Cold brew concentrate, step by step

Cold brew is the least technical coffee you can make and the easiest to make badly. The difference between syrupy-sludge and clean concentrate is three decisions: the ratio, the grind and the time. The Toddy system — the original commercial cold brew kit, whose instruction sheet has anchored this method for decades — publishes all three, and they convert cleanly to grams.

The numbers up front

Source, fetched 2026-11-16 (nofollow): Toddy retail instruction sheet (PDF).

The recipe (full Toddy batch, 1.65 L water)

1. Coarse-grind 340 g of coffee — as coarse as your grinder goes. Fine grinds over-extract the muddy flavors and clog the filter; this is the one step Toddy is strictest about.
2. Add 1 cup of water to the container first, then the grounds, then pour the remaining water in slow circles, gently saturating everything. Toddy warns against vigorous stirring — it clogs the filter pad.
3. Steep 12 hours at room temperature. Longer is not better; past 12–14 hours woody, bitter notes accumulate.
4. Drain (or strain through a paper filter if you're using a mason jar), and you have about 1.2–1.3 L of concentrate.
5. Serve at 1:2 to 1:3. One part concentrate over ice with two parts water or milk is the classic serve; taste and adjust — concentrate is forgiving in exactly one direction.

Scaling to a jar

You don't need the 1.65 L system. Keep the 1:5 ratio and shrink it: a 1-litre mason jar holds about 800 g of water comfortably, needing 160 g of coffee; a 500 g water batch needs 100 g. Our ratio calculator has a cold-brew preset that does the division, including a lighter 1:8 "ready-to-drink-ish" option for concentrate you'll drink mostly black. The only non-proportional rule is time: 12 hours stays 12 hours whether you brew 300 g or 3 kg — extraction time scales with particle size and temperature, not batch size.

Why cold brew's ratio looks so different

Water at room temperature is a feeble solvent; it takes those 12 hours to do what 96°C water does in four minutes, and it extracts far less acid on the way — which is the famous smoothness. Because the result is a concentrate meant to be cut with water or milk, the brew ratio (1:5) and the serving ratio (1:2 to 1:3) stack: your actual drinking strength ends up around 1:15–1:20, right back in filter-coffee territory. This stacking is also the most common cold-brew accounting mistake — people compare the 1:5 brew number to a pour-over's 1:15 and conclude cold brew is triple strength. It isn't; it's just waiting to be diluted (a point we revisit in common ratio mistakes).

Hot-brew vs cold-brew ratios are not interchangeable

If you take a 1:15 hot recipe, add cold water and refrigerate it overnight, you get cold drip-strength coffee with hot-extraction chemistry — more acidity, different sweetness, often thinner body. It's a legitimate style (Japanese iced method is its hot-poured cousin), but it is not Toddy-style concentrate, and the recipes don't transfer. Match the method to the recipe, and see our grind chart row for cold brew before you grind — extra coarse is doing real work here.

Troubleshooting, one variable at a time

• Too strong to drink black: dilute more at serving — that's the design, not a flaw.
• Muddy or woody: grind coarser and pull the steep back to 12 hours.
• Weak even at 1:4: check the grind first (too coarse to the point of boulders extracts almost nothing), then extend to 14 hours before tightening the ratio.
• Sour, almost salty: that's under-extraction — finer grind, not more coffee.

Related reading

• Ratios by method — the full table including cold brew
• Water quality basics — cold amplifies bad water's flatness
• Grind size vs extraction — why time replaces heat
• French press guide — the other set-and-wait method