Independent brewing lab — not affiliated with PourX, Abilliant or the domain's previous owner.
pourxlabthe pour-over lab

Guide · home roasting

How to roast coffee at home: stages, temperatures and safety

To roast coffee at home, heat green beans while keeping them moving until they dry, turn yellow and brown, and reach first crack at about 196 °C (385 °F); stop anywhere from the end of first crack to the start of second crack at about 224 °C (435 °F), cool the beans in minutes, and let them rest before brewing. Expect the beans to lose about 9–20% of their weight, more the darker the roast, and to deal with chaff and smoke.

The stage chart below sets those temperatures beside a timed example roast, two lab studies and the SCA's sample-roasting rules; the safety section summarizes US fire and health agency advice.

Updated 2026-11-14 · sources listed at the end

Coffee roasting stages chart: temperature, time and cues

Temperatures are given as each source states them: Wikipedia's approximate bean temperatures, and the probe readings of one timed example roast published by Sweet Maria's, a green-coffee seller. Sweet Maria's itself says to take its temperatures "as a ballpark figure" and to ignore the times, because readings depend on the roaster and where the probe sits, so read the two columns as a range, not a target.

StageTemperatureTime in the example roastWhat you see, hear and smell; what is happening
1. DryingWikipedia: drying phase at 165 °C (329 °F)0:00–6:00 (75 → 327 °F); little change in the first few minutesSteam and a humid, hay-like smell. The beans take in heat (endothermic). Kim and colleagues (2021) describe this dehydration phase as the one where "most of the water is steeply lost".
2. Yellowing and browningWikipedia: turns exothermic at about 175 °C (347 °F)6:00–9:20 (327 → 401 °F)Yellow, then tan and light brown, with toasty, bread-like smells (Sweet Maria's); "bread or burlap" (Coffee Review). Brown pigments build up as caramelization and the Maillard reaction progress (Kim et al.). Chaff starts to come off at about 370 °F.
3. First crackWikipedia: about 196 °C (385 °F); example roast 401 °F at onset9:20–10:40; 2–5 min in a hot-air popperLoud popping, like popcorn; the beans visibly expand. First crack finishing at 426 °F is City roast, which Sweet Maria's treats as the earliest stopping point worth drinking; CO2 starts to come off.
4. DevelopmentExample roast: City+ 435 °F, Full City 444 °F10:40–11:50; the gap before second crack can be 15–30 sLindsey and colleagues (2024) define development as the time from the onset of first crack to the end of the roast, and stopped their roasts 0, 1, 3, 5 or 7 minutes after it. Popping trails off; the smoke darkens and smells sweeter (Coffee Review). Roast levels are covered on the roast levels chart.
5. Second crackWikipedia: about 224 °C (435 °F); example roast ≈446 °F, first snaps 454 °F11:50–12:40 (Vienna to light French at 465 °F)A quieter crackle, "more like paper being crinkled" (Coffee Review), with more smoke just before it. Origin character gives way to roast character.
6. Past second crackExample roast: 474 °F full French; 486 °F carbonized; 497 °F imminent fire12:40–13:30Ashy, burnt flavors and thick, pungent smoke. Sweet Maria's warns that beans this hot can catch fire, especially once they are dumped into the cooling tray.

The two cracks also differ in sound. In Preston Wilson's 2014 acoustics study (reported by Daily Coffee News), first crack was about 15% louder in peak acoustic pressure, nearly 19 times lower in frequency, and its cracks came at about one fifth the rate of second-crack cracks. That is why listening is the main cue in home roasting.

How long should a roast take? The SCA requires cupping samples to be roasted in no less than 8 and no more than 12 minutes. Sweet Maria's says popcorn-popper roasts last anywhere from 6 to 15 minutes, and its example roast reached second crack just before the 12-minute mark.

The example roast as a curve

Example home roast curve: bean-probe temperature against time, with roasting stagesA line chart of temperature in degrees Fahrenheit (50 to 500) against roast time in minutes (0 to 14). The line follows the example roast published by Sweet Maria's, rising from 75 degrees at the start to 401 degrees at first crack at 9 minutes 20 seconds, 454 degrees at the first snaps of second crack at 11 minutes 50 seconds and 497 degrees, imminent fire, at 13 minutes 30 seconds. Shaded bands mark six stages: drying, yellowing and browning, first crack, between the cracks, second crack, and carbonizing with fire risk. Dashed horizontal lines mark the approximate temperatures Wikipedia gives for the exothermic turn (347 F), first crack (385 F) and second crack (435 F). Numbered markers 1 to 9 match the list below.10020030040050002468101214roast time, minutes (one example roast)probe temperature, °F789123456Example roast curve and stages
  1. Drying, 0:00 to 6:00: 75 °F at the start, 270 °F at 4:00, 327 °F at 6:00.
  2. Yellowing and browning, 6:00 to 9:20: 345 °F at 6:30, 370 °F at 8:00, 393 °F at 9:00.
  3. First crack, 9:20 (401 °F) to 10:40 (426 °F, City); 415 °F at 10:00.
  4. Between the cracks: City+ 435 °F at 11:05, Full City 444 °F at 11:30.
  5. Second crack: first snaps at 454 °F at 11:50, Vienna to light French 465 °F at 12:15.
  6. Past second crack: full French 474 °F at 12:40, carbonized 486 °F at 13:00, imminent fire 497 °F at 13:30.
  7. Exothermic turn, about 175 °C (347 °F), Wikipedia.
  8. First crack, about 196 °C (385 °F), Wikipedia.
  9. Second crack, about 224 °C (435 °F), Wikipedia.
Drawn by pourxlab.com for this page. The line plots the times and probe temperatures of the example roast in Sweet Maria's "Using Sight to Determine Degree of Roast" (source 7); dashed lines are the approximate bean temperatures in Wikipedia's coffee roasting article (source 1). One roast on one machine, illustrative: probe readings and times differ between roasters, which is why the example's first crack (401 °F) sits above Wikipedia's 385 °F line.

