Tool
Espresso dial-in assistant
Describe the shot — dose, yield, time, how it tasted, what the flow looked like — and get a ranked list of what to change, in order, with what to hold constant.
Your shot
1:2.0 in 28s
That is 1.29 g per second, which is in a typical range. Flow bands are conventions — a shot inside one can still taste bad, and a shot outside one can be excellent.
Try this next
Check which basket you have: look for a single small hole on the underside.
A pressurised basket makes grind and distribution changes almost ineffective, and most entry-level machines ship with one. Knowing which you have decides whether anything below is worth trying.
Keep the same: Nothing — this is a check, not a change.
Watch for: Many fine holes across the whole underside means single-wall.
If that does not help
In order. Work down the list one change at a time — a suggestion that does not help has still told you something, by ruling a cause out.
Grind one or two steps finer.
The taste points at under-extraction, and grind is the variable with the largest effect on how far a shot extracts.
Keep the same: Dose and target yield, so the change can be attributed to the grind.
Watch the next shot through a bottomless portafilter.
Several espresso faults look identical in the cup and completely different at the basket. Watching the underside separates channelling from a simple grind problem in one shot.
Keep the same: Everything, for one diagnostic shot.
Where those numbers came from
Ratio = yield ÷ dose
36 ÷ 18 = 1:2.0
Flow rate = yield ÷ time
36 ÷ 28 = 1.29 g/s
Averaged over the whole shot, which includes any pre-infusion you counted.
Ranked guidance, not a diagnosis
How it works
Your numbers give the ratio and the flow rate. Those, your taste description and anything you saw at the basket are matched against a fixed set of rules, each of which carries a weight and an explanation. The rules are ranked, the strongest is presented as the next thing to try, and the rest are shown beneath it because espresso faults rarely have exactly one cause. Nothing here is a model that learned anything; every rule is written down and every result says which rules fired.
What the inputs mean
- Dose
- The dry coffee in the basket, weighed before brewing.
- Yield
- The mass of espresso in the cup, weighed. Not the volume.
- Shot time
- From the moment the pump starts to the moment you stop it. Whether to count pre-infusion is a convention; be consistent with yourself.
- Basket type
- Pressurised baskets have one small hole underneath and set the flow themselves. If you have one, grind changes will do very little, and this tool will say so first.
- Grinder adjustment
- Whether your grinder has fine steps near the espresso range. Some reach fine without adjusting finely within it, which is a different problem from being set wrong.
Worked examples
A fast, sour shot
- Dose 18 g
- Yield 40 g
- Time 15 s
- Tastes sour and thin
- Single-wall basket
Result: Grind finer, one or two steps, keeping dose and target yield the same. The shot is running at roughly 1:2.2 in half the usual time, so the bed is offering too little resistance.
A shot that sprays
- Dose 18 g
- Yield 36 g
- Time 22 s
- Tastes sour and harsh
- Spraying sideways
Result: Channelling first: stir the dose with a fine-needle tool and check the tamp is level. Grind is not the first thing to change here.
Common mistakes
Applying more than one suggestion at once
Two changes and a better shot tells you nothing about which one helped. The result names one thing to change for exactly this reason.
Treating a sour-and-harsh shot as a grind problem
Tasting under-extracted and over-extracted simultaneously is the signature of channelling. Grinding finer usually makes it worse.
Chasing a shot time
Time is a reading, not a target. A shot can hit twenty-eight seconds and taste bad, and a good shot can take longer.
What the result does not mean
- This is ranked guidance, not a diagnosis. Where several causes are plausible it says so rather than picking one.
- A suggestion that does not help is information: it rules a cause out. Work down the list.
- It cannot see your puck, your water or your machine's temperature stability, all of which affect the shot.
What this does not account for
- Assumes the coffee is reasonably fresh and the machine is clean. Very old coffee and a residue-caked group both produce faults this cannot see.
- Assumes you can weigh dose and yield. Without both, the ratio is unknown and the guidance is much weaker.
- Rules are ranked by how often each cause explains the symptom, not by any measurement of your specific setup.