Roasting your own coffee is really easy and all you need is an oven, a cookie sheet and some green coffee beans

Why?

Even though green coffee beans tend to be heavier due to the higher water content, generally it's cheaper to roast your own compared to buying them pre-roasted.

You can roast the same beans at different levels to get some variety without having to go out and buy a new batch.

It's kind of fun and a decent conversation topic.

Notes

Don't be scared by how long this post is. It basically just comes down to spread beans on a cookie sheet, put in preheated oven, wait around 12-15 minutes and then take them out and cool them.

Since we're talking about roasting beans, naturally you're going to need a grinder to actually use them.

The process will create some smoke, even with a light roast. Basically, darker roast, more smoke. So far I've mainly done pretty light roasts and even though my kitchen doesn't have much ventilation (and my oven doesn't have fancy modern contraptions like, you know, a light or a fan) it hasn't been an issue.

Your oven should be reasonably clean if you don't want the roasted coffee to taste like random stuff.

If you're a super coffee snob and it has to be perfect, this may not be for you. It's pretty easy, but odds are the first few tries aren't going to be perfect especially if you like darker roasts.

You're going to want something like a large metal mixing bowl and colander for the cooling process. My colander is plastic, so you can probably get away with that if you don't put the red hot beans in it directly out of the oven.

You'll also probably need access to an outside area where bits of coffee chaff blowing around aren't going to bother people. I don't think there's really an easy way to deal with coffee chaff indoors.

By the way, don't try to grind green coffee beans in a normal grinder. They are insanely, and I mean insanely hard and tough. You'll destroy your grinder unless it is an absolute tank. (I'd say it's also not really worth trying, green coffee didn't taste very good to me.)

How

Here's the process:

Start preheating your oven to 500f/260c. (Some people say as hot as possible, some people use a slightly lower temperature like 460-475f.)
Get a cookie sheet ready. Just a standard cookie sheet. Mine aren't super clean so I put a layer of silver foil on it. Don't preheat the cookie sheet itself.
Measure out about 1 cup of green coffee beans. (I've found you can fit about 2 cups on a single sheet but it's probably better to start small.) You want to make sure the beans are spread out evenly in a single layer.
Look for beans that are discolored/damaged and toss them away. Don't be a perfectionist though, just get rid of 10-15 of the worst looking beans. Something like that.
Place the cookie sheet in the oven once it's reached the correct temperature. I put mine on the bottom rack near the (electric) heating element. If you're going for a darker roast, I guess this might make burning them more likely.
Set a timer for ~12 minutes. I wouldn't recommend roasting longer than 14 minutes your first time.
Now you wait a bit. Probably around the 8 minute mark, you're going to start hearing sharp cracking/popping sounds. Don't worry, the beans won't jump around like popcorn and the sound is fairly loud so you're not likely to miss it. At this point (or in 1-2 minutes) you can remove the beans and have a light roast. This point is known as the "first crack".
After a couple of minutes, the sounds will die off and you won't hear anything for a little bit. If you keep roasting, you'll start to hear a softer, more muted crackling sound start. This is the "second crack". I would not recommend roasting past this point until you're comfortable with the process and have an idea of how roasted the beans are at this point. If you roast much longer, it's very easy to burn them and there's also going to be a lot more smoke.
Remove the beans from the oven. You can let them rest for 1-2 minutes on the cookie sheet if you want, then transfer to something like a metal mixing bowl. It has to be something that can deal with 500f stuff touching its surface.
Ideally get another mixing bowl/colander/whatever as well. Pouring the beans back and forth through the air is a good way to cool them off and remove chaff. What's chaff you ask? The beans are coated with a papery layer of chaff. Don't worry though, once they're roasted it's really easy to remove. You want to try to cool off the beans pretty quickly at this point.
Go outside and blow gently on the roasted beans in your bowl. You should see a bunch of super light, papery chaff fly out. You can pour the hot beans from one bowl to another, and if there's a bit of a breeze that'll help a lot. Otherwise, you can just blow on them. You could also stir them around with a wooden spoon or something to encourage the chaff to separate.
Once the chaff is mostly gone (it's fine if there's a little left, or little pieces stuck to some beans) and the beans are fairly cool you can just leave them in a safe place for around 12 hours to fully cool and vent CO2. Don't put them in a sealed container for the first 12-ish hours.

