From Volume to Weight: The Modern Espresso Standard
The most significant change in espresso preparation over the last few decades is the move away from volumetric measurement (using milliliters) to gravimetric measurement (using grams). While a 30mL single shot and a 60mL double shot were once standard, the coffee industry has embraced a more precise approach. This is primarily because the golden-brown foam known as crema significantly impacts the total volume of a shot. A fresh bag of beans with plenty of trapped CO2 will produce much more crema than a stale bag, meaning a 60mL shot pulled from fresh beans will contain less actual liquid coffee than a 60mL shot pulled from older beans.
The Impact of Crema on Volume
To understand why volume is an unreliable metric, it helps to visualize the composition of an espresso shot. The shot consists of two main components: the liquid espresso and the crema. The crema is essentially a gas-in-liquid emulsion, full of air bubbles. This makes it less dense than the liquid coffee underneath. When you pour a shot and fill a 60mL shot glass, the total volume is an aggregate of both the dense liquid and the airy crema. Measuring by weight, however, provides a consistent and accurate way to determine the total mass of the extracted beverage, effectively removing the influence of crema. A target weight of 36 grams is a far more reliable indicator of a successful double shot than a target volume of 60mL.
The Rise of the Double Shot
For most modern cafés, the double espresso, or doppio, is the standard serving size. This shift occurred for both practical and qualitative reasons. For baristas, a double shot is easier to pull consistently because the larger, less-tapered double-shot baskets are more forgiving of minor inconsistencies in tamping and distribution. For customers, the double shot provides a richer, more robust flavor that stands up better in milk-based drinks like lattes and cappuccinos. Single shots are still available but often require a different portafilter basket, making them less common in high-volume settings.
Common Espresso Shots and Brew Ratios
Lists of standard espresso shots demonstrate the diversity within espresso preparation, all of which are increasingly defined by weight ratios for better consistency.
Common Espresso Variations:
- Ristretto: A "restricted" shot, using the same amount of coffee but less water, resulting in a more concentrated, sweeter, and thicker espresso. A common ratio is 1:1 or 1:1.5.
- Normale (Traditional Espresso): The standard shot, typically pulled with a 1:2 or 1:2.5 ratio of ground coffee to liquid espresso. This is what most people consider a classic single or double espresso.
- Lungo: A "long" shot, pulled with more water for a longer extraction time, resulting in a thinner, more bitter shot. Common ratios are 1:3 or 1:4. This can be more bitter due to over-extracting certain compounds.
The Brew Ratio Explained
The brew ratio is the key to reproducible espresso. It expresses the relationship between the weight of the dry coffee grounds (dose) and the weight of the final extracted liquid (yield). For example, a 1:2 ratio means that for every 1 gram of ground coffee, you aim to produce 2 grams of liquid espresso. A standard double shot might use 18 grams of coffee to produce a 36-gram yield. This method ensures that the barista can consistently replicate the same flavor profile, regardless of variables like bean freshness and crema volume.
Comparison Table: Volume vs. Weight
| Feature | Volume-Based Measurement (30mL / 60mL) | Weight-Based Measurement (Grams) |
|---|---|---|
| Primary Metric | Milliliters (mL) | Grams (g) |
| Consistency | Low, varies significantly based on crema and bean freshness. | High, provides a reliable and repeatable recipe. |
| Precision | Inaccurate, as crema volume is highly variable. | Highly accurate, accounts for liquid density regardless of crema. |
| Barista Adoption | Traditional, less common in modern specialty coffee shops. | Standard practice among professional and serious home baristas. |
| Focus | Achieving a specific visual fill level in a shot glass. | Reaching a specific mass of extracted coffee, focusing on taste profile. |
Conclusion
So, is espresso 30mL or 60mL? The simple answer is that both volumes were traditionally associated with single and double shots, respectively, but this is a misleading way to measure. The real answer for anyone seeking quality and consistency is to abandon the volume metric entirely. The modern espresso standard relies on weight-based ratios. By focusing on the weight of the coffee dose and the final extracted yield, baristas and home enthusiasts can achieve a perfect, repeatable shot every time. The 60mL double shot has become the de facto standard in most cafés, valued for its robust flavor and ease of preparation, but the exact volumetric output will always be secondary to the consistency offered by a precise weight ratio.
Understanding the importance of espresso brew ratios is a vital step in perfecting your brewing technique and moving beyond the outdated volume-based measurements of the past.
