Why is my espresso running too fast or too slow?

Shot time is a symptom, not a setting. What it tells you about your grind, your dose and your tamp — and which one to change first.

Difficulty: intermediate
Time: 15 min
Read: 3 min

Short answer

Grind finer if the shot runs fast, coarser if it runs slow, and change only that. A double should take roughly 25-30 seconds to produce about twice the weight of the dry coffee. Everything else is downstream of the grind.

Espresso is water forced through a compacted bed of coffee, and the flow rate is decided almost entirely by how fine that coffee is. A fast shot means the water found it too easy; a slow one means it struggled. The temptation is to adjust several things at once, which makes it impossible to know what worked.

What you'll need

Grinder with fine adjustment
Scales
Timer (optional)

Step by step

Weigh the dose and the output.Time alone tells you little. A typical target is 18g of dry coffee producing 36g of liquid in 25-30 seconds. Without weights you are guessing.
Change the grind only, one step at a time.Fast shot, finer grind. Slow shot, coarser. Change nothing else until the timing is close — otherwise you cannot attribute the improvement.
Purge a little coffee after each adjustment.Grinders hold grounds from the previous setting in the burr chamber. The first few grams after a change are a mixture of both settings.
Check your tamp is level, not harder.Tamping harder is not a fix for a fast shot. An uneven tamp is a real problem, because water channels through the thin side and the rest is barely extracted.
Distribute the grounds before tamping.Tap or level the basket so the bed is even. Most 'the grind is wrong' problems are actually uneven distribution.
Reassess after the beans have rested.Very fresh beans release carbon dioxide that disrupts flow. Coffee is usually most predictable between about a week and a month after roasting.

Tips

Change one variable at a time and write down what you did. Espresso rewards notes more than instinct.
Grind settings drift as burrs warm up and as a bag of beans ages. A setting that worked last week is a starting point, not a constant.

Common mistakes

Adjusting grind, dose and tamp together — You learn nothing. If it improves you do not know why, and if it worsens you cannot go back.
Tamping harder to slow a fast shot — Beyond firm and level, extra pressure changes almost nothing. The grind is what controls flow.

If it doesn't work

Shot gushes in under 15 seconds

Cause: Grind far too coarse, or dose too low for the basket — Fix: Grind noticeably finer and check the basket is properly full. A loose bed lets water through almost unimpeded.

Nothing comes out, or it drips for a minute

Cause: Grind too fine, or tamped into a solid plug — Fix: Grind coarser. If it persists, reduce the dose slightly — an overfilled basket compresses against the shower screen.

One side of the puck is soaked, the other dry

Cause: Uneven distribution or an angled tamp — Fix: Level the grounds before tamping and press straight down. This is channelling and no grind change will fix it.

Timing is right but the taste is thin

Cause: The ratio is off, not the flow — Fix: Check output weight. A correctly-timed shot that produces too much liquid is over-extracted and watery.

Questions people ask

How long should an espresso shot take?

Roughly 25-30 seconds for a double, producing about twice the weight of the dry coffee. Treat it as a diagnostic range rather than a target to hit exactly — taste decides.

Why did my grind setting stop working?

Beans age and release less gas, burrs warm up, and humidity changes. Small drift is normal and expected; re-dial rather than assuming something has broken.