Coffee Roast Level Chart: Cracks, Agtron and Brew Temperature

Roast level is how far a green coffee bean was taken along a heat curve, measured by colour and marked by two audible cracks. First crack, at around 196 to 205 C bean temperature, is where coffee becomes drinkable. Second crack, at around 224 to 230 C, is where oils reach the surface and roast flavour starts overwriting origin flavour. Everything a roast level tells you about brewing, grind, temperature and shelf life follows from where the roaster stopped between those two points.

What is the full roast level chart?

Agtron numbers below are the published colour classification bands rather than measurements of any particular bag, and roasters differ in whether they report whole bean or ground readings, so treat them as approximate. Bean temperatures are typical drop temperatures, not a rule: a slow roast and a fast roast can reach the same colour at different temperatures with very different results in the cup.

The 88 to 96 C spread across that brew temperature column is the single most useful thing on the page. Espresso brew temperature is conventionally quoted as 90 to 96 C, which is 194 to 205 F, and roast level is what tells you where inside that range to sit. Lighter and denser goes hotter, darker and more soluble goes cooler. A machine with PID temperature control lets you set that directly. A machine without one gives you a thermostat swing of several degrees, which is why single boiler machines reward a consistent flush and wait routine.

What actually happens at first and second crack?

First crack is the sound of steam and carbon dioxide bursting out of the bean's cell structure. Up to that point the bean has been drying and then browning through Maillard reactions, turning from green to yellow to tan. Pressure builds inside the cells until they give way, and the bean audibly pops and expands, roughly doubling in volume while losing 12 to 18% of its weight in water. Coffee dropped immediately after first crack is very light: acidic, cereal like, and often underdeveloped, meaning the inside of the bean is less roasted than the outside.

Between the cracks is where most of the interesting work happens. Sugars caramelise, acids break down, and body develops. The longer a roaster spends in this development phase, the more the perceived acidity drops and the sweeter and rounder the coffee becomes. Two coffees can drop at the same colour with very different development times and taste nothing alike, which is why colour alone is an incomplete description.

Second crack is the cell walls themselves fracturing as oils migrate outward. It is a quieter, sharper, more brittle sound. Past this point the roast character increasingly dominates whatever the origin brought, which is a deliberate choice rather than a fault: a dark roast blend for milk drinks is built to taste the same all year from beans that change with the harvest. Push far enough past second crack and you get carbon and ash, and the bean becomes structurally fragile enough to shatter into fines in the grinder.

How long should coffee rest after roasting?

Degassing is the release of carbon dioxide trapped during roasting, and it is the reason a roast date matters more than a best-before date. Too fresh and the gas physically disrupts the brew: espresso shots run fast and foam excessively, and pourover beds bloom so violently that the pour channels. Too old and the aromatics have gone and the oils have oxidised.

Espresso needs a longer rest than filter because it is the only brew method where gas actively fights the water. Nine bar of pressure through a compacted bed leaves the carbon dioxide nowhere to go, so it forms voids and channels. Filter brewing vents it harmlessly during the bloom. That is why the same bag can be excellent as a pourover on day four and unusable as espresso until day ten.

Storage decides how much of that window you keep. Keep beans whole, in an opaque, airtight container at room temperature, and never in the fridge, where condensation and odour absorption both work against you. A container with a plunger that expels the air, such as the AirScape canister , addresses the actual problem, which is oxygen rather than the lid. Buy in quantities you will finish in three to four weeks rather than in bulk.

How do you adjust your recipe when the roast level changes?

Every roast level change moves three dials in the same direction at once, which is why switching from a supermarket dark roast to a specialty light roast feels like the machine broke.

Change one at a time even so. Move the grind first, because it has the largest effect per step, and only reach for temperature if the grind alone cannot resolve sourness or bitterness. The brew ratio chart gives the dose and yield pairs for each ratio, the grind size chart shows how narrow the espresso window is, and the extraction troubleshooting chart covers what each fault tastes like when you get it wrong.

Which roast should you buy for your setup?

If the machine is new, start medium. A blend such as Lavazza Super Crema forgives a dose or grind error, produces thick crema and comes in a bag large enough to survive the shots you will waste while learning. Using an expensive single origin light roast to dial in a new machine is an expensive way to learn that both variables changed at once.

For a reference point that does not move, a sealed pressurised can such as illy Classico stays consistent far longer than a valve bag, which makes it useful as a control when you are trying to work out whether a problem is the coffee or the setup. For milk drinks specifically, a darker blend built for the job such as Peet's Espresso Forte cuts through milk in a way a delicate light roast simply will not.

When you are ready for specialty, buy from a roaster who prints a roast date rather than a best before date, such as Counter Culture Big Trouble . A roast date is the only piece of information on the bag that lets you use the rest table above. At that point the limiting factor is usually grind consistency, and the MiiCoffee DF64 II or another stepless grinder makes switching between bags practical rather than a chore. If the machine is next in line, a dual boiler with PID is what makes a temperature setting a number rather than an aspiration.

For the shot-by-shot sequence when a new bag arrives, the dial-in guide covers the first three shots, and the grinder roundup covers what each price band buys in particle consistency, which is what light roasts expose most cruelly.