How to Dial In a New Bag of Coffee

You bought a new bag of beans. The label has a tasting note that says something like “caramel, stone fruit, dark chocolate” and you would like any one of those flavors to show up in your cup. Right now the shot tastes like a lemon had an argument with a puddle.

This is normal. Every new bag needs dialing in, which is the process of adjusting your recipe until the espresso tastes balanced. It is not a talent. It is a method. The method is slow, a little wasteful, and it works.

The short answer

Start with a fixed dose, pull a shot, taste it, and adjust grind size first. One change at a time. Write it down or remember it, but do not change two things between shots. Sour means under-extracted: grind finer. Bitter means over-extracted: grind coarser. Three to six shots usually gets you there.

Why every bag is different

Coffee beans vary by origin, variety, processing method, roast level and age since roasting. A medium-roast Colombian and a light-roast Ethiopian are as different as two entirely separate ingredients, and your grinder does not know that. The setting that gave you a beautiful shot from last week’s bag may give you a gushing, sour mess with this week’s.

Dark roasts tend to extract more easily. They are more soluble and more brittle, so they grind finer at the same setting and produce faster shots [1]. Light roasts are denser and harder, resist extraction and often need a finer grind to get the same contact time. None of this is a problem. It just means the grinder setting is not a permanent answer. It is a starting point that moves.

The age of the beans matters too. Most roasters recommend resting beans for at least five to seven days after roasting before using them for espresso. Very fresh beans still contain a lot of carbon dioxide, which creates bubbles in the coffee bed and makes extraction uneven. Beans at seven days behave differently from beans at twenty-one days, even from the same bag, so small adjustments over the life of the bag are part of the process, not a sign of a problem [2].

What you need before you start

• A scale that reads to at least 1 gram, ideally 0.1 grams.
• Your grinder, set to roughly where it was with the last bag.
• A timer (most machines have one, or use your phone).
• A notebook, a phone note, or a very good memory.
• At least 100 grams of beans to spare. Dialing in costs beans. Budget for it.

The method, step by step

1. Set a fixed dose

Pick a dose and do not change it during the dialing-in process. For a standard double portafilter, 18 grams is a common starting point. If your basket is larger or smaller, check the manufacturer’s recommended range. Weigh the dose. Eyeballing it introduces a variable you cannot track.

2. Set a target ratio and time

A 1:2 ratio in 25 to 30 seconds is a sensible starting point for most medium roasts. That means 18 grams of ground coffee in, 36 grams of liquid espresso out, in 25 to 30 seconds from the moment the pump starts [2]. This is not a rule. It is a starting coordinate.

For lighter roasts, some people aim for a longer ratio (1:2.5 or even 1:3) because the extra water helps extract more of the flavor from the denser beans. For darker roasts, a shorter ratio (1:1.5 to 1:2) can keep the shot from tasting hollow. But start at 1:2 regardless. You need a baseline before you start moving.

3. Pull the first shot

Grind, tamp evenly (firm and level, do not overthink the pressure), and pull the shot. Time it from when the pump starts. Weigh the output. Taste it. Write down the grind setting, the dose, the yield, the time and what it tasted like.

This shot will probably not be good. That is the point.

4. Read the shot

Here is the simplest diagnostic:

• Sour, thin, watery, fast: under-extracted. The water moved through too quickly and grabbed the bright acids but missed the sugars and body. Grind finer.
• Bitter, heavy, dry, ashy, slow: over-extracted. The water sat in the coffee too long and pulled out harsh compounds from the tail end of extraction. Grind coarser.
• Both sour and bitter at the same time: this usually means channeling. The water found paths of least resistance through the coffee bed and over-extracted those channels while under-extracting the rest. Check your distribution and tamp. Make sure the bed is even before tamping.

5. Adjust grind size only

One variable: grind size. Everything else stays put.

Move the grinder one to two clicks in the direction the taste told you. Pull another shot with the same dose, aiming for the same yield. Time it. Taste it. Write it down.

If the shot is still sour, go finer again. If it crossed into bitter territory, back up one click. You are looking for the spot where the sourness has gone and the bitterness has not arrived. That middle ground is where the sweetness, body and flavor notes live [1].

