How to Learn Coffee Roasting Before You Buy: Courses, Certification and Practice
How to learn coffee roasting comes down to three things, done in order. Learn the theory. Cup a lot of coffee. Then log real roasts on a machine close to...
Looking for the best commercial coffee roasting machine for your business? Start with capacity. The roaster you pick sets your daily output and your flavor control. It also decides how far you can grow before you need a bigger machine. Brand and fuel type come next.
This guide compares 10 proven roasters from six brands, from a 5 kg Diedrich to a 90 kg Probat. You'll also see where a commercial roaster ends and an industrial coffee roaster begins. Then we cover how much coffee each size really produces per hour and what to check on a used machine. Opening a café or buying your first roaster? Our best coffee roaster machines for small business guide covers 1 to 10 kg entry machines in more depth. This page focuses on mid to large production roasters.
Here's how all 10 roasters line up on capacity, fuel, and fit. Use it to shortlist two or three, then read the detail below.
| Model | Batch Capacity | Fuel | Standout Features | Best For |
|---|---|---|---|---|
| Probat G75 | Up to 75 kg | Natural gas | Cyclone, destoner, manual controls | Industrial production |
| Probat G90 | Up to 90 kg | Natural gas | Heavy-duty drum, exhaust and motors | Continuous wholesale schedules |
| Diedrich IR-5 | 250 g to 5 kg | Natural gas or propane | Infrared burners, stainless cooling tray | Small specialty roasteries |
| Diedrich IR-12 | 6 to 12 kg | Natural gas or propane | USB data port, automation options | Growing wholesale roasters |
| US Roasters Revelation | Up to 70 kg | Propane | Destoner, vacuum loader, adjustable drum speed | High-volume production |
| US Roaster Corp 35 kg | Up to 35 kg | Natural gas | Chaff collector, water-quench cooler | Roasteries outgrowing a 12 to 15 kg drum |
| Mill City MCR-10 | Up to 10 kg | Natural gas | Data logging, adjustable fan and drum speed | Specialty brands scaling up |
| Mill City MCR-20 | Up to 20 kg | Propane | Roasts and cools at the same time | Single-operator production |
| Coffee-Tech Ghibli R-15 | 3 to 15 kg | Gas or wood-fired | External cooling, cyclone, destoner | Medium-volume production |
| Giesen W6A | Up to 6 kg | Natural gas | Separate roast and cooling motors | Craft roasters adding volume |
The difference is mostly batch size and how many hours a day the machine runs. A commercial coffee roaster handles roughly 5 to 30 kg per batch and runs a shift or two. An industrial coffee roaster starts around 30 to 60 kg and is built to run all day.
There's no single official cutoff. Probat, which has built roasters since 1868, uses a clean rule in its own engineering literature. A roaster counts as industrial once the drum holds 60 kg, one full sack of green coffee, according to this overview of how roasteries are classified. CoffeeTec draws the line a little lower and lists 30 kg and up in its used industrial coffee roasters collection.
By either rule, four machines on this list are industrial: the Probat G75, the Probat G90, the 70 kg US Roasters Revelation, and the 35 kg US Roaster Corp. Here's what changes once you cross that line:
Here's where all 10 roasters on this list fall on that scale.

A reliable brand protects your investment. Established makers have parts in circulation, service techs who know the machines, and a resale market that holds value. Here are 10 roasters worth a close look.
Probat has built roasters in Germany since 1868. Its G series is the classic large-batch drum line. CoffeeTec's catalog has carried more than 200 Probat roaster listings, from 100 g sample roasters to full roasting plants.

The 75 kg Probat G75 is built for industrial-scale roasting. It comes with a destoner and cyclone, manual controls, and wiring for both 50 Hz and 60 Hz systems. Rebuilt G75s turn up on the used market regularly, so watch the used Probat roasters collection for the next one.
Important Features:

The 90 kg Probat G90 steps up the motors across the drum and exhaust for longer production runs. Some G90s still roasting today were built in the 1950s and 1960s, which tells you how these drums hold up with care. CoffeeTec currently lists a 1968 Probat G90 sold as a full mini plant.
Important Features:
Diedrich's infrared burners heat the drum evenly and respond fast to burner changes. That's why specialty roasters keep coming back to the brand, and it's one of the most traded roaster lines on CoffeeTec. Browse every size in the Diedrich coffee roasters collection.

