What ratio for cold brew coffee?
Quick answer
For concentrate, use 1:8 by weight — e.g. 60 g coffee to 480 ml chilled water. Steep 12–18 hours in a fridge at 4 °C or below, strain, then dilute 1:1 with water or milk before drinking. Ready-to-drink cold brew is closer to 1:12–1:15.
What you need
- Container — a 1-liter mason jar, a French press, or any vessel that holds liquid and can be covered. Wide-mouth mason jars are easiest to clean.
- Scale — measuring by weight is more consistent than scoops.
- Grinder — set to extra coarse (like coarse sea salt). Pre-ground works in a pinch; just use coarser than you'd use for drip.
- Filter — a fine-mesh strainer lined with a paper coffee filter, a cheesecloth, or just the French press plunger. Paper filters give the clearest result.
- Storage pitcher — clean, covered and refrigerated; label the batch date. This recipe does not establish a safe shelf life.
Grind size
Extra coarse is the right target. Think coarse sea salt or roughly twice the size of a typical drip grind. Here's why: cold water extracts slowly. Fine grounds can slow filtration and increase sediment; taste also depends on roast, dose and contact time. An extra coarse grind controls extraction rate, cuts sludge, and makes filtering much easier.
If you only have pre-ground coffee labeled "drip grind," it will still work — start with the same refrigerated process, filter through paper and adjust the next batch by taste.
Step by step
- Coarse grind — extra coarse reduces sludge.
- Combine coffee and chilled drinking water in clean, food-safe equipment; wash hands before preparation.
- Steep 12–18 h in the refrigerator at 4 °C or below. This is a flavour starting window, not proof of microbial safety.
- Filter through mesh and paper into a clean container; measure the actual concentrate collected.
- Dilute the measured concentrate with an equal volume of water as a starting point. Add milk only to the portion being served.
Cold brew concentrate vs ready-to-drink ratios
Most home recipes make concentrate, which you dilute before drinking. The distinction matters because it affects how much coffee you actually need to buy.
Concentrate (1:4 to 1:8): Using 1 part coffee to 4–8 parts water gives a strong, syrupy brew. The 1:4 ratio produces a very intense concentrate — use it when you want a smaller-volume batch or plan to add a lot of milk. The 1:8 ratio (recommended here) is the most practical: strong enough to dilute 1:1 and taste like a full-flavored cup, but not so intense that it's unpleasant if you accidentally drink it less diluted.
Ready-to-drink (1:12 to 1:15): Brewing at this ratio means you can pour and drink straight from the fridge without diluting. It's convenient for batch brewing in a larger container (think 2-liter pitchers). The trade-off is that it takes up more fridge space and uses more water per gram of coffee.
Dilution guide for concentrate:
- 1:1 with water → standard cold brew over ice
- 1:1 with milk or oat milk → cold brew latte
- Add a splash of concentrate to sparkling water → cold brew fizz
- Straight over ice (no dilution) → very strong, use if you like that
The easiest way to scale your batch size is the ratio calculator.
Cold brew batch size chart
The ratio tells you how much coffee to use once you choose the amount of brewing water. For a concentrate, divide the water weight by 8. For ready-to-drink cold brew, divide it by 15. Water in milliliters is close enough to water in grams for a home recipe, so you can weigh the water or use the same number from a measuring jug.
| Batch size | Water | Coffee for 1:8 concentrate | Coffee for 1:15 ready-to-drink |
|---|---|---|---|
| One cup | 240 ml | 30 g | 16 g |
| Small batch | 500 ml | 63 g | 33 g |
| One liter | 1,000 ml | 125 g | 67 g |
| Large batch (vessel larger than 1.9 l) | 1.9 l | 238 g | 127 g |
Both columns describe input water, not filtered yield. Coffee grounds retain liquid; the amount depends on the coffee and filtration. Measure the concentrate after filtering before calculating dilution. For example, if you collect 180 ml, adding 180 ml water produces 360 ml before ice, not 480 ml.
A 64 US fl oz jar holds about 1.9 litres in total. It cannot hold 1.9 litres of water plus grounds and headspace. Choose a larger vessel or make a smaller batch; never fill a jar to the rim to match a chart.
Measuring without a scale
A scale is the easiest way to repeat a ratio, especially for batches larger than a single cup. If you only have spoons, use them as a rough starting point rather than a precise conversion: one level tablespoon of ground coffee is about 5–6 g. That means 30 g is roughly five to six tablespoons and 60 g is roughly ten to twelve. Bean density and grind size change the actual weight, so a tablespoon recipe can be useful once but hard to reproduce when you buy another coffee.
Do not measure coffee by liquid milliliters in a jug. Grounds trap air and settle differently from water. Measure water in milliliters and coffee in grams whenever possible. The coffee ratio calculator can scale a different mug or pitcher, even if you use a ready-to-drink ratio rather than the standard concentrate.
Dilution math: 1:1 and 2:1
Dilution is simply a second ratio after the brewing ratio. For 1:1, combine equal parts strained concentrate and water, milk, or a milk alternative. For example, pour 150 ml concentrate and 150 ml water over ice to make a 300 ml drink. This is the default for a 1:8 home concentrate.
