One pleasure of roasting coffee at home is taking a bag of green coffee you like and gradually finding the roast you want to drink. When you look for your first roaster, it is easy to think: if you are buying one, why not go bigger, roast enough on the weekend for the week ahead, and leave less to do during the week?
But you still have to drink the coffee you roast. If you go through one bag a week but want to try several coffees, the convenience of a large batch can quickly leave a few bags in the cupboard waiting to be tasted. The right batch size depends on both how much coffee you drink and how you want to practise.
First, see how long your coffee at home lasts
Rather than guessing whether you are a light or heavy user, start with what you weigh for each brew. At one cup a day and 15g per cup, you will use 105g of roasted coffee a week; two cups a day comes to 210g. If you use a 20g recipe, brew for family, or keep adjusting espresso, include those amounts too.
One detail is easy to miss: a roaster's batch size is the weight of the green coffee you put in. The amounts above are for roasted coffee, which is what you weigh for brewing. Roasting reduces the beans' weight.
Using a 15% loss as an example, 105g of roasted coffee requires about 124g of green coffee, and 210g requires about 247g. The calculation is “roasted coffee needed ÷ 0.85.” The 15% is only a convenient example; weight loss varies with the beans and roast level. Once you start roasting, use your own input and output weights instead.
The same 210g a week can call for different roaster sizes
Suppose you need about 247g of green coffee a week, mostly drink the same coffee, and want to roast it all in one weekend batch. You will need a machine that can handle that batch size. If you want to alternate between two coffees, two batches of about 124g can cover roughly the same weekly use.
Weekly use tells you the total amount, but not how much you want to roast at a time. That is why a smaller roaster can still appeal: when you want to try another roast, you do not have to commit as much green coffee at once.
There is a real cost to splitting the roast. Each extra batch means another round of preparation, roasting, cooling, and cleaning. If you look forward to roasting one batch and taking your time over the coffee afterward, splitting the same amount into many small batches can turn a hobby into work.
Beyond maximum capacity, what range suits regular practice?
For a first roaster, we start by comparing the batch size you expect to use regularly with the manufacturer's recommended range. A label that says “maximum 400g” still does not tell you whether your usual batch is a good fit.
| Model | Manufacturer's recommended green coffee batch size | Maximum green coffee batch size |
|---|---|---|
| M1 | 50–150g | 200g |
| M2 | 50–300g | 400g |
| M6 | 200–600g | 700g |
| M10 | 300–1,000g | 1,200g |
The table follows the official KALEIDO product pages for M1, M2, M6, and M10; check the exact specifications for other models or configurations. In the example above, a regular batch of about 124g is a reason to compare the M1 and M2. For a batch of about 247g, the M2's recommended range fits that plan better.
If your regular batch is above the M2's recommended range, compare the M6; a batch of about half a kilogram falls within its range. If you need to roast more, compare the M10. When you are starting out, keeping to a suitable batch size makes it easier to see which adjustment accounts for a difference from one roast to the next.
Before you begin, plan for everything beyond the beans
In our 2023 record of our first roast with the M1, we spent time before switching on to sort out the green coffee, power, and where to set up. Details that are easy to overlook while choosing a machine become part of the job when you roast at home.
Where will you put the weighed green coffee? Is there room around the roaster while it heats? Where will the exhaust go? Where will the beans cool after roasting? Measuring the machine alone can leave out all of these spots.
At home, follow the manual for safe clearances, ventilation, and the power requirements for the exact version. A built-in exhaust design does not mean you can ignore smoke indoors. If you have not planned the roasting area, sort that out first; it is easier than rearranging the kitchen after the machine arrives.
Choose the controls to match how you want to record each roast
Once you have settled the batch size and setup, Smart, Artisan, and dual-system versions are easier to compare. Coffee Stage's current KALEIDO listings offer these control options; check the product page for the exact configuration of each model.
If you want to work from the roaster's touchscreen, compare the Smart version. If you want to record and analyze roast curves on a computer, consider an Artisan version and plan for the computer and connection. Look at a dual-system version if you have a clear use for both systems.
For a first roaster, being willing to use it often matters more than keeping a lot of capacity you do not yet need. If you like roasting small batches to try different coffees, compare the batch sizes and versions of the M1 and M2; if each batch needs more room, then look at the M6 and M10.
If you are unsure how much you use, start keeping notes with your next bag of coffee. The Roaster collection has current configurations and prices; our first-roast record above can help you decide whether you enjoy the preparation and experimentation too.
Does one cup a day automatically mean choosing the M1?
It also depends on the dose per cup, whether you roast for family, and whether you want to try several coffees at once. With 15g a day, seven cups a week, and 15% roast loss as an example, you need about 124g of green coffee. You can roast that weekly amount in one batch or several; choose a machine for the way you plan to roast.
Can you buy a larger roaster and use it for smaller batches later?
First check the manufacturer's recommended range for that model. The recommended starting batch sizes for the M6 and M10 are 200g and 300g, respectively. If your usual batch is much smaller, compare a model designed for smaller batches instead.