Roast loss: how much weight beans lose

Beans lose water, CO2 and volatile compounds as they roast, so a roasted batch weighs less than the green coffee that went in. How much depends on how far the roast goes:

SourceRoastMass loss
Lindsey et al. 2024 (washed Ethiopian, 500 g drum batches)Dropped at the onset of first crack / 1 min later8.9% / 11.6%
Kim et al. 2021 (Ethiopian heirloom)Light-medium and medium12%
Kim et al. 2021Moderately dark / very dark16% / 20%
Wikipedia, Coffee roastingRoasting in general15–18%

Lindsey's team found natural-process batches lost consistently 2–3 percentage points more than washed ones (processing methods), and Kim's group measured moisture falling from 8.64 g per 100 g in the green beans to 2.56 g at light-medium and 0.89 g at very dark. Meanwhile volume roughly doubles, Wikipedia notes. To track it yourself, weigh the green charge and the cooled roast on a kitchen scale: loss % = (green − roasted) ÷ green × 100. At 15% loss, for example, 100 g of green coffee gives 85 g roasted.

Methods and batch size

  • Purpose-made fluid-bed (hot-air) roasters heat beans faster, keeping more acidity but making a harder bean; typical batches are 4–8 oz (110–230 g), Wikipedia says, and some counter-top models run their own cooling cycle.
  • Drum roasters take somewhat larger batches and more time, giving a softer bean with less evident acidity.
  • Oven: one layer of beans on a perforated tray with raised sides; beans at the edge darken first, and "a lot of smoke will be generated".
  • Skillet, wok or stovetop popcorn maker: constant stirring or cranking and plenty of ventilation.
  • Hot-air popcorn popper: Wikipedia calls it a light-duty appliance "not designed to withstand the longer heat cycle" that may fail from heat damage, and Sweet Maria's notes that roasting coffee in one voids its warranty. Its tip sheet suggests ⅓ to ½ cup of beans.

Chaff and smoke

Chaff is the paper-thin skin that flakes off during roasting. Coffee Review says home roasting machines keep it from floating around the kitchen, but open methods scatter it, and Sweet Maria's warns that chaff falling onto a popper's workspace can be drawn into its vents and burn. Smoke ranges "from faint wisps" at a light roast "to black and cloying clouds" at a dark one, and Coffee Review adds that no home machine fully contains it: roast under a kitchen exhaust fan or outdoors on a patio. Indoors, Wikipedia notes, a room can keep a smoky smell long afterward.

Fire and carbon monoxide safety

The fire and health agencies cited here give general cooking and carbon monoxide advice rather than rules for coffee roasting; the points below summarize it. Follow your roaster's manual first.

  • Stay with it. Cooking is "by far, the leading cause of home fires and home fire injuries", says the U.S. Fire Administration (USFA): "Stand by your pan. If you leave the kitchen, turn the burner off." Sweet Maria's says the same for roasting: "Don't step away", because "the difference between a dark roast and a fire can be just a few moments".
  • Clear the area. Keep anything that can catch fire away from the heat, and clean equipment after each use so residue cannot ignite (USFA); Sweet Maria's notes that chaff left inside a popper can eventually burn.
  • Know the fire response. For a pan fire, the USFA says to cover the pan with a lid or baking sheet kept nearby; for an oven fire, turn it off, and if flames escape the oven, leave and call 911.
  • Extinguisher: use one only when the fire is small and contained to a single object and you have a clear escape route; otherwise alert others, get out and call 911. The USFA's steps are Pull, Aim low, Squeeze, Sweep.
  • Carbon monoxide: CO is produced "any time you burn fuel" (CDC). Never burn charcoal or use a portable gas camp stove indoors, and the CPSC adds garages, tents and campers to the list. Install battery-operated or battery back-up CO detectors near every sleeping area.
  • Handle hot gear with oven mitts (Sweet Maria's).

