One ratio is not enough
Most cold brew instructions fail for the same reason: they give a single ratio without saying whether the result is meant to be drunk straight or diluted. Those are two different drinks. A 1:8 brew drunk neat is thin. A 1:5 brew drunk neat is syrup.
Pick the ratio by how you plan to serve it, then stay consistent so you can adjust one variable at a time.
The chart
| Style | Coffee : water | For 60 g coffee | Serve | Steep |
|---|---|---|---|---|
| Concentrate | 1 : 5 | 300 g water | Dilute 1:2 or 1:3 | 16–18 h |
| Strong ready-to-drink | 1 : 8 | 480 g water | Neat over ice | 14–16 h |
| Standard ready-to-drink | 1 : 10 | 600 g water | Neat over ice | 12–14 h |
| Light and easy | 1 : 12 | 720 g water | Neat, or with a splash of milk | 12 h |
Weigh the water, do not measure it in cups. A cup of water is 236 g on paper and something else in your actual cup, and cold brew has no heat to hide the error.
Grind: coarse, and more coarse than you think
Cold brew wants a grind like coarse sea salt, noticeably coarser than pour-over. Fine particles pass through the filter and keep extracting in the bottle, which is how a batch turns bitter on day three. If your grinder produces a lot of dust at the coarse setting, grind slightly coarser and add a couple of hours of steep time to compensate.
A hand grinder with a wide adjustment range handles this well. Our Manual Coffee Grinder Pro covers the coarse end cleanly, and our guide to grind sizes maps the settings across brew methods if you want a reference point.
Steep time and temperature
Twelve to eighteen hours is the working range. Longer is not automatically better: past twenty hours you extract more of the papery, woody compounds and less of the sweetness. Room temperature brews faster than fridge brewing, so if you steep on the counter, aim for the lower end of the range.
Fridge steeping is the safer default. It is slower, more forgiving, and you cannot forget about it as easily, because it is already where you will store the result.
Batch size: work backwards from your bottle
The most common cold brew mistake is brewing more than you will drink before it starts to fade. Cold brew holds five to seven days in the fridge, so a batch should be a week of drinking, not a month.
- A 430 ml bottle takes about 40 g of coffee at a 1:10 ratio and makes two generous glasses.
- The 560 ml version takes about 52 g and makes three.
- If you drink one glass a day, brew twice a week rather than once.
Scale the numbers to your own bottle: grams of coffee equals millilitres of water divided by the ratio. For a 500 ml bottle at 1:10, that is 50 g.
Dilution math for concentrate
A 1:5 concentrate needs water added at serving time. For a 250 ml glass, use roughly 80 ml of concentrate topped with 170 ml water or milk for a standard strength, or 100 ml concentrate for a stronger pour. Write the dilution you liked on the bottle so the next glass is not a guess.
Freeze leftover concentrate in an ice tray. Those cubes chill iced coffee without diluting it, which is the one place where a strong batch is genuinely better than a ready-to-drink one.
Water matters more than most guides admit
Cold brew is roughly 98 percent water, and you taste it directly because nothing is hot enough to mask it. Use filtered water at fridge temperature. Tap water that tastes fine from the glass will taste metallic after sixteen hours of contact with coffee, and hard water mutes the fruit notes you were trying to preserve.
Do not use distilled water either. It has no minerals, and the extraction goes flat and papery. Filtered tap is the right answer for almost everyone.
One more timing note: cold brew holds five to seven days in the fridge, so a batch should be sized to what you will finish, not to what the jug holds. Our guide to cold brew shelf life covers the storage side in detail.
Adjusting for taste
| What you taste | Likely cause | Change one thing |
|---|---|---|
| Thin and watery | Ratio too weak or steep too short | Add 5 g of coffee per 500 ml |
| Harsh and bitter | Grind too fine, or over 20 h | Grind coarser, steep 2 h less |
| Flat and papery | Beans past their prime | Use beans roasted within the last month |
| Muddy, lots of sediment | Fine particles through the filter | Second pass through a paper filter |
Frequently asked questions
Can I use a pour-over ratio for cold brew?
No. Pour-over at 1:16 relies on hot water for extraction speed. The same ratio in cold water over sixteen hours tastes weak and hollow.
Do I need a scale for cold brew?
You need one more than you do for pour-over, because you have no feedback while brewing. A 0.1 g scale removes the guesswork from both the coffee and the water.
Does cold brew use more coffee than pour-over?
Yes, by weight, roughly two to three times per finished litre. That is the trade for a smoother cup and a batch that lasts a week.
Start with one bottle and one ratio
Brew a single 1:10 batch, drink it over four days, and change one variable next time. Two or three batches in, you will have a house recipe that no chart can give you. Our cold brew bottles are built for exactly that loop: brew, cap, refrigerate, repeat.
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