Grams in, grams out, and why volume stopped mattering
For a long time espresso was measured in ounces of liquid — a 1-oz shot, a 2-oz double. Then somebody pointed out that a shot is mostly crema (foam) and the volume varies with grind, temperature, and pressure. Weighing the actual liquid is more consistent, and every good coffee shop now runs on grams.
A modern espresso pull has three numbers: dose (grams of dry coffee in the basket), yield (grams of liquid espresso in the cup), and time (seconds from pump start to pump stop). The ratio yield/dose is what people mean by '1:2' or '1:2.5'. A double shot pulled at 18 g in and 36 g out over 28 seconds is the standard modern reference — sometimes called a 'normale'.
Why ratios not ounces
Crema is variable. A fresh coffee produces a big frothy crema; the same shot two weeks later produces less. If you pull to volume you're pulling different amounts of actual coffee liquid each time. Weight ignores the foam and measures what's actually there.
The ratio dial
1:1 (18 g → 18 g) = ristretto, intense, syrupy, often used for milk drinks in Italy. 1:2 (18 g → 36 g) = normale, most common. 1:2.5 to 1:3 = lungo, more extraction, brighter, favored for lighter roasts and modern specialty coffee. Beyond 1:3 you get into filter-coffee territory of extraction and it usually tastes thin.
The other conversions
1 oz of espresso ≈ 30 g (density ~ 1.05 g/mL, close enough). So the old '1 oz shot' was roughly a 1:1.7 pull at an 18 g dose. Modern 'double' recipes deliver more liquid than the old US restaurant double.
Recap
Espresso is dose:yield in grams, timed. Put a scale on the drip tray. Volume is a legacy unit that hides variation.
Try the converters mentioned in this article
FAQ
Do I need a fancy scale?+
Any 0.1 g resolution scale that fits under a portafilter works. Timing can be a phone stopwatch.
Why 18 g?+
That's a common double basket size. 14, 16, 20, 22 g baskets all exist; match dose to basket then apply the ratio.
This article was written by The Turbo Unit Converter engineering desk (Applied metrology & engineering units) and last reviewed on 2026-07-23 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.