# How to Make Cold Brew Concentrate

> A 1:5 cold brew concentrate recipe by weight, with steep times, grind size, a dilution table and the mistakes that make it bitter.

Topic: Cold Brew & Iced  
Published: 2026-08-29T09:00:00-04:00  
Updated: 2026-08-29T09:00:00-04:00  
Author: Mical Robert, Editor (https://trysix.online/author/mical-robert)  
Canonical: https://trysix.online/how-to-make-cold-brew-concentrate

## The short answer

Steep coarse grounds in cold water at 1:5 by weight — 200 g to 1 litre — for 16 to 24 hours, then filter. The result is about three times drip strength, so dilute it 1:1 or 1:2. It keeps two weeks.

## Key takeaways

- 1:5 by weight is the concentrate ratio. 1:8 gives you ready-to-drink cold brew that needs no dilution.
- Grind coarse — the texture of raw sugar. Fine grounds pass through the filter and turn the batch muddy and bitter.
- 16 hours at room temperature extracts about as much as 24 hours in the fridge. Past 24 hours you gain very little.
- Dilute 1:1 with water for a strong cup, 1:2 for something closer to drip strength, 1:1 with milk for an iced latte.

Making cold brew at full strength means brewing a new batch every couple of days and giving up a shelf of your fridge to it. Concentrate solves both problems: one jar lasts two weeks, takes up a fraction of the space, and turns into iced coffee, a hot mug or a milky drink in about ten seconds.

## What concentrate actually means

Cold brew concentrate is not a different drink from cold brew. It is cold brew made with far less water, so it has to be watered down before you drink it. That is the whole distinction, and it matters because most disappointment with homemade cold brew comes from making concentrate by accident and then drinking it neat.

Drip coffee is brewed at roughly 1:16 — one gram of coffee for every 16 grams of water. Concentrate runs at 1:5, so about three times as much coffee sits in the same volume of water. That is why a 1:2 dilution lands you back near normal drinking strength.

> **The one number to remember** — 1:5 by weight. 200 g of coffee, 1,000 g (1 litre) of water. Everything else in this recipe is a preference; that ratio is the recipe.

## What you need

- 200 g whole coffee beans, ground coarse — a medium roast is the most forgiving starting point
- 1 litre of cold filtered water (tap water is fine if yours tastes fine)
- A 1.5–2 litre jar or pitcher with a lid
- A fine mesh sieve and either a paper filter, a cloth, or a nut-milk bag for the final strain
- A kitchen scale — this recipe is by weight, and volume measures are where it goes wrong

If you have no grinder, ask for a coarse or French press grind wherever you buy the beans. Standard supermarket pre-ground coffee is cut for drip machines and is too fine; it will still work, but shorten the steep to about 12 hours and expect more sediment. Our guide to [grinding coffee beans](https://trysix.online/how-to-grind-coffee-beans) covers the grind sizes in more detail.

### The method

1. **Weigh and grind** — Weigh 200 g of beans and grind them coarse. Coarse means visibly chunky, like raw sugar or coarse sea salt — not powder. Grind size controls how much surface area the water reaches, and over 16 hours a fine grind will over-extract badly.
2. **Combine** — Tip the grounds into the jar, pour on 1 litre of cold water, and stir until no dry pockets remain. Dry clumps float and never extract, which quietly weakens the batch.
3. **Steep** — Lid on. Leave 16 hours at room temperature, or 24 hours in the fridge. Room temperature extracts faster because extraction rate rises with temperature; the fridge is slower but slightly cleaner tasting.
4. **Strain twice** — Pour through a mesh sieve first to catch the bulk of the grounds, then through a paper filter or cloth to catch the fines. Do not press or squeeze the bed — squeezing forces bitter, over-extracted liquid through.
5. **Bottle and date it** — Pour into a sealed bottle and write the date on it. Undiluted concentrate keeps around two weeks in the fridge; once diluted, drink it within about three days.

## How long to steep

Steep time and temperature trade off against each other. A 2017 study in Scientific Reports measured caffeine and chlorogenic acid in cold brew across different times, temperatures and grind sizes and found that extraction rises steeply early on and then flattens — the curve is not linear, and the last few hours contribute far less than the first few.

**Figure: Steep time versus extracted strength**

| Item | Value |
| --- | --- |
| 6 hours (Thin, sour, clearly under-extracted) | 55% |
| 12 hours (Drinkable; slightly light-bodied) | 85% |
| 16 hours (The sweet spot for room temperature) | 95% |
| 24 hours (Full extraction; fridge equivalent) | 100% |
| 36 hours (No real gain; woody flavours appear) | 101% |

_Approximate share of achievable extraction by steep time at room temperature, coarse grind. Most of the work happens in the first 12 hours._

The practical reading: steeping longer than 24 hours is not a way to make cold brew stronger. If you want it stronger, use more coffee. Extending the steep mostly adds the papery, woody notes that come from the grounds themselves.

