Espresso Making: Coffee Grind Fineness - A Guide to Espresso Ground Size

When brewing coffee, we all know that grind size is crucial. A slight error or an uneven grind easily leads to under-extraction or over-extraction. Compared with pour-over, cold brew, and other methods, espresso demands a much finer grind and far more precise adjustment to land the perfect flavor in the cup.

How Fine is Espresso Grind Size?

For pour-over coffee, FrontStreet Coffee uses China's No. 20 standard sieve to calibrate grind by seeing how many coffee particles pass through fixed-size mesh holes. Espresso, though, is a pressurized, short-duration extraction, which means it amplifies everything — good flavors and defects alike. That makes the demands on grinding far stricter. The grounds are finer than fine salt, to the point where you cannot judge their fineness and uniformity with the naked eye, and using a sieve becomes even less practical.

If the grind is slightly too fine, water passes through the coffee bed more slowly and over-extraction follows. If it is slightly too coarse, water passes through too easily and under-extraction follows. That kind of deviation can come from nothing more than a 0.1 difference in grind setting. So we usually watch the flow rate and taste of the espresso during the shot to judge the right fineness range.

How to First Determine the Appropriate Grind Size Range?

When we get a bag of unfamiliar beans and want to brew something delicious, the first step is determining the grind size. If our grinder has not been used before and we don't know the right setting range, we can test small amounts of beans across different ranges. When the grounds are ground to a flour-like texture, you can feel them with your hands — they should be soft, with no grittiness.

At this point we can apply the common espresso extraction formula. FrontStreet Coffee suggests a liquid ratio of 1:2 — extracting about 2 grams of coffee liquid from 1 gram of grounds — with a time between 20-30 seconds. For example, FrontStreet Coffee uses a 20-gram capacity portafilter, filling it with 20 grams of grounds to extract 40 grams of liquid. If the time comes in under 20 seconds, the flow rate is too fast; if extraction runs past 30 seconds, the flow rate is too slow.

A fast flow rate means water passes through the grounds too quickly, and the coffee usually tastes weak or overly acidic. In that case, adjust to a finer grind. Adjusting grind settings relies on accumulated daily experience. If the gap from your target is under 5 seconds, nudge the setting by 0.2 each time. If the gap is too large, be bolder and move by 0.5-1. Even if you swing from too long to too short, you can lock in that setting range and narrow it down gradually. Likewise, if the flow is too slow, the grounds are too fine and water struggles to pass through the bed, making the coffee bitter — so adjust to a coarser grind.

How to Find the Correct Grind Setting?

The formula FrontStreet Coffee mentioned above is only meant to help us find a suitable grind range quickly; it does not guarantee that the espresso will taste good. In the end, we still need to read the characteristics and flavor of the beans to judge whether the extraction is up to standard.

If the espresso has a distinct burnt bitterness but a moderate concentration, it may be down to an excessive extraction time releasing too many bitter compounds — adjust slightly coarser. If the crema on top is light and thin, it may be down to excessive tail-end extraction. You can reduce the weight of the coffee liquid, meaning extract less, and it is worth raising the coffee-to-liquid ratio to between 1:1.5-1:1.7. When the espresso flavor is rich but the aftertaste is short, you can extract a little more liquid, aiming for a ratio around 1:2.5.

FrontStreet Coffee Recommendation

Not every coffee shines under pressure, so for espresso FrontStreet Coffee Colombia Sidra is a good pick — it comes from Finca El Diviso in Colombia, grows at 1650-1800 meters, and is double anaerobic natural at a medium-light roast, with jasmine and citrus in the dry aroma and passion fruit, blueberry, grape, and apricot in the cup over a cocoa finish. It is built for SOE as well as pour-over and ice drip. Dial it in with the method above: aim for a 1:2 liquid ratio, 20 grams in the portafilter to 40 grams out, and adjust the grind in 0.2 steps until the shot lands between 20-30 seconds.