Conclusion

One thing to note is you don't want to actually grind/use the beans for at least 12 hours. It might seem unintuitive, but from what I've read as freshly roasted as possible isn't necessarily best. Depending on the beans/roast level, the coffee might reach its optimal tastiness even a couple weeks after roasting.

I'm far from an expert, but feel free to ask questions in the comments if you want. I can recommend a grinder/beans to get started with if anyone needs information like that.

67 comments

The problem with roasting your own coffee is that you don’t have the equipment to control temperature and time precise enough to make sure that no acrylamid or furan is created. Both of those substances are carcinogenic and should be avoided. If you buy roasted coffee it’s always made sure that it is not containing that stuff.
- Bad news. Commercially roasted coffee also contains acrylamide. https://pubmed.ncbi.nlm.nih.gov/24325083/
  
  True but they have to measure the amount and stay below a threshold. You can't guarantee that if you do that at home.
  
  I just switched to drinking tea instead of coffee. My stomach thanks me.
- Thanks for this post. I've been roasting during covid as I couldn't find proper roasted beans, but never knew it could be carcinogenic. I've reverted back to roasted beans as it was just too time consuming and inconsistent, even with a cheap coffee roaster.
- Curious is this more of a concern if you are roasting a dark roast over a light roast? My father in law has been roasting beans for years now. Did not know this was a potential issue.
  Otherwise, his coffee is delicious.
  
  Interestingly, the article linked said that lighter roasts (their metric was by color, but basically it translates to a lighter roast) had more and then the amount gradually decreased after peaking as roasting continued.
  It does mention that none of the coffee samples regardless of roast exceeded the EU's recommended check values. So we probably don't need to panic. I'm also a bit skeptical of the other person's claim about commercial roasters avoiding the issue, especially since it was instantly debunked.
  
  I am not an Coffee expert so can't tell you what's more secure. I think there are lessons you can take to roast yourself wich will help you avoid those carcinogenic being created but would also guess that they will tell you to get better equipment for that and to not just an oven as they are to inconsistent.

You should also know that you will set off every fire alarm in your house

One day I will try this because I love coffee and I like experimenting in the kitchen in general, but the reality is the time and effort required would not outweigh the cost, quality and consistency of a local roaster who can get coffee out to you a couple of days (at most) post roasting especially if I factor in the multiple cups a day I drink!
- but the reality is the time and effort required would not outweigh the cost, quality and consistency of a local roaster
  It really depends on how high your standards are but even my very first attempt tasted like good coffee (to me - admittedly I am not a coffee gourmet by any stretch). It honestly was far easier and less intimidating than I imagined. I'd say the effort level compares to making a batch of pancakes or maybe something like oatmeal cookies which you just mix up and drop onto the cookie sheet.
  The post is long because I wanted to make sure everything was clear and answer potential questions in advance.

Because coffee beans have a flat side, this method will produce an uneven roast. The way I was taught was to use a pan and to stir consistently. You'll still end up with a non-uniform roast, but it should be a bit better then oven roasted.
Cast iron works well because of heat retention and radiative sides. Plus they work great on a grill so all the smoke and chaff stays outside. (My wife doesn't let me roast inside anymore)
But at the end of the day it's not too important how you roast them, just that you are home roasting and enjoying your morning brew.
- Because coffee beans have a flat side, this method will produce an uneven roast.
  Interestingly, when I was researching this I saw some people say they actually referred that for the variety or making the coffee taste more interesting (broader range of flavors getting combined). Not sure I'm enough of a gourmet to really tell the difference, or have a problem with it even if I could. I'd guess it's about the same as just mixing two different roast levels unless you do something that actually hurts the quality like burning some beans.
  The way I was taught was to use a pan and to stir consistently.
  I might try it eventually. I'm super lazy, so just tossing them into the oven and leaving them there is a lot less work than standing at the stove stirring the beans.
  
  I have a grill and air fryer with a rotisserie. Both have basket attachments. Would these work?
  
  If you enjoy the variation, absolutely go for it!
- I recently got into home roasting and it's been awesome. I have a bio light that runs on wood, and I just knocked down a couple trees on my property, so infinite free heat source that I can use outdoors. I also prefer a bit of an uneven roast as well cause it gives you a bit of a black and tan flavor.

