The single simplest upgrade to your home coffee isn't new gear — it's a kitchen scale. The coffee-to-water ratio — how many grams of coffee per milliliters of water — is why the same "recipe" can turn out different twice in a row if you're eyeballing it with a spoon.
What the "golden ratio" is
The Specialty Coffee Association (SCA) recommends, for filter coffee, roughly 55 grams of coffee per liter of water — about 1:18. In practice, most baristas work comfortably between 1:15 (stronger) and 1:18 (lighter), depending on taste preference and the roast used.
How to calculate it
The formula is simple: coffee weight × ratio = milliliters of water. For 20g of coffee at a 1:16 ratio, you need 320ml of water (20 × 16). Always weigh the coffee before grinding, and measure water either by scale or a graduated container — eyeballing it with a mug introduces 20-30% variation.
Recommended ratios by method
- Espresso: about 1:2 (e.g. 18g ground coffee → 36g of liquid in the cup) — the most concentrated method.
- V60, Chemex, classic filter: 1:15 to 1:17, depending on how strong you want it.
- French press: 1:12 to 1:15 — slightly stronger than filter, due to its fuller body.
- Moka pot: roughly 1:10, though the chamber is usually filled completely, so the ratio follows from the pot's size.
- Cold brew: brewed much more concentrated, around 1:8, then the resulting concentrate is diluted with water or ice, usually 1:1.
Why it matters more than it seems
Too "weak" a ratio (lots of water, little coffee) gives an under-extracted, sour, thin cup. Too "strong" a ratio can mask the flaws of a mediocre roast, but also over-extracts good coffee, bringing bitterness. A scale removes the guesswork and lets you repeat a cup you got right.
See also our guides for moka pot and French press, where we apply these exact ratios step by step.