Does the roasting process lead to weight reduction? If so, what are determining factors? type of coffee? type of roast(dark, medium etc) ?

If you have X lbs of unroasted coffee beans, how much (average) roasted coffee beans you get after roasting?

3 Answers 3


The roasting process leads to water loss in all types of beans. Most beans start off at about 10-12% moisture and end up around 3%. My experience gives about 15% weight loss (shrinkage) for light roasts and around 20% on dark roast profiles.

Example of a dark roast weight loss in my roasterie would be: Starting weight: 240# Roasted weight: 195# Shrinkage = 195/240 = 81% of start weight so 19% loss.

I can't seem to find any online documentation of this. Just daily experience of being a professional roaster.

  • Thanks so much.im planning to start a small coffee roasting business and been studying.
    – BigM
    Commented Jan 29, 2017 at 2:51
  • 2
    @BigM, I was about to say around 20% for regular roasts. When it's not too light or too dark. Of course roasterbob has much more experience, he already gave a nice answer.
    – MTSan
    Commented Jan 29, 2017 at 7:27
  • My experience with Ethiopian natural processed beans is right at 15%. That's for a medium roast level.
    – PJNoes
    Commented Jan 31, 2017 at 23:39
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    Volume also expands with darker roasts expanding the beans more. Almost like puffed rice or something.
    – Nathan
    Commented Feb 1, 2017 at 19:06
  • @PJNoes, Ethiopian naturals tend to have less shrinkage because they tend to start off with a lower moisture content. So by that fact that have less moisture to lose from the get go no matter what roast level Commented Feb 1, 2017 at 23:24

I roast in a bread machine with a heat gun. I roast 567 g per batch (1.25 #). I roast Ethiopian and Kenyan beans. My weight loss is between 12.7% and 16.2% loss. I end the roast at about 210 C (410 F) in about 10 to 12 minutes. If the batch weights in at 500 grams, I delay the cooling until it reaches about 490 grams usually 2 to 3 minutes. Then proceed to stop the roast. Usually the batch will weigh 488 grams which is a city+ for me. My "fireside chat" on Youtube The trout doc has details of process. SH


i roast 2kg Colombian beans at a time (last batch begin 2003g) and end up around 1.6kg (last batch end, chaffed and cooled 1608g) i roast in an oven so need to remove chaff manually (i use a cool hairdryer, fan and a large bowl) so i ended up with a 19.72% reduction (moisture and chaff loss) (1608x100):2003=80.279% so yeah 20% loss for a medium roast, after first crack and before 2nd crack. been cracking beans for over 10 years now. love life love coffee

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