Ben Mitchell explores what the size of a double espresso says about the changing nature of the coffee industry.

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Coffee is a dynamic industry, in the sense that it involves countless people, all brewing, drinking, and innovating in their own unique ways. As specialty coffee continues to focus on quality and sustainability, certain assumptions about the way we consume coffee are coming into question.

For instance, in many places around the world, drinks like cappuccinos, flat whites, and lattes are served with what’s known as a “double shot” of espresso. Despite the wide prevalence of this unit of measurement, however, there seems to be little consensus on what it actually entails.

As such, if a customer somehow travelled ten years back in time and ordered a double espresso, what they’d receive might look very different to any sort of modern standard.

Ten years ago, volumetrics was a serious buzzword in the coffee community. Put simply, coffee was dosed using the same increments detailed on the side of a hot chocolate tub: heaped teaspoons.

Effectively, this was – and still is – an easy way to measure out a relatively consistent amount of coffee. Furthermore, volume is also used to quantify the amount of water pushed through your puck of coffee, also referred to as the yield. Traditionally, a double espresso would equate to 60ml (2oz) of liquid. Today, that’s not set in stone.

Many baristas and prosumers have come to understand that crema production can vary wildly when brewing espresso. Typically, robusta will produce more crema than arabica, and a medium roast coffee more than a light roast.

Likewise, a coffee roasted a week ago will produce more crema than a coffee roasted a month ago, and a freshly pulled espresso will contain more crema than an espresso left to settle for a few minutes.

Measuring by volume is difficult enough when judging with the human eye, and the variability of crema complicates the issue further.

In response, modern baristas have adopted the zealous use of highly-sensitive scales, with grams replacing millilitres. As such, the way we perceive a double espresso has shifted, too.

Is there an industry standard?

The idea of a double espresso is so unregulated that it can differ from one coffee shop to another. Numerous definitions and brew guidelines continue to confuse both baristas and customers.

For example, the Italian words ristretto, normale, and lungo drift in and out of use in coffee culture. At one stage, Australian cafés began pulling 1:1 and 1:1.5 shots, and suddenly ristretto was back on the scene. These days, normale denotes a brew ratio of 1:2-1:2.5, and a lungo is 1:3-1:4.

These words describe brew ratios, but many wrongly interpret them as measurements of espresso shot volume.

To a certain extent, the size of an espresso machine’s filter basket provides a rough parameter for the amount of ground coffee to be used. Generally speaking, single shot baskets hold 7-10g of coffee, double shot baskets 16-21g, and triple shot baskets 21-24g.

Double shot baskets are the standard in the UK. As such, to serve a single espresso, the barista may brew using a double shot basket and serve half the shot.

However, while basket size may allude to the amount of brewed coffee yielded, it’s the recipe that truly dictates yield. At a fundamental level, this is because different coffees possess different characteristics that affect the brewing process.

For example, a dense, dark roasted Brazilian coffee may require an 18g:36g coffee-to-water ratio to yield a properly extracted double shot, while a lighter, more porous East African coffee may require a longer brew ratio of 18g:42g. Here, the focus is on the quality of the resulting brew, not necessarily the volume yielded.

Using the appropriate basket size relative to the amount of ground coffee is important because it affects puck extraction, yet it cannot define the size of our double espresso because it does not define yielded coffee.

Less frequently, espresso is measured by its caffeine content, with a double typically assumed to contain around 60mg of the stimulant. In this case, total dissolved solids (TDS) and extraction yield (EY) are the metrics used to measure the amount of soluble material the water has extracted from the ground coffee.

A standard espresso might typically have an 8-12% TDS with an 18-22% EY. These measurements may be helpful to understand the chemical structure of your espresso, but they are metrics of proportion, meaning they give no further insight into how the size of a double espresso could be defined.

Generalising even further, the standard double espresso is considered to be 18g of ground coffee in, and 36g of liquid coffee out, brewed for between 25-32 seconds using 92-96ºC degree water and nine bars of pressure. 

Clearing up the confusion

As equipment gets more sophisticated, more and more coffee professionals are trying to push extraction towards a 1:3 ratio. However, this requires proper pre-infusion, excellent puck preparation, and the use of pressure and flow profiling, all of which help to prevent channelling.

Recipes are designed to get the best qualities out of each coffee, but it’s this very practice that makes it virtually impossible to create a standard for a double espresso.

Ultimately, while standards may differ between shops, the key is to create consistency, which is one of the many factors that brings customers back. By manipulating controllable variables like dose size, grind size, and water temperature, a coffee shop will ensure all its baristas produce the best possible espresso shots time and time again.

Digital scales, puck de-clumping, and particle distribution can help baristas achieve this, but it also comes down to the type of equipment used. Modern espresso machines feature reliable machine volumetrics, pre-infusion technology, and pressure and flow profiling, all of which aid the barista and prosumer while brewing.

For some customers, coffee menus can be confusing, and ordering can be a daunting prospect. Baristas that engage with customers help to create a level of understanding, clearing up any confusion over the perceived size of a double espresso.

If a customer orders an espresso, they will likely receive a double espresso as standard, when perhaps they would have liked a single instead. Baristas that engage with customers are more likely to anticipate misunderstandings like this.

Finally, it’s up to coffee shops to create menus that are legible and informative. Displaying the size of the cup that the drink is served in is one way to clear up confusion.

Any action taken to be as transparent as possible will likely be received with gratitude by customers, and ultimately, if they’re aware that the quality of the extraction means more than the volume, the size of a double espresso will become less and less relevant.