How to make espresso at home: extraction, grind and temperature

A perfect espresso isn’t luck: it’s an equation of four variables — grind, dose, pressure and time — that you can learn to control. If your coffee tastes sour or bitter, the machine isn’t the problem: one of those variables is off. Here’s the method to find the sweet spot.

The four pillars of espresso

• Grind: coffee should be ground right before extraction. A fine grind (like sugar) slows the water and extracts more; a coarse one lets water through fast and extracts less. A burr grinder is essential: blade grinders can’t produce consistency.
• Dose: the amount of coffee in the portafilter. The standard is 18 grams for a double, but what matters is the ratio with the liquid that comes out.
• Pressure: 9 stable bars at the pump. You don’t need more; you need it to not fluctuate.
• Temperature: between 90 and 96 °C in the water that touches the coffee. Too cold, the espresso turns sour; too hot, bitter and burnt.

The base recipe

Start with this base and adjust from there:

1. 18 g of coffee, ground fine, in the portafilter.
2. Level and tamp: the coffee bed must be flat and even. One firm tap with the tamper and done — no brute force needed.
3. Extract 36 g of liquid (1:2 ratio) in 25-30 seconds from the first drop.

If the time is right, the flavor usually follows. If not, adjust the grind — not the dose or the pressure.

How to read your extraction

• Under 20 seconds, watery and sour coffee: grind too coarse. The water passed through quickly and extracted too little. Grind finer.
• Over 35 seconds, bitter and burnt coffee: grind too fine or dose too high. The water was in contact too long. Grind coarser.
• Channeling from one side of the portafilter: the coffee bed isn’t level or the tamper was crooked. Distribute better before tamping.
• Pale, bubbly crema: old or over-roasted coffee. Try fresh coffee.

The most common mistakes

• Pre-ground coffee: it loses aroma within days. Buy beans and grind at the moment.
• Changing two variables at once: adjust one thing per cup; if you change grind and dose together, you won’t know what worked.
• Tamping with brute force: tamp pressure matters less than leveling. One firm, even tap is enough.
• Ignoring the timer: the clock is your best tool. Without a reference time, you’re guessing.
• Rushing the warm-up: the machine needs 15-20 minutes to stabilize temperature, not 2.

When to adjust the recipe

• More acidic or lightly roasted coffee: try extracting a bit longer (1:2.5 ratio) to soften the acidity.
• Dark roast coffee: extract a little less (1:1.8) to avoid bitterness.
• Humid days or very fresh coffee: the grind can behave differently. Adjust fine or coarse based on extraction time.

FAQ

Do I need an expensive machine to make good espresso at home?

No. With a basic semi-automatic, a good burr grinder and fresh coffee you get a respectable espresso. Technique matters more than the machine.

How much coffee for an espresso?

For a double, 18 g of coffee and 36 g of liquid. For a single, half — though most modern portafilters are designed for doubles.

Why is my espresso sour?

Because it’s under-extracted: coarse grind, low dose or cold water. Grind finer and make sure the machine is hot.

Why is it bitter?

Over-extraction: grind too fine, too much time or water too hot. Grind coarser and reduce the time.

Does espresso have more caffeine than filter coffee?

By volume, yes; by cup served, no. A single espresso (30 ml) has less caffeine than a cup of filter coffee (200 ml).

Want to go further? Learn the difference between filter coffee and espresso to choose your method well, or discover how to pick the best espresso machine to get started.