How to Use Our Brew Ratio Calculator (And Why Ratios Matter)

You've probably seen coffee recipes that say things like "use a 1:16 ratio" or "15g to 250ml" and wondered what that actually means, and how to scale it when you're brewing for two people instead of one.

That's exactly why we built the Brew Ratio Calculator. Pick your method, set your dose, choose how many cups, and it returns the exact coffee weight, water volume, temperature, grind size, and brew time for that method. No mental math, no guessing.

Before you start plugging in numbers, it helps to understand why ratios matter and where the standard numbers come from.

What Is a Brew Ratio?

A brew ratio is the relationship between the weight of your coffee grounds and the weight of your brew water, written as 1:X, where X is grams of water per gram of coffee. Baking calls this a baker's percentage; specialty coffee calls it a brew ratio, but the math is identical: everything is measured against the coffee dose.

Three reference points:

• 1:16 means 1 gram of coffee for every 16 grams of water, the global default for pour over.
• 1:2 (espresso) means 1 gram of dry coffee produces roughly 2 grams of liquid shot.
• 1:5 (cold brew concentrate) is a much stronger steep, meant to be diluted 1:1 with water or milk before drinking.

The ratio sets the strength of the cup independent of roast or bean choice. A tighter ratio like 1:12 produces a heavier, more concentrated cup. A looser ratio like 1:17 produces a lighter, more tea-like cup. Both can be "correct"; they're just different targets.

The Standard Ratios

Every brew method has a sweet spot shaped by contact time and pressure. Here's what the Brew Ratio Calculator uses as its defaults, the ratios that produce a balanced cup for most people, most beans, most of the time:

How to Use the Calculator

The Brew Ratio Calculator takes about 10 seconds to run:

1. Pick your brew method. Tap one of six options: espresso, pour over, French press, AeroPress, cold brew, or moka pot.
2. Set your dose. How many grams of coffee per cup? The default is 18g, which works for most methods. Adjust up or down by 1-2g if you prefer it stronger or lighter.
3. Choose your cups. Brewing for two? Three? The calculator scales the dose and water proportionally, no manual multiplication.

The output shows total coffee weight, water volume in both ml and oz, plus recommended water temperature, grind size, and brew time for that specific method.

Scaling Examples

Here's how the same ratios play out across different brew sizes, from a single cup to a full French press carafe:

Notice the pattern: everything scales off the coffee dose. Double the coffee, double the water, and the ratio, and therefore the strength, stays constant. This is the entire reason the calculator exists: nobody wants to do that arithmetic three times a day.

When to Adjust the Ratio

The default ratios work for most coffees, but three variables push you off the standard:

• Bean origin. Light, fruity Ethiopian beans often taste better at 1:17 for pour over; a looser ratio lets delicate floral and citrus notes come through without over-concentrating. Dark roasts can handle a tighter 1:15 without turning harsh.
• Freshness. Beans past the 3-4 week mark off the roast date lose soluble aromatics and taste flatter. Dosing 1-2g higher compensates for the lost intensity.
• Personal taste. There's no single "correct" ratio, only starting points. If you consistently want it stronger, lower the ratio by one point (1:16 to 1:15). If it feels heavy or bitter, raise it by one point instead.

Ratio vs. Grind Size: They Work Together

Ratio controls how much water touches the coffee; grind size controls how fast that water can extract flavor from it. Get the ratio right but the grind wrong, and the cup still tastes off, too sour if the grind is too coarse for the contact time, too bitter if it's too fine. For pour over at 1:16, a medium grind (similar to granulated sugar) paired with a 2:30-3:30 minute total brew time is the calibration point most guides start from. See the Espresso Grind Size Explained guide for how this plays out under pressure instead of gravity.

Ratio Mistakes Worth Avoiding

Three errors show up repeatedly when people move away from the calculator's defaults:

• Eyeballing water instead of weighing it. A "cup" of water can range from 200ml to 300ml depending on the mug. At 1:16, that swing alone moves an 18g dose from a 1:11 (too strong) to a 1:17 (too weak) without the coffee amount ever changing.
• Copying an espresso ratio onto drip coffee. 1:2 works under 9 bar of pressure in 25-30 seconds. Applied to a gravity-fed pour over, the same ratio produces a cup that's barely wetter than mud, because there's no pressure to force extraction that fast.
• Ignoring bloom water in the total. For pour over, the first 30-45 seconds of water (roughly 2x the coffee weight) is the bloom, meant to release trapped CO2. If you forget to count it toward your total 1:16, you'll end up pouring more water than planned and land closer to 1:18.

Going Deeper

Ratios are one piece of the puzzle. If you want to understand how grind size, water temperature, and timing work together for a specific method, these guides cover the full process:

• Pour Over Brewing Guide for Beginners, the full step-by-step process at 1:16.
• Espresso Grind Size Explained, how to dial in a 25-30 second shot.
• French Press: The No-Nonsense Guide, the 1:15 recipe and the four-minute steep.
• Grind Size Guide, matching particle size to brew method.
• Espresso Shot Journal, logging dose, yield, and time to dial in a recipe over multiple shots.