The IR-5 gives a small roasting business commercial-grade control in a compact footprint. It handles batches from 250 grams up to 5 kg with repeatable results. See this 2017 Diedrich IR-5 in excellent condition.
Important Features:

If one machine defines the used commercial roaster market, it's the IR-12. CoffeeTec's catalog holds more than 80 IR-12 listings, current and past, from 1980s units to fully automated models still in the crate. It handles up to 12 kg (about 26 lb) per batch, a natural next step after a shop roaster. One current example is this Diedrich IR-12A automatic roaster.
Important Features:
US Roaster Corp has built roasters in Oklahoma City for over 40 years. Its machines are known for heavy steel, double-insulated housings, and straightforward controls.

The 70 kg Revelation is a true industrial production roaster, running up to 4 dark roasts per hour. Its destoner and vacuum loader keep a busy line moving. CoffeeTec currently lists this 2016 US Roasters Revelation in excellent condition.
Important Features:

The 35 kg model runs on 220V three-phase power and pairs with Cropster or Artisan. It's simple to operate and a good fit for a roastery moving past its first 12 or 15 kg drum. See current models in the US Roaster Corp collection.
Important Features:
Mill City builds small to medium commercial drums with clear, user-friendly controls. Its machines are popular with specialty brands that want data logging without a steep learning curve.

The MCR-10 gives you hands-on control of gas, fan, and drum speed, plus logging that suits a growing specialty brand. MCR-10s move quickly on the used market, so check the Mill City roaster collection for current listings.
Important Features:

The MCR-20 roasts and cools at the same time, and its high-pressure blower keeps exhaust clean. One operator can run it comfortably. For other machines in this size class, browse large batch roasters, 20 kg and up.
Important Features:
Coffee-Tech builds batch drum roasters in Israel, and its Ghibli series targets precise control at medium volume. See the full lineup of Coffee-Tech roasters.

The Ghibli R-15 roasts 3 to 15 kg per batch with external cooling, for up to 60 kg per hour. Most units are gas-fired, and wood-fired versions exist too. CoffeeTec currently lists a 2022 wood-fired Ghibli R-15.
Important Features:
Giesen is a Dutch maker that gives craft roasters fine control at commercial output. Its dual-motor design roasts and cools at once. That's why the brand shows up next to Probat and Diedrich in so many buyer comparisons. Browse current Giesen coffee roasters.

The W6A roasts up to 6 kg per batch and cools the last batch while the next one roasts. That cuts turnaround time without hurting consistency. It's a strong pick for a roastery moving up from a shop machine but not ready for a 20 kg drum. See this 2017 Giesen W6A in excellent condition.
Important Features:
Less than the number on the data plate. Plan on 3 batches an hour at 50 to 80 percent of rated capacity. Then subtract about 15 to 20 percent for moisture lost during the roast.
Roast consultant Anne Cooper treats 25 percent of drum size as a practical minimum batch and 80 percent as a practical maximum. That's according to Roast Magazine. Full-drum batches roast slower and give you less control.
Here's what that looks like for three common sizes:
| Rated Batch Size | Practical Batch (70%) | Green Coffee per Hour (3 batches) | Roasted Coffee per Hour (about 17% loss) |
|---|---|---|---|
| 5 kg (Diedrich IR-5) | 3.5 kg | 10.5 kg | About 8.7 kg (19 lb) |
| 12 kg (Diedrich IR-12) | 8.4 kg | 25.2 kg | About 21 kg (46 lb) |
| 35 kg (US Roaster Corp) | 24.5 kg | 73.5 kg | About 61 kg (134 lb) |
Now work backward from demand. If you sell 400 lb of roasted coffee a week, a 12 kg roaster covers it in under 9 roasting hours. That leaves room to grow. A 5 kg machine would need more than 20 hours for the same volume. That's usually when roasters start shopping for the next size up.
Want to run your own numbers? Enter your weekly volume and the hours you can roast, and the planner shows which batch size fits.
Roaster size planner
Which Batch Size Fits Your Weekly Volume?
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| Roasters in this guide that fit | Max batch | Hours a week for your volume |
|---|
How we calculate: 3 batches per hour, each loaded at 70 percent of the rated batch size, and about 17 percent weight lost during the roast. These are planning rules of thumb, so real output varies with roast level and machine.
The roaster type shapes flavor, consistency, and capacity as much as the brand does. These are the four you'll see most.
Drum roasters are the commercial standard. A rotating drum tumbles the beans over a gas or electric heat source, so you get tight control of temperature and time. Every machine on this list is a drum roaster. They produce rich, balanced coffee at large batch sizes and need regular cleaning to stay that way.

