TL;DR: Start at 1:8. Wait sixteen hours. Dilute one-to-one, and adjust from there. OR, use this tool here:
Cold brew ratio calculator
Tell it what you want. It will tell you what to weigh.
What are you making?125g coffee · 1,000g water
Ratio 1:8
Ratios after the Toddy cold brew protocol
Cold brew swaps heat for time.
Everything else about it is decided before the waiting begins, and the biggest decision is the ratio: how much coffee meets how much water in the jar. Get that number right and the fridge does the rest. Get it wrong, and eighteen hours later, you will be drinking brown water with a muddy texture.
Here is how the numbers work, where the professionals set them, and how to land the glass you actually wanted to make cold brew coffee.
First, decide what you are making: cold brew concentrate or ready-to-drink
Cold brew comes in two honest forms, and most people confuse them.
Concentrate is brewed strong on purpose, too strong to drink neat, and diluted with water, milk, or ice at serving time. It stores compactly and lets everyone at the table choose their own strength.
Ready-to-drink is brewed at drinking strength. You pour it straight from the fridge, no maths at the glass, and you can drink it straight.
Neither is more correct. But every ratio question that follows depends on which one you have chosen, so choose first.
The cold brew coffee ratios that work
Toddy, the company that has been making cold brew equipment since 1964, maps the spectrum neatly in its cold brew protocol, and the industry broadly agrees:
| What you are making | Ratio | In practice | Serve |
|---|---|---|---|
| Strong concentrate | 1:4–1:5 | 80 g coffee : 400 g water | Dilute — start at 1 part concentrate : 1–2 parts water or milk |
| Balanced concentrate | 1:7–1:8 | 125 g coffee : 1 litre water | Dilute ~1:1 |
| Strong ready-to-drink | 1:10 | 50 g : 500 g | Pour straight |
| Everyday ready-to-drink | 1:12–1:15 | 36 g : 500 g | Pour straight |
For reference points from the wider industry:
Stumptown's home recipe is a full 340 g bag of coffee to half a gallon of water (roughly 1:5.5), diluted one-to-one before drinking.
Counter Culture prefers 1:8 (about 125 g per litre), diluting 1:1 at the end, and notes you can push down to 1:4.5 if you like it fierce, or brew at around 1:11 and skip dilution entirely.
A simple way to choose, if you know what you already drink:
| If you usually drink… | Start with |
|---|---|
| Black filter coffee | 1:14–1:15 |
| Coffee over lots of ice | 1:12–1:13 |
| Iced coffee with milk | 1:8 concentrate, diluted with milk |
| Big batches for the week | 1:7–1:8 concentrate |
If you are starting from nothing: brew a 1:8 concentrate and dilute one-to-one. It is the sweet spot and the most forgiving door into cold brew there is.
How to cold brew, a step-by-step guide
Grind size should be coarse. French-press territory, like raw sugar. A long steep extracts patiently, so fine grounds tip into harshness and make filtering miserable. Some roasters, Counter Culture among them, go a touch finer (medium-coarse) to pull more sweetness. Pick one setting and let it be your constant.
Weigh everything. One millilitre of water weighs one gram of coffee, so the scale does both jobs. For a one-litre jar at 1:8, that is 125 g of coffee to 1,000 g of water.
Wet all the grounds. Pour, then stir gently. Dry pockets in the middle of the bed brew nothing.
Steep in the fridge, 14–16 hours to start. The workable window runs 12–24; shorter reads thin, and past 24 hours the returns turn muddy. Cold and covered is also the food-safe way to do it.
Strain. Paper gives the cleanest glass; a mesh or coffee filter leaves more body. Both are right; it is a texture decision, not a quality one.
What is in your jar now depends on the choice you made at the start. If it were a concentrate, one step remains.
The cold brew dilution ratios
Aim for a final glass somewhere near ordinary filter strength, around 1:13 to 1:16 once everything is counted.