When I was a kid, every afternoon my neighbor (an old lady) would sand-roast some coffee beans in a big wok on a wood stove. The smell of the roasted coffee would fill the entire neighborhood. My dad would often send me to buy some of those coffee for like 50 cents. She would make a cone out of a newspaper sheet and put a big scoop of freshly ground coffee there. Oh, and she ground the coffee using a big stone mortar. I'm pretty sure the beans were from her backyard too because her backyard was full of coffee trees. This was in a small village in Sumatra btw.

For me roasting your own beans is a case of “easy to do, difficult to master”. It’s a great hobby dont get me wrong, but the way this post is phrased makes it seem like you’ll be getting amazing results from the get go.
There’s a huge amount of trial and error and even with the best will in the world you might not be able to come close to what a local roaster can provide.
- Also, even if you just account for your own time at minimum wage, the cost calculation collapses pretty quickly.
- It’s a great hobby dont get me wrong, but the way this post is phrased makes it seem like you’ll be getting amazing results from the get go.
  Before I started roasting my beans, I usually bought pretty good quality freshly roasted coffee. For example, something like this: https://www.freshroastedcoffee.com/products/ethiopian-yirgacheffe-fto-coffee
  It's not what millionaires would drink, but it's still much higher quality than the random stuff you'd buy in the grocery store. So far, every batch I've roasted myself so far compares and tastes like good coffee to me.
  "Mastering" it and achieving a perfect roast that a true coffee gourmet will say is 10/10 probably is quite difficult to master. Darker roasts are also harder to get right also (at that point it's easy to burn the beans). I think achieving the level where a normal person will say "this is pretty tasty coffee" is not difficult at all though.
- Yeah I know multiple people who have tried it and said getting consistent results is not easy.
  That aside, unless the process itself is like a hobby to someone, it's almost definitely not worth it from a cost savings perspective. I feel like people often forget the value of their free time. And I doubt I'd ever do any better than one of the local roasters I could buy from.
  Neat to try yourself anyway though. Definitely a process most of us take for granted.
  
  I'll admit to being a hobbyist on the technical side - I went through a couple of moderately expensive home roasting appliances, but I've settled on a $100 rotisserie toaster oven to which I added a $25 PID temperature controller. 18 minutes and I get a nice quarter-kilo of beans. I'm less of a coffee connoisseur - my beans all look the same color, even from batch to batch, and all taste decent - I can't really drink Folgers anymore - but I can't swear that James Hoffman would approve.
  My green beans cost $15/kg, which, because there's some mass loss during roasting, works out to ~ $18/kg roasted. Throw in a round $1 for electricity (1-1.5 kWh/kg). My local specialty roasters are all around $35-40/kg. 4* 20minutes = 1.3 hours, so I could notionally pay myself $14/hr and still break even. I could double the batch size if I were really concerned with time.
  I am still, notionally, paying off those home-roasting appliances, though. They were convenient, but less reliable than the Walmart toaster oven.

The problem with roasting your own coffee is I have a life in a city in the Western hemisphere and nowhere around me sells raw coffee beans.
- You probably also don’t value your time using pennies or fractions thereof on an hourly basis.
  I have no problem with people who enjoy roasting their own beans. The process is fascinating. But when I’m partitioning out my 24 allocated hours in a day, roasting beans makes neither the list of preferred recreational activities nor the top 10 money making (or saving) exercises.
- The problem with roasting your own coffee is I have a life in a city in the Western hemisphere and nowhere around me sells raw coffee beans.
  Does "Western hemisphere" mean the US? If so, it's no problem getting them. Just for example, this is what I have currently: https://www.amazon.com/gp/product/B01GGMF8RA/ (not a referral link or anything)
  https://www.freshroastedcoffee.com/ also sells green coffee beans. Those are ones I've bought from previously without issues. If you live in a different country then it might be harder but it's almost certain that there will be online stores in your country that sell green coffee beans. You might even be able to find local stuff.
  
  I'm all for cooking at home and lots of DIY projects, but I just think this is one thing better left to the pros. Also, yeah I'm in Canada. So I'm sure there are online options, but again, time and equipment are huge factors.

