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Understanding Coffee-to-Water Ratios (and Why They Matter)
A recipe says "use a 1:16 ratio." Another says "60 grams per litre." A third just says "two tablespoons per cup." They're all trying to say the same thing, and they're all useless if you don't understand what a ratio actually controls. This guide breaks it down in plain language so you can adjust your brew strength with confidence instead of guessing.
What the Numbers Mean
A coffee-to-water ratio tells you how much coffee to use for a given amount of water. It's always expressed as coffee first, water second.
- 1:15 means 1 gram of coffee for every 15 grams of water. For a single cup: 15g coffee to 225g water.
- 1:16 means 1 gram of coffee for every 16 grams of water. For a single cup: 15g coffee to 240g water.
- 1:17 means 1 gram of coffee for every 17 grams of water. For a single cup: 15g coffee to 255g water.
The difference between 1:15 and 1:17 might look small on paper. In the cup, it's the difference between a rich, punchy espresso-like brew and a delicate, tea-like sipper. Both can be excellent. They're just different experiences.
Why You Should Weigh, Not Scoop
A "tablespoon" of coffee varies wildly depending on bean size, density, and roast level. A tablespoon of dense, light-roast Ethiopian beans weighs about 6 grams. The same tablespoon of puffy, dark-roast Sumatran beans might weigh only 4 grams. That 50% difference means your cup strength changes every time you switch beans, even if you use the exact same scoop.
A simple digital scale eliminates this problem entirely. Weigh 15 grams, and it's 15 grams regardless of the bean. Consistency is the foundation of good coffee, and the scale is what makes consistency possible.
The Standard Starting Points
The Specialty Coffee Association (SCA) recommends a ratio of 1:16.7 (55 grams of coffee per litre of water) as the "golden ratio" for filter coffee. This is a useful starting point, not a rule.
In practice, most pour-over brewers land somewhere between 1:15 and 1:17 depending on personal preference:
| Ratio | Character | Single Cup (15g dose) | Two Cups (30g dose) |
|---|---|---|---|
| 1:14 | Very strong, concentrated | 210g water | 420g water |
| 1:15 | Strong, full-bodied | 225g water | 450g water |
| 1:16 | Balanced (most common) | 240g water | 480g water |
| 1:17 | Light, delicate, complex | 255g water | 510g water |
| 1:18 | Very light, tea-like | 270g water | 540g water |
Adjusting Ratio by Roast Level
Darker roasts are more soluble. They give up their flavour quickly and easily, which means a 1:16 dark roast can taste stronger than a 1:15 light roast brewed the same way. Many experienced brewers use a tighter ratio (1:15 or even 1:14) for light roasts and a more open ratio (1:16 to 1:17) for dark roasts to compensate.
Read our roast level guide for more on how different roasts behave in a pour-over.
Ratio vs. Strength vs. Extraction
These three concepts are related but separate, and confusing them leads to frustrating results:
- Ratio controls concentration: how much coffee flavour exists in each sip. More coffee per water = stronger.
- Extraction controls which flavours you get. Under-extraction = sour. Over-extraction = bitter. Extraction is governed by grind size, temperature, and time.
- Strength is what you perceive in the cup: a combination of both. You can have a high-extraction, low-ratio cup (lots of flavour fully dissolved, but diluted) or a low-extraction, high-ratio cup (concentrated but sour).
This is why increasing the coffee dose doesn't fix sour coffee. If the beans are under-extracted, you just get more sour coffee in a smaller volume. Fix extraction (grind finer, increase temperature) first, then adjust ratio for preferred strength. See our recipe dialling guide for the complete framework.
Scaling Recipes Up and Down
Once you know your preferred ratio, scaling is simple maths. If you brew for two people, double the dose and the water. Three people? Triple it. The ratio stays the same.
The one adjustment: larger batches need a coarser grind. More coffee in the bed means more resistance to water flow. A 30-gram dose in a V60 02 will clog at the same grind setting that works perfectly for 15 grams. Go 2 to 3 clicks coarser when you double the dose, and use a larger dripper or a Chemex for batches over 400 grams total.