How to Use the Coffee Roast Weight Loss Calculator
Roasting green coffee drives off moisture and carbon dioxide, which noticeably reduces the bean's weight. This calculator takes your green bean weight and target roast level (light, medium, or dark), then estimates the roasted weight and how much was lost.
As a rule of thumb, light roasts lose around 12% of their weight, medium roasts around 15%, and dark roasts around 19%. The longer and hotter the roast, the more moisture and organic compounds evaporate from inside the bean, and the more oil and chaff flake off the surface — so weight loss climbs as the roast gets darker.
These figures are averages that can shift a bit depending on the bean variety, processing method (washed vs. natural), and your roaster. If you're roasting a bean for the first time, use this calculator to estimate the yield, then log your actual result — that history makes future batches easier to plan precisely.
Frequently Asked Questions
Roasting longer at higher temperatures drives off more moisture and organic compounds from inside the bean, and more oil and chaff flake off the surface. The darker the roast, the higher the weight loss.
Bags sold at retail are almost always roasted weight. If you're buying green beans to roast at home, this calculator helps you estimate how much finished coffee you'll end up with at your target roast level.