Fluid bed roasters lift the beans on a column of hot air. They roast faster and evenly, and they suit lighter roasts that show off a coffee's acidity. They're less common at very large batch sizes.
Hybrids combine a drum with forced hot air. You get even heat from the drum and faster roasting from the airflow. Hybrids work well for medium to dark roasts at medium to large volume.
Electric roasters run clean indoors and skip the gas line, so they fit sites where gas isn't an option. They're common at small to medium batch sizes. Our commercial electric coffee roaster guide covers power requirements and the leading electric models.

The right roaster protects your production schedule. Here's what to weigh, in the order that saves the most time.
Use the output math above. Size to your busiest week plus room to grow. Too small, and you're roasting late every night. Too big, and small batches roast poorly and waste fuel.
Pick drum for body and fine control. Pick fluid bed for speed and bright, light profiles. Let the roast style your customers buy decide this one.
Gas gives fast heat response on large batches. Electric is simpler to install. Either way, confirm voltage, phase, and gas supply at your site before you commit to a machine.
New roasters come with a factory warranty and the latest controls. A used roaster from the same brand costs less up front and has a proven track record. Every roaster listing on CoffeeTec shows the year built, condition, location, last used date, and last service date. That makes side-by-side comparison easy. Inspect the drum, burners, bearings, and motors for wear. Then test every control, sensor, and safety cutoff before it ships.
Look for open access to the drum, cooling tray, and chaff collector. A roaster that's easy to clean stays in service longer and roasts more consistently.
Logging tracks every profile, and automation repeats it. Both matter more once you run multiple batches a day for wholesale accounts. New to roasting? Our best coffee roaster machines for beginners guide explains which controls are worth having on day one.
Price follows capacity, brand, age, and automation level, and a used machine from the same brand often costs far less than new. Installation, venting, and support equipment add to the total. For a full breakdown by size and condition, see our coffee roasting machine cost guide.
It can be, when the roaster fits the business. Roasting in-house gives you control over cost and quality, and that builds loyal wholesale and retail customers. Margins depend on green coffee sourcing, energy use, and how full you keep the roaster's schedule. A machine sized to your real demand is the first step.
Many buyers on this page already own a roaster. Moving from a 5 kg to a 12 kg, or from a 15 kg to a 35 kg? Your current machine is exactly what another roaster is looking for. [CoffeeTec team: add the upgrade path sellers list most often, for example IR-5 to IR-12, from recent listings.] CoffeeTec has served the coffee industry since 1972. You can list your used roaster for sale to buyers searching this exact category. Our guide to selling a used coffee roaster walks through photos, specs, and timing. Prefer a new machine for your upgrade? Browse current new commercial coffee roasters.

The best machine is the one sized to your output. For small specialty roasteries, the Diedrich IR-5 and Giesen W6A are proven picks. For growing wholesale, the Diedrich IR-12 and Mill City MCR-20 are common choices. For industrial production, look at the Probat G75 or G90 and the US Roasters Revelation.
Capacity and duty cycle. Commercial roasters handle roughly 5 to 30 kg per batch for a shift or two a day. Industrial roasters start around 30 to 60 kg and run all day, often with loaders, destoners, and silos. Probat sets its industrial threshold at 60 kg, one green coffee sack.
Take your weekly roasted coffee volume and divide by the realistic hourly output of each size. Aim for a machine that covers your busiest week in about 20 to 25 roasting hours, so you have room to grow.
Most drum roasters run 3 to 4 batches per hour. Machines that roast and cool at the same time keep that pace more easily. On a Giesen W6A or Mill City MCR-20, the next batch starts while the last one cools.
Gas responds faster and is standard on large drums. Electric needs no gas line and runs clean indoors, which suits smaller commercial sites. Your utilities and batch size usually decide it.
New gives you a factory warranty and the latest controls. Used gives you a proven machine from the same brands at a lower upfront cost. With a used roaster, check the year built, service history, and condition of the drum, burners, and motors.
Cost depends on capacity, brand, age, and automation. Installation, venting, and support equipment like destoners and afterburners add to the total. The cost guide linked above breaks it down by size and condition.
With routine cleaning and service, decades. CoffeeTec currently lists a Probat G90 built in 1968 that's still in excellent working condition.
Drum roasters are the commercial standard, with fuller body and more control at large batch sizes. Air roasters roast faster and give a brighter, cleaner cup, usually in smaller batches.
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