What size coffee roaster do I need?

Work back from your target weekly volume in two to three years, roast loss and the hours you want to roast, then allow headroom. Many growing roasteries buy one size larger than they need today.

Is a 5 kg roaster enough to start?

For many new roasteries, yes. It can produce well over 100 kg of roasted coffee a week in a few hours of roasting. Plan for what happens when you outgrow it.

Should I buy a sample roaster too?

If you buy green coffee from samples or develop profiles, a sample roaster saves production batches and green. See the guide on samples and sample roasting.

Choosing a coffee roaster: batch size, fuel and design

Size the roaster from the volume you expect in year two or three, not from what you sell today, then let fuel, site and support narrow the field. A buyer's framework, not a brand list.

9 min read Updated October 9, 2026

A roaster is the largest purchase most roasteries make, and the one that is hardest to change. Choose it from your sales forecast, your site and the support you can get, in that order. Looks and reputation come after.

1. Size it from kilos per week

Start with the roasted kilos per week you expect in two to three years. Add roast loss to get green kilos. Then decide how many hours a week you want to spend roasting. Divide, and you have the green kilos per hour you need.

Worked example, assumed figures
Step	Result
Target roasted volume in year three	400 kg a week
Green needed at 16% roast loss	400 / 0.84 = about 476 kg
Hours you are willing to roast	12 hours a week
Green per hour needed	about 40 kg an hour
At four batches an hour	about 10 kg green per batch
Working at about 80% of nameplate	a roaster rated at roughly 12 kg to 15 kg

The same arithmetic with 200 kg a week and 10 hours points to a smaller machine, and with 1,000 kg a week to a much larger one or a second roaster. See batch scheduling for throughput.

2. Fuel and power

Natural gas, LPG and electric roasters each suit different sites. Gas offers fast heat response and is common on production machines; electric roasters are simpler to install where gas is not available, but need a large electrical supply at bigger sizes. See gas vs electric roasters.

3. Heat transfer design

Design	How it heats	Points to consider
Conventional drum	Burner under or around a solid or perforated drum; mix of conduction and convection	The most common design; wide range of sizes and second-hand availability
Indirect or semi-hot-air drum	Heat source separate from the drum; mostly hot air through the drum	More convective; often good airflow control
Hot-air recirculation	Hot air recirculated through the drum, often with integrated smoke burn-off	Can be more fuel-efficient; usually a higher purchase price
Fluid bed	Beans suspended in a stream of hot air	Fast and even; very different profiles from a drum, compact

There is no best design; each gives different control and flavor tendencies. Roast on the machines you are considering, ideally with your own coffees, before deciding.

4. Controls and data

Accurate bean temperature and exhaust temperature probes, placed where they read consistently
Adjustable airflow and drum speed, or a clear reason why not
Gas or power modulation fine enough to control rate of rise
A way to log data to a computer, for example through thermocouple outputs or a supported connection, so you can record and repeat profiles. See roast logging.

5. Site, safety and emissions

Site questions for every shortlisted machine

Footprint, ceiling height and door width for delivery
Flue route and height; whether the site needs an afterburner or catalytic unit
A chaff collector or cyclone you can reach and empty easily
Built-in fire suppression or a clear fire procedure
Cooling tray capacity that keeps up with the batch size
Noise of fans and blowers if you have neighbours

6. Support in your country

A roaster that is down is a business that is not shipping. Ask every supplier where the nearest engineer is, how quickly parts arrive, what training and commissioning is included, and talk to roasters who already own the model. Imported machines without local support need a plan for parts and servicing. See sourcing a roaster internationally.

7. Total cost

Compare the full installed cost: machine, delivery, installation, gas and electrical work, ducting, afterburner, commissioning, training, spare parts kit and the first service. A cheaper machine with a costly installation is not cheaper.

Where Roastnet helps

Questions roasters ask

What size coffee roaster do I need?: Work back from your target weekly volume in two to three years, roast loss and the hours you want to roast, then allow headroom. Many growing roasteries buy one size larger than they need today.
Is a 5 kg roaster enough to start?: For many new roasteries, yes. It can produce well over 100 kg of roasted coffee a week in a few hours of roasting. Plan for what happens when you outgrow it.
Should I buy a sample roaster too?: If you buy green coffee from samples or develop profiles, a sample roaster saves production batches and green. See the guide on samples and sample roasting.