Making a quality espresso at home is a bit more complicated than making excellent filter coffee.

Making an excellent espresso involves getting the following five variables right:

Brew ratio
Brewing temperature
Coffee grind size
Quantity of ground coffee you use
Brew time

Here we will go through how you can control all these variables with a basic espresso machine in order to create a drink that will rival anything you’d get from a coffee shop.

Brew Ratio: Weigh Out Your Ground Coffee and Final Espresso

One of the most important factors in making an excellent espresso is getting the correct brew ratio.

Brew ratio refers to the quantity of ground coffee that you brew with, compared to the quantity of liquid espresso that ends up in your cup.

Espresso should typically have a brew ratio of 1:1.3, but this ideal ratio can vary a bit depending on the type of coffee beans that you use.

The only way that you can accurately measure your brew ratio is by weighing out both your initial dose of ground coffee and the liquid that ends up in your cup.

You will need a scale to do this. Make sure that your scale is small enough to fit under your cup while making your espresso and that it can weigh to the nearest gram.

While it's easier to measure out your final espresso by volume, rather than weight, and to work on the assumption that one millilitre of liquid espresso weighs one gram, this is inaccurate due to the layer of crema that forms atop your espresso.
Crema adds significantly to the volume of your espresso without actually adding much extra liquid to it (crema is mainly air).

Therefore, to measure out your brew ratio accurately you will need to weigh both your ground and liquid coffee rather than measure it by some other means.

Do Not Exceed Maximum Coffee Dose For Your Portafilter Basket

The part of your espresso machine where your ground coffee sits during brewing is called its portafilter basket (the larger, detachable part of your espresso machine that holds your ground coffee is called its portafilter.)

Portafilter to the left and portafilter basket to the right

Each portafilter basket was designed to hold a maximum dose of ground coffee.

If you exceed this dose, then your brewing water will not be able to cover your ground coffee evenly.

This will create a bitter final drink as parts of your coffee bed that get the majority of the direct contact with your brewing water will become over extracted, and leech their harsher tasting compounds into your brewing water.

Your machine’s portafilter basket should have its maximum ground coffee capacity printed on its outside. If you cannot find it there, then it will definitely be in your machine’s instruction manual.

Use this as a fixed variable, and then use your desired brewing ratio (again 1:1.3 ground to liquid coffee is a good start) to determine how much water you want to brew with.

Brewing with less ground coffee than your portafilter basket’s maximum dose is not a problem.

Warm Up Your Portafilter Basket Before You Make Your First Espresso

Espresso should be brewed at a temperature between 92 and 96 degrees Celsius. If your brewing water is any cooler than this, then it will not extract the flavorful compounds out of your ground coffee efficiently enough and you will end up with a very flat tasting final drink.

While even a cheap espresso machine will likely heat your water up to this ideal brewing temperature, if your metal portafilter basket is cold then your water’s temperature will likely drop below 92 degrees Celsius when it hits your coffee bed.

You should therefore warm up your portafilter prior to making your espresso.

The easiest way to do this is to pull a blank shot, that is a shot without any ground coffee in your portafilter. The hot water should bring your portafilter basket to a temperature where it allows you to brew your espresso at 92-96 degrees Celsius.

At coffee shops, baristas tend to pull a handful of blank shots before making their first espresso. This probably is not necessary for a home machine, however more blank shots certainly won’t hurt.

Use a Pressurised Portafilter Basket if You are Brewing With Pre Ground Coffee

While I’d generally recommend making espresso with freshly ground coffee, you can still pull a decent shot using pre ground coffee if you use a pressurised portafilter basket.

Pressurised portafilter baskets differ from non-pressurised portafilter baskets in that the former only has one tiny hole where your liquid espresso can come out of. The latter has dozens, if not hundreds of these tiny holes.

The red circle shows the single hole on the pressurised portafilter basket on the right

Pressurised portafilter baskets are necessary for making good espresso with pre ground coffee because pre ground coffee tends to be ground coarsely (by espresso standards).

The coarser ground your coffee, the larger the spaces are between each individual grind.

Large spaces between grinds means that your brewing water will run through your coffee faster, resulting in less contact time between your coffee and water. This will lower extraction resulting in a dull tasting coffee.

The single hole on a pressurised portafilter acts as a bottleneck forcing your brewing water to sit in with your puck of ground coffee and therefore increasing the contact time between the two. This allows you to achieve a good extraction even with pre ground coffee.

If you use freshly ground coffee, and have a high quality burr grinder, then you will want to use a non pressurised portafilter basket as the ground coffee bed alone will offer enough resistance to your brewing water to allow for sufficient extraction.

If you have a lower quality grinder and grind your own beans then you still might want to use a pressurised portafilter basket.

A good way of testing whether you are better suited to a pressurised portafilter basket is by timing your shots. If your shots brew in anything under 22 seconds then you may want to switch to a pressurised portafilter basket, even if you grind your own beans.

Most espresso machines come with both pressurised and non pressurised portafilter baskets so you can make good espresso with both pre ground and freshly ground coffee.

Adjust Your Espressos Flavor By Changing Your Grind Size Setting

One of the biggest advantages of having your own coffee grinder is that the best way of fine tuning your espresso’s flavour is by adjusting your coffee’s grind size.

Trying to change your espresso’s flavour by adjusting the quantity of coffee that you use is like trying to hammer a nail with a sledgehammer. Even small changes in your brew ratio can make huge changes in your espresso’s final flavour.

You are far better off adjusting your espresso’s flavour by playing around with the grind size of your coffee.

As a general rule:

Coarser ground coffee will result in a more mild flavoured drink. Too coarse and your drink can be very dull tasting or a touch sour.

Finer ground coffee will result in a bolder drink. Too fine and your espresso will be harsh tasting.

The general best practice here is to keep grinding finer and finer until your espresso is too harsh tasting and then go back one setting. This should make as rich as coffee as possible without tasting harsh.

While making espresso is trickier than making coffee in a French press, it is a skill that can be mastered with a bit of practice.

So long as you meet the desired brew ratio, brewing temperature, and contact time between ground coffee and water, you should end up with an espresso that helps you hit the ground running every morning.

This article was written by Oli Baise, a barista who runs the coffee blog Drinky Coffee

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