## The dilution table

**Diluting 1:5 concentrate. Ratios are concentrate to liquid, by volume.**

| You want | Concentrate | Add | Rough strength |
| --- | --- | --- | --- |
| A strong iced coffee | 1 part | 1 part water | About 1.5× drip |
| Standard iced coffee | 1 part | 2 parts water | About drip strength |
| Iced latte | 1 part | 1 part milk | Strong, milky |
| Hot cold brew | 1 part | 2 parts hot water | About drip strength |
| An affogato-style pour | 1 part | nothing | Very strong; use 30–60 ml |

Ice counts as dilution. A glass filled with ice adds roughly 30–60 ml of water as it melts, so if you are pouring over a full glass of ice, start one step stronger than the table suggests.

## What goes wrong

**Diagnosing a bad batch of concentrate.**

| Problem | Most likely cause | Fix |
| --- | --- | --- |
| Bitter, harsh, drying | Grind too fine, or squeezed the filter bed | Coarsen the grind; let it drain unaided |
| Sour and thin | Steeped under 12 hours, or ratio too weak | Steep 16 h; check you weighed 200 g |
| Muddy, silty texture | Only strained once | Second strain through paper or cloth |
| Weak even undiluted | Measured by volume, not weight | Weigh it — scoops vary with grind and roast |
| Tastes woody or papery | Steeped beyond 24–36 hours | Cut the steep back to 16–24 h |

> **Where the evidence is thin** — Precise steep-time curves depend on grind, roast and water chemistry, and published measurements vary between studies. Treat the percentages above as a shape, not a specification — the reliable finding is that returns flatten, not that 16 hours is exactly 95 percent.

## Concentrate versus ready-to-drink

If you only ever drink it one way, skip the concentrate and [brew at 1:8 instead](https://trysix.online/how-to-make-cold-brew-coffee). That produces cold brew you can pour straight over ice with no dilution step. Concentrate is worth the extra coffee when you want fridge space back, when you want to make hot and iced drinks from the same batch, or when you want it to keep longer.

Concentrate also behaves better in milk. Because it is already three times as strong, it survives being cut with milk without tasting like coffee-flavoured milk — which is exactly what a 1:8 batch does in a latte.

> Cold brewing produced coffee with measurably lower titratable acidity than hot brewing at equivalent roast levels.
>
> — Rao & Fuller, Scientific Reports (2018)

That lower acidity is the reason cold brew reads as smooth and slightly sweet even at high strength. It is also why some people find it easier on the stomach, though as our piece on [whether cold brew is healthy](https://trysix.online/is-cold-brew-coffee-healthy) explains, the evidence for that specific claim is much weaker than the marketing implies. If you want the caffeine question answered properly, see [whether cold brew is stronger](https://trysix.online/is-cold-brew-stronger).

## Frequently asked questions

### What is the ratio for cold brew concentrate?

1 part coffee to 5 parts water by weight — 200 g of coffee to 1 litre of water. Ready-to-drink cold brew, which needs no dilution, is brewed at about 1:8.

### How long does cold brew concentrate last in the fridge?

Undiluted and sealed, roughly two weeks. Once you dilute it with water or milk it starts tasting flat within about three days, so dilute per glass rather than by the bottle.

### Can I make cold brew concentrate with pre-ground coffee?

Yes, but supermarket pre-ground is cut for drip machines and is finer than ideal. Shorten the steep to about 12 hours, strain twice, and expect more sediment in the bottom of the bottle.

### Do I need to use cold water?

Room-temperature water is fine and extracts a little faster. What matters is that you never use hot water — heat pulls a different set of acids and aromatic compounds, which is precisely the [difference between cold brew and iced coffee](https://trysix.online/cold-brew-vs-iced-coffee).

## Sources

- [The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee](https://doi.org/10.1038/s41598-017-18247-4) — Scientific Reports (2017) (DOI 10.1038/s41598-017-18247-4). Supports the finding that cold brew extraction rises steeply early and flattens after roughly 12–24 hours.
- [Acidity and Antioxidant Activity of Cold Brew Coffee](https://doi.org/10.1038/s41598-018-34392-w) — Scientific Reports (2018) (DOI 10.1038/s41598-018-34392-w). Supports the measured claim that cold brew has lower titratable acidity than hot-brewed coffee at matched roast levels.
- [How to Brew Coffee](https://www.ncausa.org/About-Coffee/How-to-Brew-Coffee) — National Coffee Association USA. Supports the general brewing ratio and water-quality guidance used as the baseline comparison to drip coffee.

## Related articles

- https://trysix.online/how-to-make-cold-brew-coffee
- https://trysix.online/is-cold-brew-stronger
- https://trysix.online/cold-brew-vs-iced-coffee
- https://trysix.online/how-to-grind-coffee-beans

---
Brewnote · https://trysix.online · contact@trysix.online