Coffee Calculators
Roasting Weight Loss Calculator
https://www.coffeesizing.com/calculators/roasting-weight-loss/
Estimate only — not a cupping score, a water lab or a roast profile. Confirm on a test brew.
Roasting Weight Loss Calculator
Green coffee sheds water and organic mass in the drum. Weight loss is (green − roasted) / green. City / light-medium often sits near 12–14%; darker roast level pushes 16–18% and beyond. It is a kitchen-scale proxy for colour, not an Agtron machine. Log it batch after batch or you are guessing.
Inputs
Results
- Weight loss
- 14.00%
- Roasted yield
- 86.00%
Recommended gear
Roasting thermometer
Mass loss without bean temperature is a diary with missing pages. Probe the mass, not the drum wall only.
Typical range: $20–$80
0.1 g coffee scale
Sample roasts need 0.1 g. Kilogram charges can use a 1 g kitchen scale; pick one and stick to it.
Typical range: $20–$80
Airtight coffee canister
Weigh, then rest. Degassing in a sealed valve bag beats a bowl on the counter.
Typical range: $20–$50
Calculation method
Loss percent is one hundred times (green minus roasted) divided by green. Yield is roasted over green. 1000 g in and 860 g out is 14% loss and 86% yield — a common medium-ish band. If roasted mass exceeds green, the inputs are swapped or wet.
Exact formula
lossPercent = 100 × (greenG − roastedG) / greenG. yieldPercent = 100 × roastedG / greenG. Limits: Chaff in the roasted pan, moisture of the green and cooling-tray spillage omitted; loss is not colour.
Selling roasted coffee
Yield percent is what you can bag from a green invoice. Cost-per-cup tools want roasted grams, not the green price alone.
Frequently asked questions
Do I weigh chaff?
Roasted coffee is beans, not the chaff collector. Including chaff understates loss. Destone, then weigh.
Is 18% always French roast?
Often dark, not always a named grade. Moisture of the green and how aggressive the drying phase was move the same colour to a different loss.
Sample roast versus 1 kg?
Small charges lose heat and can show different loss at the same colour. Compare like with like.
More in this topic
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Bean Degassing Calculator
Estimate a peak flavour window from roast level and days since roast. Light roasts rest longer; dark roasts degas faster. A calendar, not a CO₂ meter.
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Green Coffee Density Calculator
Estimate green bean bulk density from mass and displaced or poured volume. Density hints at heat uptake, not a lab true-density.
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Roast Development Time Ratio Calculator
Compute development minutes and DTR percent from time to first crack and total roast time. A clock ratio, not a colour meter.
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Roasting Rate of Rise Calculator
Compute rate of rise between two bean temperatures over a time interval. RoR is the slope, not a flavour name.