The arithmetic is friendlier than it looks. Take your brew ratio's water number, and add the water you pour at serving time:
- 1:8 concentrate, diluted 1:1 → roughly 1:16 in the glass
- 1:5 concentrate, diluted with 2 parts water per part concentrate → roughly 1:15
- 1:7 concentrate, diluted 1:1 → roughly 1:14
One honest footnote: the grounds keep about a fifth of the brew water for themselves, so your concentrate runs slightly stronger than the naive maths suggests. Treat the numbers as a landing zone, then let your tongue make the final call. Ice counts as water too, if you are pouring over a tall glass of it, dilute a little less.
What cold brew tastes like, and what to brew it with
Cold water is a gentle solvent. It leaves much of the sharpness and bitterness behind and takes its time with the sugars, which is why the final drink reads round, sweet, and low in perceived acidity, chocolate, nuts, and stone fruit tend to step forward, and delicate notes survive without heat to burn them off.
Which means the coffee you choose is unusually audible. Something like our Guatemala San Andres Geisha makes a mellow, tea-like glass that wants no milk at all. Our Ethiopia Amederaro Konga runs brighter and juicier, and holds its own over ice.
When the glass disappoints
Thin or watery → steep longer next time, or tighten the ratio one step (1:8 → 1:7).
Harsh, woody, bitter → the grind is usually the culprit, not the ratio. Go coarser, or shorten the steep.
Muddy or gritty → a filtration problem. Strain again through paper.
The house rule from every other brew method holds here too: change one variable at a time, and let the ratio be the thing you trust while the rest settles.
Too impatient for eighteen hours?
So are we, most days. Our published cold answer is flash brew, hot extraction straight onto ice, done in three minutes, with the aromatics intact. The recipe lives in our brew ratio guide, and it remains the fastest route from a bag of good beans to good cold coffee.
Keep learning with us
If cold extraction has you curious about the rest of the craft, our coffee course at Prodigal Roasters runs on weekends, hands-on, scales provided, questions encouraged. And the two coffees above are on the shelf now, roasted with the same care either way you brew them.
FAQs
What is the best cold brew ratio?
For concentrate: 1:5 to 1:8, diluted before drinking, 1:8 with a 1:1 dilution is the friendliest starting point. For ready-to-drink: 1:12 to 1:15, poured straight.
How much coffee do I need for one litre of cold brew?
At 1:8, about 125 g of coarsely ground coffee to 1,000 g of water. At a strong 1:5, 200 g.
What is the best brew time for cold brew?
Start at 14–16 hours in the fridge. The workable range is 12–24; beyond that the flavour turns muddy rather than stronger.
Fridge or counter?
Fridge. It is the food-safe option, and it keeps batch after batch consistent.
Do I have to dilute cold brew?
Only if you brewed a concentrate (1:4–1:8). Brewed at 1:11 or wider, it is ready as it is.
Does cold brew have more caffeine?
Per millilitre, a concentrate carries considerably more than drip coffee. Diluted to drinking strength, it lands in familiar territory; the smoothness just makes it easier to drink quickly, which is its own kind of warning.
Can I use hot coffee to make cold brew?
No. Cold brew is made by steeping coffee grounds in cold water for 12–24 hours. If you brew coffee with hot water and chill it afterwards, you've made iced coffee or flash brew instead. While both are served cold, hot brewing extracts different flavours, resulting in a brighter and more aromatic perfect cup than cold brew.
What brewing equipment do I need to make cold brew?
You only need a few basic items: a bottle, mason jar or brewing vessel for steeping, a kitchen scale to measure your coffee and water, coarse-ground coffee, and a filter to strain the grounds. A paper filter produces the cleanest cup, while a fine mesh sieve or cloth filter leaves more body. Dedicated cold brewer makers are convenient but not necessary.
Do I need to use filtered water and/or cold water for my cold brew?
Filtered water is recommended because it improves the overall flavour and can make the best coffee. Cold or room-temperature water, or even ice cubes, can be used for brewing, but it's best to refrigerate your cold brew. This keeps the extraction consistent and is the safest method for long brew times.