How to Make Cold Brew Coffee at Home: 1:8 Ratio

What Is Cold Brew Coffee?

Cold brew is coffee brewed by steeping coarsely ground coffee in cold or room-temperature water for an extended period — typically 12–24 hours. No heat is involved at any stage.

This matters more than most people realize. Heat speeds up the extraction of many acids and bitter compounds in hot-brewed coffee, so removing it changes what ends up in the cup.

The result is a coffee that's naturally sweeter, much lower in perceived acidity, and significantly smoother in body than any hot-brewed method. Cold brew isn't just coffee that's been chilled — it's a chemically distinct product.

Cold Brew vs Iced Coffee: Why They're Not the Same Thing

The distinction is simple: iced coffee is brewed hot and then cooled or poured over ice. Cold brew is never heated.

The practical implication: if you've tried iced coffee and found it sour or harsh after the ice melted, that's the hot-brewed acids coming through as the drink dilutes. Cold brew doesn't have this problem to the same degree because it contains fewer of those acids in the first place.

To understand how cold brew fits into the broader landscape of coffee drink differences, it helps to know that cold brew is effectively its own brewing category rather than a variant of drip or espresso.

What You Actually Need to Make Cold Brew at Home

You do not need a dedicated cold brew system to make excellent cold brew. The flavor difference is marginal: a system like the Toddy filters slightly faster and produces slightly less sediment, but the cups taste nearly identical.

The Minimum Setup

• Wide-mouth mason jar — 32 oz or larger. A French press also works well.
• Kitchen scale — ratio control is the single biggest variable. Volume measurements are unreliable for coffee.
• Burr grinder — set to coarse. A consistent burr grinder prevents fines that make filtering a nightmare and produce bitterness.
• Fine-mesh strainer lined with a paper coffee filter or two layers of cheesecloth.
• Filtered water — hard tap water will dull the flavor. It matters more in cold brew because there's no heat to work around mineral issues.

Optional Upgrades

• Dedicated cold brew maker (Oxo, Toddy, KitchenAid glass carafe) — faster filtering, slightly cleaner cup, less mess.
• Cold brew bag or sock filter — allows you to pull grounds out cleanly without pouring through a strainer.
• Glass storage bottles — 500ml swing-top bottles are ideal. Plastic absorbs coffee oils over time.

*Start with the mason jar method for your first few batches. Once you know the ratio and steep time that works for you, then decide if specialized equipment is worth buying.*

Choosing the Right Coffee for Cold Brew

Cold brew rewards good coffee more than almost any other method because it has no heat to mask defects. Robusta-heavy blends or low-grade dark roasts will produce harsh, earthy concentrates that no amount of dilution will fix.

Cold Brew Ratio: The Number That Changes Everything

The cold brew ratio is the weight of coffee grounds divided by the weight of water. It's the most important variable in cold brew, and it's where most recipes either make the process more complicated than it needs to be or give you a useless single-number recommendation without context.

One note: always measure by weight, not volume. "1 cup of ground coffee" can vary by 20–30g depending on grind size and how tightly the grounds are packed.

Cold Brew Coffee Recipe: Step-by-Step

This is a reliable, tested method for standard concentrate batches. It holds up well against more complex methods that use nitrogen flushing, specific water mineral profiles, and temperature-controlled environments.