Really cool stuff! But where do you get the beans? I don't think I've ever seen unroasted coffee beans here in Norway.
- In the US, but I got started by mail order, and that's probably your best bet. Shipping costs reduce the economy of it, but if I got 2.5 kg batches, the beans+shipping was about half the cost of roasted. Now, my local farmers market sells them. You might also ask a local coffee shop/roaster if they'd sell you some of their green stock.
- Less than a century ago, coffee roasting at home was still pretty common here. I don't think I've seen unroasted beans offered anywhere in Finland either and I suspect they wouldn't be cheap unless you bought by the sack. And the roast would add to the cost in small batches.
  Would be kind of interesting if you had a group of people maybe. And a source for beans.
  And maybe a solar oven...
  
  Just for price comparison, I bought a 5lb (~2.25kg) bag of organic, fair trade beans for $44USD (back near the end of June and I still have 1/2-1/3 left drinking a pot of coffee most days). So unlike avocado toast, you won't have to take out a loan or pool your resources with the neighborhood to buy it.
  There's a good chance it would be more expensive in Finland than the US. Look on the bright side though, even if you might pay a bit more for your coffee at least you don't have to worry about just being left to die if you run into medical issues. Can't enjoy tasty fresh roasted coffee if you're dead, after all.

Slaps air fryer

Not to be a downer, but you're gonna get a lot of smoke roasting beans in your electric oven (gas would have an exhaust to the outside). That smoke really isn't good for you to breathe in either. Prolonged exposure will lead to "popcorn lung". It's also going to make your stove very dirty in the inside in short fashion. Also, you're gonna melt some plastic colanders if you drop coffee beans into them right out of a 400-500 degree oven. Not to mention that plastic + heat = not good (even without the melting)
If you want to try roasting coffee beans at home once or twice on the cheap, you're better off "pan roasting" them outside on a camp stove or something similar if you don't have an exhaust fan right above your stove that connects to outside.
Specialized at-home electric roasters exist and aren't that expensive. Certainly cheaper than smoke mitigation.
- but you’re gonna get a lot of smoke roasting beans in your electric oven
  There's really not much smoke with light/medium roasts. My kitchen is pretty small and there's a smoke alarm on the wall that doesn't even get set off. For dark roasts it could be a bigger issue.
  Prolonged exposure will lead to “popcorn lung”.
  There's 5-10 minutes at most when the beans will actually be smoking and you're not going to be roasting every day. 2 cups of green beans makes about a pint jar of roasted coffee. I drink a pot of coffee every day and it lasts more than a week.
  Also, you’re gonna melt some plastic colanders if you drop coffee beans into them right out of a 400-500 degree oven.
  I specifically said not to do that. :)
  If you want to try roasting coffee beans at home once or twice on the cheap, you’re better off
  Have you ever actually done it? Not to be confrontational, but I think you're really overestimating the issues. Also, if someone is just doing it once or twice, then long term effects like "popcorn lung" aren't going to matter.
  
  Yes I used to roast at home several times a week on a Behmor machine. There's a reason all the at-home machines (and commercial machines for that matter) have smoke suppression...
- That’s not how you get Popcorn Lung.
  
  During coffee production of both flavored and unflavored coffee, production employees become exposed to dangerous VOCs resulting in irreversible lung damage (Ref. 1). The most hazardous VOCs released from flavorings and naturally from roasting coffee beans are diacetyl and 2,3-pentanedione. Exposure to even small amounts over time or large concentrations over a short period of time can have drastic health effects (Ref. 2).
  https://www.sentryair.com/blog/industry-applications/chemical-solvents/diacetyl-hazards-coffee-roasting-industry/
  (Yes I know they're trying to sell you air filtration systems or whatever... but they reference several scientific studies in their literature)

I imagine it's a much more intensive process, but this kind of makes me want to ferment my own black tea.
- I imagine it’s a much more intensive process, but this kind of makes me want to ferment my own black tea.
  Haha, definitely sounds like it. I found these pretty clear instructions: https://www.ctahr.hawaii.edu/oc/freepubs/pdf/FST-26.pdf
  Just the "gather your tea shoots in a muslin ~~back~~ bag and kneed for 10 minutes" is already more work than roasting coffee even before you read the next sentence "repeat this process 4 times" and then all the other steps.
  Think I'll leave that one to the professionals.
  
  Hmm. Yeah. I'll stick with the pre-bagged.

Is your oven electric or gas?
- electric, it says in the post the heating element is electric, unless it's a recent edit.
  
  Oh I missed that small detail thanks.
- The other person was correct, it's electric.

This is how i started out, but a good old fashioned hand cranked pop corn popper on the stove for roasting up to a 1/2 lb. of green coffee is the best.

67 comments