What ratio should I use for cold brew concentrate?

Use 1:5 by weight — 200g of coarsely ground coffee to 1 liter of filtered water — then dilute the finished concentrate 1:1 with water or milk when serving. For a ready-to-drink batch that needs no dilution, brew at 1:8 (about 125g coffee per liter).

Do I really need a burr grinder for cold brew?

Yes, if you want smooth, low-sediment coffee. Blade grinders and pre-ground coffee create uneven particles that over-extract into bitterness while leaving muddy grit. A manual burr grinder for $40-70 produces the even, coarse grind cold brew needs.

How long does homemade cold brew concentrate last?

Stored airtight in the fridge, concentrate stays fresh for about 7-10 days. Undiluted concentrate lasts longer than pre-diluted cold brew because the higher coffee content slows flavor degradation. Diluted, ready-to-drink cold brew is best consumed within 3-4 days.

By the Cold Brew Coffee Gear Guides Editorial Team · 4 min read

Home cold brew coffee equipment mistakes beginners make (and how to avoid them)

Cold brew looks foolproof: dump grounds in water, wait, drink. But the reason your homemade batch tastes like weak dishwater one day and bitter tannin sludge the next usually comes down to equipment and setup, not the beans. After making a few hundred liters at home, here are the mistakes that trip up almost everyone starting out, plus exactly how to fix them.

Mistake 1: Using a blade grinder (or pre-ground coffee)

The single biggest quality killer is grind consistency. A blade grinder chops beans into a chaotic mix of dust and boulders. The dust over-extracts and turns bitter; the boulders barely extract at all. You get muddy sediment and a flat flavor at the same time.

Cold brew wants a coarse, even grind — think raw sugar or coarse sea salt, not powder. That requires a burr grinder.

What to buy

Budget: A manual burr grinder like the Timemore C2 or 1Zpresso Q2 (~$40-70) makes excellent coarse grounds. Fine for one batch a week.
Volume brewers: An electric burr grinder like the Baratza Encore (~$170) saves your wrist if you're grinding 200g+ at a time.

If you must use pre-ground, buy it labeled "coarse" or "French press," and use it within a couple of weeks.

Mistake 2: Guessing the coffee-to-water ratio

Eyeballing scoops is why results swing wildly. Cold brew is brewed as a concentrate, then diluted, so the ratio matters more here than in any other method.

Cold brew concentrate recipe (by weight)

Use a 1:5 ratio for concentrate — 200g coffee to 1,000g (1 liter) water. Steep 16-18 hours at room temperature or 18-24 hours in the fridge, then dilute the finished concentrate 1:1 with water, milk, or over ice when serving.

Want ready-to-drink straight from the jar? Brew at 1:8 (125g coffee to 1 liter) and skip dilution.

Cold brew vs iced coffee ratio — why they differ

Iced coffee is hot-brewed at a normal 1:16 ratio and poured over ice, so it's already drink-strength (and gets watered down by melting ice). Cold brew never touches hot water, extracts far less acidity, and is intentionally concentrated. Don't apply a drip-coffee ratio to a cold brew batch — you'll get something thin and forgettable. Weigh your coffee and water with a kitchen scale; volume measurements lie.

Mistake 3: Picking the wrong brewing vessel

The "best cold brew coffee maker" isn't one product — it's the one matching how much you drink and how much cleanup you tolerate.

Immersion + fine filter (best all-rounder): The OXO Good Grips Cold Brew Maker or a wide-mesh brewer like the Toddy produce clean, low-sediment concentrate. The Toddy makes big batches (up to 7 cups of concentrate) but the felt filter needs care.
Mason jar + nut-milk bag or paper filter (cheapest): A 1-liter jar and a reusable filter bag costs under $15 and works genuinely well. Line a fine mesh strainer with a paper filter for the final polish.
Bottle brewers (French-press style): The Hario Mizudashi or KINTO bottle steeps and stores in the same vessel — great for small kitchens, but capacity is limited (~600-1000ml).

Avoid gimmicky "rapid cold brew" gadgets that agitate for 10 minutes. They don't develop the same smooth flavor as a real long steep.

Mistake 4: Skipping the double filter

Sediment is the texture problem nobody warns you about. A single mesh strainer lets fine particles through, leaving a gritty layer at the bottom of your glass. The fix is a two-stage filter:

First pass: pour through a mesh strainer or nut-milk bag to remove the grounds. Don't squeeze the bag hard — it forces bitter fines into the liquid.
Second pass: run it through a paper coffee filter or a reusable cloth filter for a clean, syrupy concentrate.

This second pass takes 10 extra minutes and completely transforms the mouthfeel.

Mistake 5: Wrong water, wrong temperature, wrong time

Small variables add up:

Water: Use filtered water. Heavy chlorine or very hard tap water dulls flavor and shows up more in cold brew than hot coffee.
Temperature: Room-temperature steeping extracts faster (16-18 hrs); fridge steeping is slower and more forgiving (18-24 hrs). Going past ~24 hours risks over-extraction and woody, papery notes.
Not stirring at the start: Dry grounds float. Give the mixture one good stir at minute zero so every ground is saturated, then leave it alone.

Your quick pre-brew checklist

Grinder: Burr, set to coarse (raw-sugar texture)
Ratio: 1:5 by weight for concentrate, 1:8 for ready-to-drink
Scale: Weigh both coffee and water — no scoops
Filtered water, stirred once at the start
Steep 16-18 hrs room temp, or 18-24 hrs in fridge
Double filter: mesh first, paper second
Store concentrate airtight; use within 7-10 days

The takeaway

Great home cold brew isn't about expensive gear — it's about controlling three things: a consistent coarse grind, an accurate weighed ratio, and clean filtration. Nail those with a $50 burr grinder, a $10 jar-and-filter setup, and a kitchen scale, and you'll out-brew most coffee shops for a fraction of the price. Dial in one variable at a time, keep notes on your ratios and steep times, and within three or four batches you'll have a repeatable recipe you actually look forward to.