Calculateur de perte de poids à la torréfaction du café
Le café vert se contracte en torréfiant. Convertissez le poids vert en poids torréfié selon le niveau de torréfaction — ou pesez votre lot pour trouver la perte réelle.
Calculateur
Planifiez votre lot
Pour obtenir 850 g de café torréfié avec 15% de perte, partez d'environ 1000 g de grains verts. Les plages de perte à la torréfaction sont indicatives — l'humidité, la densité des grains et le temps de torréfaction modifient tous le résultat.
À propos de ce calculateur
Coffee loses weight when it roasts. Most of that is moisture driven off as the beans heat, plus a little dry matter (chaff and CO₂). A light roast typically loses around 11–13% of its green weight; a dark roast can shed 17–20%. This calculator converts your green (unroasted) weight to a predicted roasted weight by roast level, and works backwards so you can plan how much green to load to hit a target roasted batch. Already roasted? Weigh the batch and it shows your actual loss instead.
Comment lire vos résultats
Pick your green weight and a roast level — the loss% snaps to that level’s typical midpoint, and the fine slider lets you nudge it. The hero is the predicted roasted weight; the stats show the grams lost, the loss percentage, and the indicative band for that roast level. If you enter a measured roasted weight, the calculator switches to your real loss% (green − roasted ÷ green) and the hero shows that figure instead.
Méthode de calcul
Roasted weight = green × (1 − loss% ÷ 100). Weight lost = green − roasted. When you weigh the roasted batch, the actual loss% = (green − roasted) ÷ green × 100. The reverse plan uses green needed = roasted ÷ (1 − loss% ÷ 100). Indicative loss bands: light 11–13%, medium 14–16%, medium-dark 16–18%, dark 17–20%.
Exemple concret
1000 g of green coffee at a medium roast (≈15% loss).
You should end up with about 850 g of roasted coffee, having lost ~150 g (15%). To roast 850 g again at the same loss, load about 1000 g of green.
Questions fréquentes
Why does coffee lose weight when roasted?
Green beans hold 10–12% moisture, and most of that evaporates during roasting. A smaller part of the loss is dry organic matter — chaff that flakes off and CO₂ released as the beans develop. Darker roasts spend longer in the heat, so they lose more.
How accurate is the loss percentage?
The bands are indicative starting points. Real loss depends on the bean’s starting moisture, density, processing (washed vs natural), the roaster, and exactly how dark you take it. For a true figure, weigh the green in and the roasted out and let the calculator compute it.
Should I buy green by green or roasted weight?
Green coffee is sold by green weight, so factor in the loss when planning. If you want 1 kg of roasted medium coffee, buy roughly 1.18 kg of green (≈15% loss) to allow for shrinkage.
Does a higher loss mean a better roast?
No — loss is just a by-product of how much moisture and matter left the bean. Roasters track it for consistency and yield, not as a quality score. Two roasters can hit the same colour with slightly different losses.
Sources
- royalcoffee.com/understanding-roast-yield-and-loss
- library.sweetmarias.com/how-to-calculate-weight-loss-in-coffee-roasting
- hoos.coffee/blog/why-take-weight-loss-percentage
Révisé par l'équipe YouCalc · Dernière révision
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