What ratio should a beginner start with?

Use 1:5 by weight for concentrate — for example 200g coffee to 1,000g water — steeped 16–18 hours at room temperature. Dilute the finished concentrate 1:1 with water or milk to serve. It's forgiving and easy to adjust from there.

Can I use pre-ground coffee for cold brew?

You can, but most pre-ground coffee is medium-fine for drip and will make cloudy, over-extracted, bitter cold brew that clogs your filter. Ask for a coarse grind or grind your own to roughly the texture of coarse sea salt for the cleanest result.

How long does homemade cold brew last in the fridge?

Undiluted concentrate keeps well for up to 2 weeks in an airtight container. Once diluted with water it's best within about 3 days, and if you cut it with milk, treat it like dairy and drink within 1–2 days.

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

Best cold brew coffee ratio calculator — an honest buyer's guide

Most cold brew disappointments trace back to one thing: guessing the ratio. Too little coffee and you get watery brown water; too much and you burn cash on beans while over-extracting. This guide gives you actual numbers, a repeatable method, and honest advice on gear so your next batch is drinkable straight from the fridge.

How a cold brew ratio calculator actually works

A ratio calculator does simple math you can do on a napkin — but getting the reference points right is what matters. Cold brew is measured as coffee weight : water weight. The two ways people quote it:

Concentrate ratios (meant to be diluted): 1:4 to 1:8. A 1:5 ratio means 200g coffee to 1,000g (1L) water.
Ready-to-drink ratios (sip as-is): 1:12 to 1:16, similar strength to drip coffee.

A worked example

Say you want 1L of concentrate at 1:5. That's 1,000 ÷ 5 = 200g of coffee. To serve, you dilute concentrate 1:1 with water or milk, turning 1L of concentrate into ~2L of drinks. Prefer to skip the math? A calculator just lets you type your target volume and ratio, then spits out grams. The value is consistency: log the batch you loved and reproduce it exactly.

Steep time changes everything

Ratio and time work together. A 1:5 batch steeped 12 hours tastes very different from the same batch at 24 hours. Start at 1:5 for 16–18 hours at room temp, or 1:5 for 24 hours in the fridge. Adjust one variable at a time.

Cold brew vs iced coffee — they are not the same drink

People use these interchangeably and shouldn't. Iced coffee is hot-brewed coffee poured over ice — brewed in minutes, bright, acidic, and it can get watery as ice melts. Cold brew is steeped in cold or room-temp water for 12–24 hours, producing a smoother, lower-acid, naturally sweeter cup.

Concretely: cold brew is roughly 60–70% lower in perceived acidity than hot-brewed coffee because compounds like chlorogenic acids extract far less without heat. If your stomach hates regular coffee, cold brew is worth trying. If you want that crisp, tea-like brightness, iced pour-over wins.

Choosing the best cold brew coffee maker for home

You don't need to overspend. Here's what actually matters, from budget to premium:

Mason jar + nut milk bag ($10): Works fine for 1L batches. Messy to strain, but honest value.
Immersion pitcher with fine-mesh core (OXO, Takeya — $25–40): The sweet spot. Airtight, fridge-friendly, easy cleanup. Takeya's 1L makes about 4 diluted servings.
Slow drip tower ($150+): Beautiful, produces clean, complex brew over 3–5 hours. Overkill for most, but rewarding for enthusiasts.

What to look for

Filter fineness — cheap coarse mesh lets grounds through; look for stainless micro-mesh or paper-compatible baskets.
Capacity that matches your habit — a 1.6L maker if you drink daily.
Airtight lid for fridge storage up to 2 weeks.
Dishwasher-safe parts — coffee oils are a pain to hand-scrub.

Best beans for cold brew (and grind size)

Cold water is a gentle solvent, so bean choice and grind matter more than people expect.

Roast: Medium to medium-dark shine here. Try a Brazilian or Colombian for chocolate-nut sweetness. Very light roasts often taste sour and underextracted in cold brew.
Grind: Coarse, like raw sugar or coarse sea salt. Fine grinds slip through filters and turn bitter/sludgy.
Freshness: Beans 1–3 weeks off roast. Ultra-fresh beans can foam and stall extraction.

A reliable starter recipe

200g coarse-ground medium roast + 1,000g filtered water, room temp, 18 hours, stirred once at the start. Strain, refrigerate, dilute 1:1. This is a forgiving, crowd-pleasing baseline you can then tweak.

Cold brew filter replacement and maintenance

Filters are the most neglected part of the setup — and the reason many people quit. Fine-mesh stainless filters clog with oils over months and stop straining cleanly.

Deep clean weekly: soak the mesh in warm water with a dash of baking soda, then scrub with a soft brush.
Descale/degrease monthly: a diluted vinegar soak cuts coffee-oil buildup that dulls flavor.
Replace when: mesh is dented, grounds consistently pass through, or you smell rancid oils that survive washing. For most stainless cores, that's every 12–18 months of daily use.
Paper filter users: keep a stock of the correct size; a paper secondary filter dramatically clarifies concentrate for a cleaner cup.

Buy replacement filters that are OEM-matched to your maker — third-party mesh baskets often don't seal and let sediment through. A $6 replacement is cheaper than replacing the whole pitcher.

Takeaway

Start at a 1:5 concentrate ratio for 18 hours with coarse, medium-roast beans and a decent immersion pitcher. Use a calculator to lock in your grams so every batch is repeatable, keep your filter clean, and dilute to taste. Master those variables and you'll never buy a $6 café cold brew again — your homemade version will be better and cost about 50 cents a glass.