Coffee Calculators
Cold Brew Coffee Calculator: Concentrate and Ratios
Cold brew is the one method where the ratio does most of the work, because there is no temperature or pour technique to hide behind. The cold brew coffee calculator above takes your jar size and returns the grams of coarse ground coffee to use, for either a concentrate or a ready to drink batch. Pick which one you want first, since the two ratios are very different.
The rest of this page explains what those numbers mean in practice: grind, steep window, straining and how much water to add back at the end.
Short answer: for concentrate, use 1 gram of coffee for every 5 grams of water, so about 200 g of coffee per liter. Steep 12 to 18 hours, strain, then dilute roughly one to one in the glass. For ready to drink cold brew, use about 1:8, or 125 g per liter, and skip the dilution.
What the cold brew coffee calculator is solving
Cold water extracts slowly and gently. It never gets the chance to pull the harsh compounds that hot water can, which is why cold brew tastes smooth and low in acidity. The trade is that it needs far more coffee and far more time to reach a normal strength.
That is the whole reason the ratios look extreme next to drip coffee. A drip pot at 1:16 is finished in five minutes. A cold brew at 1:5 needs most of a day, and even then the result is a concentrate rather than a drink.
The calculator handles both modes. Concentrate mode uses 1:4 to 1:5 and expects you to dilute later. Ready to drink mode uses about 1:8 and gives you a jar you can pour straight over ice.
Concentrate doses by jar size
These use 1:5, the friendlier end of the concentrate range:
- 500 ml water: about 100 g of coffee
- 950 ml water (a 1 quart mason jar): about 190 g of coffee
- 1,000 ml water: about 200 g of coffee
- 1,900 ml water (a half gallon jar): about 380 g of coffee
At the stronger 1:4 end, that 1 liter batch climbs to 250 g. Expect to get back less liquid than water you poured in, because wet grounds hold on to roughly twice their own weight in water. A liter of water at 1:5 yields somewhere near 600 ml of concentrate once strained.
For ready to drink batches at 1:8, the same jars need about 62 g, 119 g, 125 g and 238 g respectively. That version tastes lighter and does not keep as long.
Grind, steep time and straining
Grind coarse, similar to what a french press wants. Fine grounds turn the strain into a slow, cloudy mess and can push the batch bitter over a long soak. Medium coarse is the sweet spot if your cup comes out weak at full coarse.
Steep 12 to 18 hours. Counter temperature works faster than the fridge, so 12 to 14 hours on the counter and 16 to 18 in the fridge are reasonable defaults. Longer is not stronger past that point, it is just woodier.
Strain twice. Pull the bulk of the grounds out through a mesh sieve first, then pass the liquid through a paper filter or a clean cloth. Skipping the second pass leaves fines that keep extracting in the fridge and make day three taste like day one gone wrong.
Diluting and serving
Start at one part concentrate to one part water or milk, then adjust. Ice melts into the glass and dilutes further, so pour over ice a touch stronger than you want it. If you like it closer to drip strength, one part concentrate to one and a half parts water is a common landing place.
Concentrate is worth the extra step because it keeps longer and lets you change strength per glass. A sealed jar in the fridge holds up for about a week to ten days.
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A cold brew jar with a built in filter basket removes the messiest part of the process, which is the reason most people quit the method after two batches. The BrewChart Card carries the cold brew ratios, steep window and grind size on one printable sheet with every other brew method.
Fixing a cold brew batch that missed
Weak and watery is the common complaint, and it is almost never the ratio. Check the grind first, then the steep length. Only after both are right should you move from 1:5 to 1:4.
Bitter or woody cold brew means the opposite: too fine a grind, too long a steep, or grounds left in the jar after straining. Cut the steep back to 12 hours and coarsen up. That same over-extraction logic is spelled out in over and under extracted coffee.
Flat, cardboard flavor is usually stale beans rather than technique. Cold brew is often where people use up old coffee, and a long steep exaggerates the staleness instead of hiding it.
The verdict on the cold brew coffee calculator
Cold brew rewards patience and punishes shortcuts. Use the cold brew coffee calculator above to lock the dose, grind coarse, steep the full window, and strain properly. Those four steps decide the batch before dilution ever enters the picture.
The french press calculator runs the same soaking idea at hot temperatures. If you switch brewers with the seasons, the coffee to water ratio calculator covers every other method.
Quick answers
What is the ratio for cold brew concentrate?
Between 1:4 and 1:5 by weight, with 1:5 as the easier default. One liter of water at 1:5 takes about 200 g of coarse ground coffee. You then cut the finished concentrate with roughly equal parts water or milk in the glass.
How long should cold brew steep?
Between 12 and 18 hours. Twelve hours on the counter and closer to 18 in the fridge, since cold water works more slowly. Past about 20 hours most batches turn woody and bitter rather than stronger, so set a reminder instead of leaving it overnight twice.
Can I make cold brew ready to drink instead of concentrate?
Yes. Use roughly 1:8 instead of 1:5, so about 125 g of coffee per liter of water, and drink it straight from the jar. Concentrate is more flexible because you can dilute to taste, but ready to drink saves a step every morning.
Why is my cold brew weak and watery?
Usually the grind is too coarse or the steep was cut short. Cold water pulls flavor slowly, so both matter more than in hot brewing. Move to a medium coarse grind and push the steep to the full 18 hours before you touch the ratio.
Does cold brew need a special maker?
No. A large jar and a fine mesh strainer lined with a coffee filter work fine. A dedicated maker with a built in filter basket mostly saves mess at the straining step, which is the part people abandon the method over. Either way, strain twice for a clean jar.
How long does cold brew keep?
Concentrate holds up in a sealed jar in the fridge for about a week to ten days. Diluted cold brew fades faster, in two or three days, because it is mostly water. Make concentrate and cut it a glass at a time rather than diluting the whole batch.