How the math works
You pay for green coffee by the pound, but you sell roasted coffee. Roasting makes the beans lighter, so each roasted pound took more than one green pound to make. The calculator divides your green price by the share of weight that is left after roasting:
- Roasted cost per pound = green price ÷ (1 − roast loss)
- Coffee cost per bag = roasted cost per pound × bag weight in pounds
- Cost per bag = coffee + packaging + work time + shipping or other
- Coffee cost per cup = roasted cost per pound ÷ 453.59 grams × grams per cup
- Margin = selling price − cost per bag. Margin % is that, divided by the selling price (not by cost, so it is not markup).
One pound is 16 ounces, or 453.59237 grams. Those are the only fixed numbers in the tool. Everything else is yours.
What roast loss is
Green coffee holds water. In the roaster, heat drives most of that water out, and a little of the bean leaves as gas and chaff. So a pound of green coffee comes out weighing less than a pound. The share it lost is your roast loss.
It changes with the coffee, the roast level and the machine. Darker roasts stay in longer, so they usually lose more. The best number is the one you measure: weigh a batch going in, weigh it coming out, and divide the weight lost by the starting weight. If you roast several coffees, measure each one.
Why cost per bag matters for wholesale
A café buying from you pays less per bag than a shopper does, so there is less room between your cost and your price. A few cents missed on each bag does not look like much. Multiply it by every bag you ship to every café, every week, and it is real money.
The costs people forget are the small ones: the valve, the label, the ten minutes of bagging. That is why the calculator asks for them. Know your floor before you quote a wholesale price, not after.
How to use your result
Your cost per bag is your floor. Sell below it and each bag loses money. Put your retail price in the selling price box, note the margin, then try your wholesale price. Run it again when your green price changes.
If you run a café, the cost per cup shows what the coffee in one drink costs you. It does not include milk, cups, lids or staff time. Add those on top when you price a drink.
What this leaves out: rent, power and gas for the roaster, equipment, bad batches, samples and card fees. If you know what those come to per bag, add them in the shipping or other box.