1. Grind your coffee coarse — Set your burr grinder to its coarsest setting — coarser than you'd use for French press, even. The particles should look like coarse sea salt or raw sugar. Fines (fine coffee dust) are the enemy in cold brew: they pass through most filters, cloud the concentrate, and over-extract during the long steep. A blade grinder will create so many fines that filtering becomes a frustrating slog. If you're serious about making cold brew regularly, a decent burr grinder is the one piece of equipment worth investing in.
2. Weigh the coffee and water — Weigh out 100g of grounds and 800ml (800g) of cold filtered water. These amounts scale linearly — for a larger batch, use 200g coffee to 1600ml water, and so on. Filtered water makes a real difference in cold brew. The flat mineral profile of filtered water lets the coffee's natural sweetness come through without interference from chlorine or heavy mineral content.
3. Combine and stir — Add grounds to your mason jar first, then pour the cold water over them slowly. Stir gently but thoroughly for 30–45 seconds, making sure every particle is saturated. Dry pockets of grounds at the top won't extract and you'll lose yield. Don't be aggressive — you're not trying to extract anything yet, just ensuring even saturation before the long steep. *Tip: Pour in circular motions from the outside inward, like you're doing a pour over bloom — it helps wet grounds evenly.*
4. Seal and refrigerate for 18 hours — Seal the jar tightly and place it in the refrigerator. Write the start time on a sticky note if you have a tendency to forget. The fridge temperature (~4°C / 39°F) slows extraction and produces a smoother, cleaner result than room-temperature cold brew. You can steep at room temperature and reduce time to 8–12 hours, but the flavor profile shifts — slightly more acidic, slightly less clean. The fridge method is the better choice for almost every batch.
5. Filter the cold brew — This step trips up more people than any other. Set a fine-mesh strainer over a large bowl or pitcher. Line it with a paper coffee filter (Chemex or standard drip size both work) or two layers of dampened cheesecloth. Pour the steeped cold brew slowly into the strainer. Don't stir or press the grounds — gravity-fed filtering produces a clearer concentrate. Expect this to take 10–20 minutes depending on how coarse your grind is and how saturated your filter is. *If filtering is very slow, your grind was too fine. Adjust coarser next batch.*
6. Store in a sealed glass container — Transfer the filtered concentrate to a clean glass container — mason jars, swing-top bottles, or any glass bottle with a seal works. Label it with the date. Concentrate keeps for 10–14 days refrigerated. Plastic containers are fine if that's all you have, but glass is preferable for long-term storage: plastic can absorb coffee oils and impart off-flavors to future batches if the container is reused.

Cold Brew Steep Time: Why 18 Hours Outperforms 12 and 24

Cold brew steep time is the variable people spend the most energy debating, but the answer is simpler than most guides make it.

Cold Brew Concentrate vs Regular Cold Brew: Which Should You Make?

Cold brew concentrate (brewed at 1:8) is essentially a coffee stock — like a stock cube rather than a bowl of soup. You dilute it at the point of serving.

The recommendation for most home brewers: make concentrate. The flexibility to serve at different strengths, and the longer shelf life, make it the better option for almost every household use case.

How to Serve Cold Brew

Cold brew is versatile at serving. Once you have a jar of concentrate in the fridge, you have the base for a range of drinks that take under a minute to prepare.

• Cold Brew Over Ice — Fill a tall glass with ice. Add 2–3 oz cold brew concentrate, top with 2–3 oz cold filtered water. Stir briefly. Tastes cleaner than café cold brew because you control the ratio and the freshness of the concentrate.
• Cold Brew Latte — Fill a glass with ice. Add 2 oz concentrate, then pour 2–4 oz cold oat milk or whole milk over it. Don't stir — watch the milk cascade through the dark concentrate. Naturally sweet, no sugar needed if your beans are good.
• Cold Brew Tonic — This surprises people the first time. 2 oz concentrate over ice, topped with 4 oz quality tonic water (Fever-Tree works well). The bitterness of the tonic complements the sweetness of cold brew in a way that's refreshing in summer.
• Warm Cold Brew (Hybrid) — Don't heat the concentrate directly — it changes the chemistry. Instead, add concentrate to a mug and top with hot water at a 1:3 ratio. You get a warm drink with cold brew's low-acid profile. Useful for cold mornings when you want the smooth flavor without iced coffee.

One serving note: always use large ice cubes or spherical ice for cold brew. Small ice melts fast and dilutes the drink within minutes.

Common Cold Brew Mistakes (And How to Fix Them)

These are the mistakes that come up most consistently for people trying cold brew for the first time:

Your First Batch Starts Tonight

Cold brew is one of the easiest methods to master and one of the most consistent to reproduce once you nail the ratio. 100g coarse coffee, 800ml filtered water, 18 hours in the fridge — that's all it takes to produce a concentrate that compares well with most café cold brew at a fraction of the cost.

Equipment Worth a Look

If this guide has you thinking about gear, these are reviewed products on this site that fit the topic. Prices and availability change, so check the current listing before you buy.