Cooling the beans

Cool the beans as soon as the roast ends. The SCA's cupping protocol says samples should be "immediately air-cooled (no water quenching)". At home, Wikipedia describes shaking or tossing the beans in a metal colander for a few minutes, and Sweet Maria's tip sheet pours them into a metal colander or another heat-conducting container and stirs until they cool.

Resting after roasting

Fresh roasts hold carbon dioxide. Smrke and colleagues (2018) put it at 1–2% of the weight of freshly roasted coffee, found darker and longer roasts form more gas, and measured light-roasted whole beans still degassing a month after roasting; grinding fresh coffee released up to 75% of the trapped gas within 90 seconds. That gas is what makes a fresh roast bloom. How long to wait before brewing varies by source:

SourceRest before brewing
SCA cupping protocolAt least 8 hours, cupped within 24 hours of roasting
Sweet Maria's popper tip sheetAbout a day
Lindsey et al. 2024 (lab method)10 days of degassing before grinding
Wikipedia, Home roasting coffeeFlavor peaks 7–14 days after roasting; some coffees up to 21 days

Store the cooled beans airtight: Sweet Maria's suggests a mason jar or a tin or bag with a one-way valve, and the SCA keeps cupping samples in a cool, dark place, not refrigerated or frozen. More on containers is in how to store coffee beans and on staling in coffee freshness.

Buying and keeping green coffee

Green coffee keeps far longer than roasted. Wikipedia's home-roasting article gives 1–3 years depending on storage, while noting that some home roasters cut that to 8 or even 1.5 months. When fresh-crop green coffee from each origin reaches the US is on the coffee harvest calendar.

Checklist: a first home roast

  • Ventilation ready: exhaust fan on or roaster outdoors; nothing that can burn nearby; lid or baking sheet and extinguisher within reach.
  • Weigh the green coffee and keep the batch within the roaster's stated size.
  • Stay with the roast from start to finish; listen for first crack.
  • Decide the stop point: after first crack ends for lighter, before or at the first snaps of second crack for darker.
  • Dump into a metal colander and stir until cool; collect or sweep up the chaff.
  • Weigh again and note the loss %; label the jar with the roast date.
  • Rest at least 8 hours, then taste across the following days and write it in your brew log.

Temperatures and times in this guide come from the cited sources and one example roast; your roaster, probe and beans will differ. Roast by sound, color and smell, and never leave a roast unattended.

Sources

  1. Wikipedia — Coffee roasting (secondary: drying phase 165 °C, exothermic from about 175 °C, first crack about 196 °C, second crack about 224 °C, 15–18% mass loss, volume roughly doubles)
  2. Wikipedia — Home roasting coffee (secondary: methods, 4–8 oz batches, ventilation, colander cooling, hot-air popper caution, rest and green-coffee storage)
  3. Kim I., Jung S., Kim E., Lee J.-W., Kim C.-Y., Ha J.-H., Jeong Y. (2021) Physicochemical characteristics of Ethiopian Coffea arabica cv. Heirloom coffee extracts with various roasting conditions. Food Science and Biotechnology 30(2):235–244 (PMC)
  4. Smrke S., Wellinger M., Suzuki T., Balsiger F., Opitz S.E.W., Yeretzian C. (2018) Time-resolved gravimetric method to assess degassing of roasted coffee. Journal of Agricultural and Food Chemistry 66:5293–5300 (ZHAW repository)
  5. Lindsey Z.R., Williams J.R., Burgess J.S., Moore N.T., Splichal P.M. (2024) Caffeine content in filter coffee brews as a function of degree of roast and extraction yield. Scientific Reports 14:29126 (copy hosted by the University of Oregon)
  6. Specialty Coffee Association — Protocols & Best Practices (cupping sample roast: 8–12 minutes, immediately air-cooled, rest at least 8 hours, airtight storage)
  7. Sweet Maria's Coffee Library (a green-coffee seller) — Using Sight to Determine Degree of Roast (timed example roast; temperatures "a ballpark figure")
  8. Sweet Maria's — Hot air popper tip sheet (PDF: 6–15 minute roasts, first crack at 2–5 minutes, chaff, stay with the roast, colander cooling, rest about a day)
  9. Coffee Review — Home Coffee Roasting: The Listening-to-the-Beans Approach
  10. Coffee Review — Home Coffee Roasting: Home Roasting Annoyances and Precautions (chaff, smoke, exhaust fan or outdoors)
  11. Daily Coffee News (2014) — A quantitative description of the sounds of cracks during roasting (Preston Wilson, Journal of the Acoustical Society of America 135(6))
  12. U.S. Fire Administration — Cooking fire safety
  13. U.S. Fire Administration — Cooking fire safety flyer (PDF: oven fires)
  14. U.S. Fire Administration — Choosing and using fire extinguishers
  15. CDC — Carbon monoxide (CO) poisoning basics
  16. U.S. Consumer Product Safety Commission — Charcoal (carbon monoxide)