Measuring coffee by volume is inconsistent because as coffee ages, the amount of crema also varies. Typically we define an extraction by saying something like 30 mL in 25 seconds or 30 mL in 20 seconds. In science this is known as a volumetric flow rate, i.e. change in volume over change in time. For espresso the units would be in mL/s. This is highly inaccurate due to the fact that a volume reading is typically done by eyeballing in a graduated shot glass, which is inaccurate by its very nature.

Mass is a much more reliable unit to measure our extractions. We could perhaps use a mass flow rate, i.e. change in mass over change in time for the espresso in our demitasses, leading to a measurement in grams/s. However, volumetric flow rates and mass flow rates doesnt give us much insight to the extraction were trying to describe. We need other pieces of key information such as dosage and espresso mass. In other words, describing our espresso in terms of flow rates is useless. Enter the Espresso Brewing Formula.

The Espresso Brew Formula or EBF is a ratio of the mass of ground coffee to the mass of the brewed espresso.

What the EBF does not specify is grind setting and hence extraction time, like the volumetric flow rate. This however can be recitfied by appending such information on top of the EBF. This would then almost fully describe an extraction of espresso for the purposes of CS members sharing information and seeking assistance.

eg: EBF (%) = 60 % - 18 gram dose, 30 gram espresso, 22 second extraction, 92 degrees C. Another person trying to replicate your extraction has almost all the information they need to try and achieve a similar extraction.

I like drinking my espressos anywhere between 55-62 % EBF. 65% and above is ristretto range - underextracted sour coffee.

To end this post, for those of you who are asking for assistance in trying to diagnose your extractions, please fully describe your extraction by specifying:

1) Dosage - how much coffee you put in the basket in grams

2) Espresso mass - how much the resulting liquid espresso weighs in grams

3) Extraction time - from the time you engage your pump to the time you turn it off in seconds

4) Temperature - if known

5) Roast date - if known

Volumetric flow rates will not help e.g. 25 mL in 30 seconds.

Your thoughts and comments are more than welcome. I hope we can change the way we talk about coffee by eradicating the use of volumes.

Mass is a much more reliable unit to measure our extractions. We could perhaps use a mass flow rate, i.e. change in mass over change in time for the espresso in our demitasses, leading to a measurement in grams/s. However, volumetric flow rates and mass flow rates doesnt give us much insight to the extraction were trying to describe. We need other pieces of key information such as dosage and espresso mass. In other words, describing our espresso in terms of flow rates is useless. Enter the Espresso Brewing Formula.

The Espresso Brew Formula or EBF is a ratio of the mass of ground coffee to the mass of the brewed espresso.

**EBF (%) = 100 * (dosage in grams)/(espresso mass in grams)**What the EBF does not specify is grind setting and hence extraction time, like the volumetric flow rate. This however can be recitfied by appending such information on top of the EBF. This would then almost fully describe an extraction of espresso for the purposes of CS members sharing information and seeking assistance.

eg: EBF (%) = 60 % - 18 gram dose, 30 gram espresso, 22 second extraction, 92 degrees C. Another person trying to replicate your extraction has almost all the information they need to try and achieve a similar extraction.

I like drinking my espressos anywhere between 55-62 % EBF. 65% and above is ristretto range - underextracted sour coffee.

To end this post, for those of you who are asking for assistance in trying to diagnose your extractions, please fully describe your extraction by specifying:

1) Dosage - how much coffee you put in the basket in grams

2) Espresso mass - how much the resulting liquid espresso weighs in grams

3) Extraction time - from the time you engage your pump to the time you turn it off in seconds

4) Temperature - if known

5) Roast date - if known

Volumetric flow rates will not help e.g. 25 mL in 30 seconds.

Your thoughts and comments are more than welcome. I hope we can change the way we talk about coffee by eradicating the use of volumes.

## Comment