Cold brew is not iced coffee. Iced coffee is brewed hot and then chilled, which keeps the acidity and aroma of a hot brew. Cold brew never sees heat at all - the coffee simply sits in cold water for the best part of a day.
That difference changes what comes out. Many of the compounds responsible for perceived acidity and bitterness are far less soluble in cold water, so they mostly stay in the grounds. What you get instead is a sweet, smooth, heavy-bodied coffee that tastes of chocolate, caramel and dark fruit almost regardless of which coffee you started with.
Concentrate or ready to drink?
Decide this before you start, because it sets your ratio.
| Style | Coffee | Water | How to serve |
|---|---|---|---|
| Concentrate | 100 g | 1 L | Dilute 1:1 with water, milk or tonic |
| Ready to drink | 65 g | 1 L | Straight over ice, no dilution |
| Strong concentrate | 125 g | 1 L | Dilute 1:2, best for milk drinks |
We brew concentrate at the roastery. It takes up less fridge space, keeps better, and lets you decide the strength of each glass - dilute with water for a long iced coffee, with milk for something closer to an iced latte, or with tonic and a slice of orange for the drink half of Lisbon spends the summer on.
Time, temperature and grind
How long
16-18 hours in the fridge is our window. Under 12 and the brew is thin and sour; past 24 the coffee turns woody, dull and slightly astringent. Cold brew does over-extract - it just takes a day to do it.
At room temperature everything runs faster and 12-14 hours is enough. It also extracts a little more, which gives a fuller but slightly less clean cup. Both work; the fridge is more forgiving.
Grind
Coarse, exactly like a French press. Cold water extracts slowly, so it is tempting to grind finer to compensate. Do not - a fine grind over 16 hours gives you a bitter, muddy brew that is almost impossible to strain clean.
Water
Cold and filtered. Since there is no heat to hide behind, water quality shows up more here than anywhere else.
Straining properly
This is the step most home recipes skip, and it is the one that decides whether your cold brew looks like a café's or like muddy water.
Strain twice. First pour off the grounds through a fine mesh sieve or a French press to get the bulk out. Then pass the liquid through a paper filter - a V60 or Chemex® cone works perfectly, though a litre takes a few minutes to pass through.
Do not press or squeeze the grounds to get the last of the liquid out. That is the most bitter, most over-extracted coffee in the jar, and it will drag the whole batch down with it.
Storing and serving
Sealed in a clean bottle in the fridge, cold brew concentrate keeps for about 10 days without any real loss of quality. Diluted cold brew has a shorter life - about 3 days - so dilute per glass rather than by the jug.
- Classic iced - concentrate and cold water 1:1 over plenty of ice
- Iced white - concentrate and cold milk 1:1, poured over ice
- Espresso tonic style - 50 ml concentrate, tonic water, a slice of orange
- Cold brew ice cubes - freeze some concentrate so your drink never waters down
Serve it colder than you think. Cold brew tastes noticeably sweeter and rounder at fridge temperature than it does at room temperature.
Troubleshooting
| Problem | Likely cause | Fix |
|---|---|---|
| Weak and watery | Ratio too lean, or under-steeped | Use more coffee, steep the full 16 h |
| Bitter and woody | Steeped over 24 h, or grind too fine | Cut to 16-18 h; grind coarser |
| Cloudy and silty | Only strained through mesh | Finish through a paper filter |
| Sour and thin | Grounds not fully wet at the start | Stir thoroughly after adding the water |
| Tastes flat and dull | Stale coffee, or brewed over a week ago | Use fresh coffee; drink within 10 days |
Which coffee to use
Cold brew flattens acidity, which means a delicate, expensive washed Ethiopian will lose most of what makes it special. Save those for a V60.
Instead reach for coffees with sweetness and body - naturals, honeys, Brazilians, anything with chocolate, caramel or dried fruit in the notes. Our Espresso Blend makes excellent cold brew and does it cheaply, which matters when a batch uses 100 g at a time.
Decaf is also worth a mention here: cold brew is strong and very drinkable, which makes it easy to have three glasses on a hot afternoon without meaning to.
Cold brew questions, answered
What is the cold brew coffee-to-water ratio?
1:10 for a concentrate you dilute before drinking - 100 g of coffee to 1 litre of water. For cold brew you can pour straight over ice, use 1:15, around 65 g to a litre.
How long should cold brew steep?
16-18 hours in the fridge, or 12-14 hours at room temperature. Under 12 hours it tastes thin and sour; past 24 hours it turns woody and astringent.
What grind size for cold brew?
Coarse, the same as a French press. It is tempting to grind finer because cold water extracts slowly, but a fine grind over 16 hours gives a bitter, muddy brew that will not strain clean.
Is cold brew the same as iced coffee?
No. Iced coffee is brewed hot and then chilled, so it keeps the acidity and aroma of a hot brew. Cold brew never touches heat, which leaves most of the acidic and bitter compounds behind in the grounds.
How long does cold brew last in the fridge?
Concentrate keeps about 10 days sealed. Once diluted it is best within about 3 days, so dilute each glass rather than the whole jug.
Is cold brew stronger than normal coffee?
As a concentrate, yes - considerably. Once diluted 1:1 it is comparable to a strong filter coffee. The lower acidity makes it taste smoother, which can disguise how much caffeine is actually in the glass.
Can I make cold brew at room temperature?
Yes. It takes 12-14 hours instead of 16-18 and extracts a little more, giving a fuller but slightly less clean cup. Refrigerate it as soon as it is strained.
Keep going
Cold brew uses the same coarse grind as the French press, so if you own one you already have everything you need except patience.
For something cold and bright rather than cold and sweet, brew a V60 directly onto ice - hot water, half the usual water weight, the other half as ice in the server. It keeps the aroma cold brew leaves behind.