6. Repeat until balanced

Most bags land in three to six shots. Occasionally a bean is stubborn and takes more, especially if it is a very light roast or a natural process with an unusual flavor profile. That is not your fault. Some beans are harder to extract evenly.

Once the shot tastes balanced at a 1:2 ratio, you can experiment. Try a slightly longer or shorter ratio. Try a degree or two of temperature if your machine allows it. But those are refinements. Grind size does most of the work.

A shot log

This shot log is fictional and illustrative.

New bag: medium-roast blend from a local roaster, seven days off roast. Machine: a prosumer single boiler. Grinder: a mid-range flat burr.

Dose	Yield	Time	Taste	Next move
18 g	40 g	18 s	Sour, thin, fast, no body	Grind three steps finer
18 g	37 g	24 s	Less sour, some sweetness starting, still a bit sharp	Grind one step finer
18 g	36 g	27 s	Balanced, sweet, light chocolate, medium body	Keep this setting

Three shots. Two down the sink, one in the cup. That is a normal dialing-in session.

Common mistakes

Changing two things at once. You grind finer and also increase the dose. The shot improves. Which change helped? You do not know, and next time you will not know which one to adjust. Change one thing. Taste. Then decide.

Skipping the scale. “About 18 grams” can be 16 or 20 depending on how generous the scoop was. A gram of difference in dose changes the shot noticeably. Weigh it.

Giving up after one bad shot. The first shot from a new bag is almost always wrong. That is the starting data, not the final product. The method is designed to start wrong and get right.

Not resting the beans. If the bag arrived today and you are pulling shots tonight, the beans are probably too fresh. CO2 is still escaping, the shots will be bubbly and uneven, and no amount of grind adjustment will fully compensate. Give it a few days [2].

Blaming the machine. The machine is almost never the problem when you switch bags. The grinder and the beans are doing the work. If the machine pulled a good shot last week, it can pull one this week. The recipe just needs updating.

When grind size is not enough

Sometimes you chase the grind through every click and the shot still tastes off. A few things to check:

1. Bean freshness. If there is no roast date on the bag, or the roast date is more than five or six weeks ago, the beans may be stale. Stale beans produce flat, papery shots that no grind adjustment will fix. Buy beans with a roast date and try to use them within three to four weeks of that date.
2. Distribution and tamp. If the coffee bed is uneven before tamping, water will channel through the thin spots. A few taps on the side of the portafilter, a quick stir with a thin needle (WDT technique), or a leveling tool can help distribute the grounds more evenly.
3. Water. Very soft or very hard water changes extraction. The SCA recommends water with a total dissolved solids (TDS) range of roughly 75 to 250 mg/L for brewing [5]. If your tap water is outside that range, it may be affecting taste. This is the boring variable chapter, and it has its own post.
4. Temperature. If your machine allows temperature adjustment, try raising it by 2 to 3 degrees Fahrenheit for light roasts (which need more energy to extract) or lowering it for dark roasts. But only after grind size and bean freshness are sorted.

The upgrade ladder for dialing in

If you want to dial in more easily and consistently, here is where to spend, in order:

1. A scale (if you do not have one). Under $20 for a basic 0.1 g kitchen scale.
2. Fresh beans from a roaster with a date on the bag. This is not an upgrade you buy once. It is a habit.
3. A better grinder. A grinder with smaller, more consistent steps makes it easier to find the sweet spot instead of jumping over it. This is the single most impactful equipment upgrade for espresso quality.
4. A distribution tool or WDT needle. Cheap, helps with even extraction, reduces channeling.
5. A machine with temperature control. Useful for light roasts and for dialing in by temperature, but only after the grinder is sorted.

Caffeine, heat and your machine. The FDA says up to about 400 mg of caffeine a day is not generally associated with negative effects for most healthy adults; pregnancy, some heart conditions, anxiety, reflux and certain medicines can change that, so check with a clinician if any apply. Steam wands and group heads are hot enough to burn. Unplug and cool a machine before opening or cleaning it, and follow the manufacturer’s descaling instructions.

Related reading: Why Is My Espresso Sour? | Best Espresso Grinder for Every Budget