Brewing basics, 5 minute read, October 2026

Espresso basics for beginners

18 grams in, 36 grams out, about 30 seconds. Here's how espresso works and how to dial it in.

Espresso is coffee made by forcing hot water through finely ground, tightly packed coffee at high pressure, usually about 9 bar. It makes a small, concentrated shot with a layer of foam called crema, and it's the base for lattes, cappuccinos, and Americanos. It's also the least forgiving method on this site. Here's what you need to know before you spend money on a machine.

What you need

• An espresso machine that can reach about 9 bar of pressure
• A grinder that can make a fine, consistent grind. Clive Coffee, a retailer, argues the grinder matters more than the machine for home espresso, and many coffee people agree.
• A scale that reads to 0.1 g and a timer
• Fresh whole beans, roasted for espresso or any bean you like

Treat these as a starting point, not a rule. The Specialty Coffee Association's older definition calls for 14 to 18 g in a double and 20 to 30 seconds, and a 2017 survey of 275 baristas it cites found most shots in the 25 to 30 second range, averaging near 1:2. Different sources give time windows from 20 to 35 seconds.

Dial it in

Dialing in means adjusting until a shot tastes balanced. The simple rule is to lock the dose and the yield, and change only the grind. Weigh 18 g in and stop at 36 g out. Then read the time:

• Too fast (under about 20 seconds), and sour or thin: grind finer.
• Too slow (over about 35 seconds), and bitter or harsh: grind coarser.

Clive Coffee puts it this way: time is a symptom, not a cause. If you change the grind, the time follows.

Roast level changes the target

Per Clive Coffee, lighter roasts often need a longer ratio, about 1:2.5 to 1:3 (18 g in, 45 to 54 g out), while darker roasts do better with a shorter ratio, about 1:1.5 to 1:1.8 (18 g in, 27 to 32 g out). Try the standard 1:2 first, then adjust.

Step by step

1. Warm up. Turn the machine on and give it time to heat fully. Run a blank shot through the portafilter to warm it.
2. Weigh and grind. Grind about 18 g into the portafilter basket and level it.
3. Tamp. Press the coffee down firmly and evenly so the surface is flat.
4. Brew. Lock in the portafilter, put the cup on the scale, and start the shot and the timer together. Stop when the scale reads about 36 g.
5. Taste and adjust. Change the grind, not the dose, and pull another.

What about moka pots and AeroPresses?

A moka pot and an AeroPress both make strong, concentrated coffee, but neither makes true espresso. AeroPress, the maker, puts the moka pot at about 1 to 2 bar and the AeroPress at about 2 bar, against 9 bar for an espresso machine. That is the manufacturer's comparison and the numbers are approximate. Both are good, cheap ways to get a strong cup. See our guides to the moka pot and the AeroPress.

Tips that make a bigger difference than gear

• Weigh everything. Dose and yield by weight make shots repeatable.
• Buy fresh beans, then wait a few days. Very fresh beans are full of gas and can make uneven shots. Sources vary, but about a week after roasting is a common sweet spot for espresso.
• Keep it clean. Old coffee oil makes shots bitter. Wipe the basket and the group head, and follow your machine's cleaning routine.
• Be patient. Most beginners need a few tries and a few wasted shots to dial in a new bag.

This guide covers basics, not machine buying advice. Machines, grinders, and beans all vary, and it leaves out how the pump and boiler work. Based on published sources, including Clive Coffee, Complete Home Barista, the Specialty Coffee Association, and AeroPress.