Foundational

International coffee units and measurements

Grams versus ounces, Celsius versus Fahrenheit, bar versus psi, and why a US cup, an imperial cup and a café serving size aren't the same volume.

CoffeeHQ's canonical basis: metric

CoffeeHQ's tools and recipes use grams, millilitres, and degrees Celsius as the canonical technical basis, since these are the units most brewing standards (including the SCA's) are defined in — with conversions offered for readers who think in other units.

Grams versus ounces

1 ounce (weight) ≈ 28.35 grams. Coffee dose is best measured by weight (a digital scale), not by volume (a scoop), since a "scoop" of coffee varies in weight depending on grind size and bean density.

"Cup" is genuinely ambiguous

A US customary cup is 236.6 ml; a metric cup (used in some countries' recipes) is 250 ml; an old imperial cup is about 284 ml — and a café's "regular" or "large" cup size is a business decision, not a standard unit at all. When a recipe says "one cup of water," check which convention it's using, or better, use millilitres/grams directly.

Celsius versus Fahrenheit

°F = (°C × 9/5) + 32. Common brewing temperatures: 90°C ≈ 194°F, 96°C ≈ 205°F.

Bar versus psi

1 bar ≈ 14.5 psi. Espresso is commonly brewed around 9 bar (≈130 psi) of pump pressure.

Regional serving-size differences

Typical café drink sizes (e.g. what counts as a "regular" coffee) vary by country and chain — see CoffeeHQ's international drink naming guide for how this interacts with drink names themselves.

Sources

SCA brewing and espresso standards — Specialty Coffee Association (SCA)