How much weight does coffee lose when roasted?

Commonly somewhere around 12% to 20%, more for darker roasts. It varies with the coffee's moisture and density and with your profile, so measure your own.

How much green coffee do I need for 1 kg of roasted coffee?

Divide 1 kg by (1 minus your roast loss). At 15% that is about 1.18 kg of green.

Does roast loss tell me the roast degree?

It correlates with it and is a useful consistency check, but colour measurement and cupping are better guides to roast degree.

Roast loss and shrinkage: where your kilos go

Every kilo of green coffee comes out of the roaster lighter. How much lighter depends on the coffee and the roast, and it changes your cost per kilo more than most price negotiations.

6 min read Updated 9 October 2026

Roast loss is the weight lost between green coffee going into the roaster and roasted coffee coming out, as a percentage of the green weight. Most of it is water: green coffee typically holds around 10% to 12% moisture. The rest is organic matter driven off as gases, and chaff.

Typical ranges

Worked example

Roast loss by roast degree, typical ranges

Light (filter)11 to 14%
Medium14 to 17%
Medium-dark (espresso)16 to 19%
Dark18 to 22%

Indicative ranges only; your own figures depend on the coffee's moisture, density, processing and your profile. Measure every batch.

How to measure it

Weigh the green charge and the roasted output of every batch on the same calibrated scale, after cooling and before any is taken for samples. Roast loss = (green weight minus roasted weight) divided by green weight. Record it in the batch log. Over a few weeks you will have a reliable figure for each coffee and profile.

What it does to cost

Green cost per roasted kilo is green price divided by (1 minus roast loss). At £9.00 per kg green, a 14% loss gives £10.47 per roasted kilo, while an 18% loss gives £10.98. That half a pound per kilo is often more than the discount you negotiated on the green.

Other shrinkage

Destoner and handling losses: spilled beans, stones, defects removed.
Sample roasts and QC cups: small, but count them.
Overruns: batches rounded up and roasted coffee that ages out.
Packing tolerance: filling above declared weight to stay legal under the average system. See coffee labelling.
Moisture loss in storage: green coffee can lose weight slowly in dry storage.

Reconcile monthly

Once a month, compare green coffee used (opening stock plus purchases minus closing stock) with roasted coffee sold and in stock. The gap is your total shrinkage. If it is larger than your logged roast loss explains, look at overfilling, waste and unrecorded samples.

Shrinkage controls

Green and roasted weights recorded for every batch
Roast loss averaged per coffee and profile, updated monthly
Pack fill weights checked against the target
Monthly reconciliation of green used vs roasted sold

Where Roastnet helps

Questions roasters ask

How much weight does coffee lose when roasted?: Commonly somewhere around 12% to 20%, more for darker roasts. It varies with the coffee's moisture and density and with your profile, so measure your own.
How much green coffee do I need for 1 kg of roasted coffee?: Divide 1 kg by (1 minus your roast loss). At 15% that is about 1.18 kg of green.
Does roast loss tell me the roast degree?: It correlates with it and is a useful consistency check, but colour measurement and cupping are better guides to roast degree.