For 2:1 water to concentrate, combine two parts water with one part concentrate. For a 300 ml drink, use 100 ml concentrate and 200 ml water. The result tastes lighter; diluting a fixed amount of concentrate does not remove its caffeine. This can suit a dark roast, a lighter drink, or a coffee that tasted too intense at 1:1. If you make a latte-style drink, start with 1 part concentrate to 1 part milk, then add ice. Milk changes perceived strength, so adjust by taste rather than trying to make its numbers match water exactly.
| Final drink | 1:1 dilution | 2:1 dilution |
|---|---|---|
| 240 ml glass | 120 ml concentrate + 120 ml water | 80 ml concentrate + 160 ml water |
| 350 ml tumbler | 175 ml concentrate + 175 ml water | 117 ml concentrate + 233 ml water |
| 500 ml bottle | 250 ml concentrate + 250 ml water | 167 ml concentrate + 333 ml water |
Ice melts, so a drink poured over a full glass of ice can taste lighter after a few minutes. If you like a slower, less diluted drink, use large cubes or chill the water before mixing. If the concentrate tastes too strong before any dilution, do not assume the coffee is bad: try 2:1 first. If it still tastes harsh, adjust the next batch by grinding coarser or reducing the steep time.
Choose the ratio for your routine
Use 1:8 concentrate when you want flexibility. It is practical for people who alternate between black cold brew, milk drinks, and a small strong pour before work. It also takes less fridge space after brewing because dilution happens in the glass. Use 1:12 to 1:15 ready-to-drink when you want to pour from a pitcher without thinking about a second step. It is simpler for a household or for serving several people, though it occupies more volume in the refrigerator.
Going stronger than 1:8, such as 1:4, is possible but needs a reason. It produces a small, intense concentrate that usually needs more dilution. It does not automatically make a better-tasting cup, and it can make filtering slower because there are more grounds for the same volume of water. Start at 1:8, then change only after you have tasted the batch at a known dilution.
Troubleshooting the ratio before changing coffee
Too weak after dilution: First check the dilution, not only the steep. A 1:8 concentrate that tastes fine straight can become watery when mixed 2:1. Try it at 1:1 before changing the next batch. If it is weak even undiluted, steep for 14–16 hours and make sure the coffee was not ground so coarsely that water barely contacted it.
Too bitter or dry: Fine particles and an overlong steep are common causes. Move one grind setting coarser, filter through paper, and keep the next refrigerated batch near 12–16 hours. A darker roast can also taste more intense at the same ratio; try 2:1 dilution before changing the recipe.
Cloudy or gritty: The ratio is usually not the issue. Let the grounds settle for a moment, strain through a mesh sieve, then use a paper filter. Pressing a French press plunger too quickly sends fines through the mesh. A slower press and a second paper filter give a cleaner cold brew without needing to buy new equipment.
Storage and room-temperature brewing
There is no verified two-week shelf-life promise for this home recipe. Refrigeration slows some microbial activity but does not sterilize a contaminated batch. UGA’s cold-brew research found that introduced pathogens could survive; normal taste or smell cannot prove safety.
Wash hands and equipment, use drinking water, keep the brew covered and refrigerated at 4 °C or below, label its date, and make small batches you plan to use promptly. Do not top up an old batch with new coffee. Discard a batch with mold, unusual changes or uncertain handling; do not taste it to determine safety. For packaged cold brew, follow its label after opening.
Keep black concentrate separate from milk and other additions. Add them to the serving and follow the ingredient’s own handling instructions. Dilution does not reset the storage clock or sanitize the drink.
Room temperature: this guide uses refrigerated brewing throughout. We do not endorse an 8–12-hour counter brew as safe or supply an unsupported ambient-time cutoff. The 12–18-hour window is a refrigerated flavour recipe, not a storage-life study.
Common questions
Cold brew vs iced coffee? Cold brew steeps cold hours; iced coffee is hot-brewed then chilled. Different flavor. Read cold brew vs iced coffee.
Why is my cold brew weak? Steep time too short, grind too coarse, or over-diluted.
Caffeine in cold brew? Concentrate is strong before dilution — adjust dose if sensitive.
How much cold brew concentrate should I dilute? Start with equal parts concentrate and water or milk. Taste that first, then use two parts concentrate to one part liquid for a stronger cup.
Can I make cold brew without a scale? Yes, but use the same coffee scoop and measuring jug for every batch. A scale is the simpler way to repeat the ratio when you want to troubleshoot taste.
Calculate batch size in the ratio calculator.
Sources, adaptation and limits
University of Georgia, “Can cold brew coffee make you sick?” (opens in a new tab), survival-study findings and home-preparation advice, supports contamination control and refrigeration. It does not validate a universal home shelf life. FDA, “Are You Storing Food Safely?” (opens in a new tab), refrigerator temperature and food-safety guidance, supports 4 °C or below and the limits of sensory checks.
The 1:8 ratio, grind and 12–18-hour tasting window are CoffeeMethods editorial starting points, not safety tests or measured extraction results. Batch and dilution examples are arithmetic; finished yield must be measured. Use the cold brew calculator for both steps.