50 g of coarse coffee and 750 g of potable water, steep covered in the refrigerator for 12–18 hours, and filter into a clean container. Keep it refrigerated, taste it chilled, and adjust the next batch by changing one measured step at a time.

(This article was written by one of our staff writers, Daniel M. Whitaker. Visit our Meet the Team page.)