Cold Brew Calculator
Cold Brew Calculator
How much finished cold brew do you want to make?
Optional: Cost Per Cup Estimator
Enter Your Batch Details
Choose a desired output volume and brew strength above to see exact coffee grounds, water amounts, steep time, caffeine, and cost per cup.
Perfect ratios, steep times, and caffeine estimates for every batch
Cold brew coffee has become one of the most popular ways to enjoy coffee — smoother, less acidic, and remarkably easy to make at home. The challenge is getting the recipe right. Too much coffee and your brew is unbearably bitter; too little and it tastes watery and flat. The cold brew calculator takes the guesswork out of the process by computing the exact amount of coffee grounds and water you need for any batch size, based on your chosen strength and the industry-standard 20% water absorption factor. Unlike drip coffee, cold brew is steeped in cold or room-temperature water for an extended period — typically 8 to 24 hours. This slow extraction produces a concentrate or ready-to-drink beverage with a naturally sweeter, chocolatey profile and lower perceived acidity. The ratio of coffee to water is the single most important variable in cold brew, and it determines not just the flavor but also the caffeine content, the steep time required, and whether you need to dilute the result before drinking. The four standard strength presets — Mild (1:12), Regular (1:8), Strong (1:6), and Concentrate (1:4) — cover the full range of cold brew styles. A 1:12 ratio produces a light, refreshing cup you can drink straight from the pitcher. A 1:8 ratio is the everyday workhorse: strong enough to taste substantial but mellow enough to enjoy on its own over ice. A 1:6 ratio sits at the edge between ready-to-drink and concentrate territory, ideal if you prefer bold cold brew or want flexibility to add milk without losing flavor. The 1:4 concentrate is brewed for dilution — one part concentrate plus one part water (or milk) delivers a 1:8 final ratio, doubling the number of servings from the same batch. One detail that most home brewers overlook is water absorption. Coffee grounds absorb approximately 20% of the water they are steeped in, so if you want one liter of finished cold brew, you actually need to start with about 1.25 liters of water. This calculator applies that correction automatically — every water measurement shown already accounts for absorption loss, so you always end up with the yield you actually want. Steep time depends on two things: the strength you are targeting and where you are brewing. In the refrigerator, cold temperatures slow extraction, so you need more time — typically 10 to 24 hours depending on strength. At room temperature, extraction happens faster, cutting steep time to 6–16 hours. The calculator shows a range rather than a single number because variables like grind coarseness, bean origin, and water quality all influence the final extraction speed. Taste your brew at the lower end of the range; if it needs more time, steep in 1-hour increments until it reaches your preferred flavor. Caffeine content in cold brew is often misunderstood. Because the grounds-to-water ratio is higher than drip coffee and the extraction is long, cold brew can be quite caffeinated — especially concentrate. This calculator estimates caffeine by applying the standard figure of approximately 12 mg of caffeine per gram of Arabica coffee grounds, then distributing that total across the number of servings in the batch. The result is an estimate; actual caffeine varies with roast level (lighter roasts retain slightly more caffeine), bean variety, and exact steep time. For anyone tracking their coffee budget, the optional cost estimator shows you exactly how much each cup costs based on your bag price and bag weight. Cold brew is notoriously economical when brewed at home — a typical batch of eight servings often costs under $2 total — which makes the per-cup cost comparison against cafe prices particularly eye-opening. Whether you are making a quart for the week, a gallon for a gathering, or experimenting with concentrate for the first time, this calculator gives you the precise measurements, timing guidance, and nutritional context you need to brew consistently excellent cold brew every time.
Understanding Cold Brew Ratios
What Is Cold Brew Coffee?
Cold brew coffee is made by steeping coarsely ground coffee in cold or room-temperature water for an extended period, typically 8 to 24 hours, then filtering out the grounds. Unlike hot brewing methods that extract flavor with heat in a matter of minutes, cold brew relies on time and a large volume of water relative to the grounds. The result is a coffee concentrate or ready-to-drink beverage with a smooth, naturally sweet flavor and noticeably lower acidity compared to hot-brewed coffee. Cold brew is not the same as iced coffee, which is hot coffee poured over ice — cold brew is brewed cold from start to finish, producing a fundamentally different chemical extraction profile that many coffee drinkers find gentler on the stomach and more refreshing in warm weather.
How Are the Amounts Calculated?
The core formula for cold brew uses the coffee-to-water ratio (expressed as 1:X, where X is the parts of water per part of coffee) and a 20% water absorption correction. Step one: divide your desired output volume by 0.8 to find the actual water you need to add (since grounds absorb roughly 20% of the water). Step two: divide that water volume by the ratio to find the coffee weight in grams (because 1 mL of water weighs approximately 1 gram). For example, to make 946 mL (1 quart) of regular-strength cold brew at a 1:8 ratio: water needed = 946 / 0.8 = 1,183 mL; coffee needed = 1,183 / 8 = 148 g. Caffeine is estimated at 12 mg per gram of Arabica grounds, distributed evenly across the number of servings.
Why Does the Ratio Matter So Much?
The coffee-to-water ratio is the primary lever controlling flavor, caffeine, and dilution behavior in cold brew. A ratio that is too low (too much water relative to coffee) produces a weak, under-extracted brew that tastes thin and sour. A ratio that is too high (too much coffee relative to water) can lead to a syrupy, over-extracted concentrate that is unpleasant to drink straight and must be heavily diluted. Getting the ratio right also directly controls your caffeine intake — shifting from 1:12 to 1:8 roughly doubles the caffeine per serving. For concentrate users, the ratio also determines how much you dilute at serving time, with a 1:4 concentrate typically diluted 1:1 with water or milk to achieve a drinking-strength beverage around 1:8.
Limitations and Variables
This calculator provides excellent estimates based on industry-standard averages, but several real-world variables can shift the actual results. The 20% water absorption figure is typical for coarsely ground coffee but can range from 15% to 25% depending on grind size, bean density, and roast level. The caffeine estimate uses 12 mg/g for Arabica, but Robusta beans contain roughly twice as much caffeine (~25 mg/g), and even within Arabica, lighter roasts retain fractionally more caffeine than darker roasts. Steep time ranges are guidelines — your local water chemistry, ambient temperature during room-temperature brewing, and how fresh your beans are all affect extraction speed. Always taste-test near the low end of the steep time range and adjust accordingly. The first batch with a new coffee or ratio is always a calibration brew.
How to Use the Cold Brew Calculator
Set Your Batch Size and Units
Choose Metric or Imperial, then enter the total volume of cold brew you want to make — for example, 946 mL (1 quart), 1893 mL (half-gallon), or 4 cups. This is your target finished yield, not the water you will add.
Pick Your Brew Strength
Select Mild (1:12) for a light, refreshing ready-to-drink brew, Regular (1:8) for everyday cold brew, Strong (1:6) for a bold cup, or Concentrate (1:4) to make a batch that you dilute before serving. Use Custom to enter any ratio you prefer.
Choose Brew Location and Read Steep Time
Select Refrigerator or Room Temperature. Fridge brewing takes longer (10–24 hours) but is safer for longer unattended steeps. Room temperature is faster (6–16 hours) but requires monitoring. The calculator shows the recommended time range for your chosen strength and location.
Optionally Add Coffee Price for Cost Per Cup
Enter the price you paid for your coffee bag and the bag weight to see the exact cost per cup. This is optional — leave it blank if you only need the recipe measurements. Hit Print to save your recipe for easy reference while brewing.
Frequently Asked Questions
Why does the calculator ask for output volume instead of water volume?
Most people think about how much cold brew they want to end up with — a quart for the week, a half-gallon for a gathering — not how much water to pour in. Because coffee grounds absorb approximately 20% of the water they steep in, starting with the target yield and working backwards gives you the right water amount automatically. If you put in 1 quart (946 mL) as your desired output, the calculator adds the absorption factor and tells you to use about 1,183 mL of water so that after the grounds absorb their share, you are left with close to 1 quart of finished cold brew. This approach avoids the common mistake of using exactly 1 quart of water and ending up with only 3 cups of finished coffee.
What is the best coffee-to-water ratio for cold brew?
The most widely recommended ratio for everyday cold brew is 1:8 — one part coffee grounds to eight parts water by weight. This produces a brew that is strong and flavorful on its own over ice, with a caffeine level roughly comparable to a cup of drip coffee. If you prefer a lighter, more refreshing cup similar to iced tea in body, try 1:12. For a concentrated base that you dilute before drinking (which is more economical since one batch makes more servings), use 1:4 to 1:6. There is no single correct answer — the right ratio is the one that tastes best to you, and this calculator makes it easy to experiment by letting you plug in any custom ratio alongside the standard presets.
How long should I steep cold brew?
Steep time for cold brew depends on two factors: the strength you are making and where you are brewing. In the refrigerator, the cold temperature slows extraction, so mild cold brew needs 10–12 hours, regular needs 14–16 hours, strong needs 18–22 hours, and concentrate needs 20–24 hours. At room temperature, extraction is faster: mild takes 6–8 hours, regular 8–12 hours, strong 10–14 hours, and concentrate 12–16 hours. These are ranges, not exact targets. Always taste your cold brew at the low end of the range. If it is too weak or sour, steep for another hour and taste again. Over-steeped cold brew can become bitter and astringent, especially at room temperature.
How much caffeine is in cold brew?
Cold brew caffeine content is often misunderstood. The calculator estimates caffeine at approximately 12 mg per gram of Arabica coffee grounds — the most common bean type sold commercially. Total caffeine across the batch is divided by the number of servings to give a per-cup estimate. A standard 8 fl oz (240 mL) serving of regular-strength cold brew (1:8) typically contains 150–200 mg of caffeine, though this varies significantly with bean origin, roast level, and steep time. Concentrate brewed at 1:4 will show a higher per-serving caffeine figure because serving size is calculated at 120 mL pre-dilution. After diluting concentrate 1:1, the caffeine per 240 mL serving aligns more closely with a regular brew. Robusta beans (some espresso blends) contain roughly double the caffeine of Arabica.
Why must I use a coarse grind for cold brew?
Cold brew steeps for many hours, and a fine or medium grind exposes far more surface area to the water over that extended time. This leads to over-extraction, producing a brew that is excessively bitter, astringent, and harsh-tasting — the opposite of the smooth, mellow flavor cold brew is prized for. A coarse grind (similar to what you would use in a French Press) slows extraction to a pace that matches the long steep duration, allowing the water to draw out the desirable sweet and chocolatey compounds without pulling the harsher bitter ones. A coarse grind is also much easier to filter at the end of steeping. Fine or medium grounds clog paper and mesh filters, making straining slow and messy.
How long does cold brew last in the refrigerator?
Properly stored cold brew keeps for up to 2 weeks in the refrigerator in a sealed container such as a mason jar, pitcher, or bottle. Concentrate lasts equally well — the higher coffee concentration actually makes it slightly more resistant to spoilage. Undiluted concentrate is best diluted just before serving rather than stored pre-diluted, since the diluted version degrades somewhat faster in flavor. Cold brew brewed at room temperature should be refrigerated as soon as steeping is complete and should be consumed within the same 2-week window. You can tell cold brew has gone bad if it smells sour, vinegary, or has developed an off-taste; freshly brewed cold brew should smell pleasantly of coffee with no fermented or sharp odors.