Roasting Math

How to Calculate Roast Yield, Moisture Loss, and Throughput in Coffee and Dry Goods Processing

The core math for coffee roasting and dry goods lines comes down to a handful of mass and rate formulas. This guide works each one with real units and numbers.

Roast batch yield is the anchor calculation. Yield equals roasted mass divided by green mass, times 100. Load 120 lb of green coffee, pull the drop at 100.2 lb, and yield is 100.2 / 120 = 83.5 percent, meaning 16.5 percent weight loss. Light city roasts typically hold 84 to 86 percent yield, medium roasts 82 to 84 percent, and dark or Vienna roasts 80 to 82 percent because more moisture and organic mass burn off. The Roast Batch Yield calculator takes green weight in and roasted weight out; the inputs come from a certified floor scale weighed before charge and again within two minutes of drop, before the beans equalize with room humidity.

Moisture loss is a subset of total loss and worth separating because it drives roast profile decisions. Green coffee arrives at 10 to 12 percent moisture by weight; roasted coffee finishes at 1.5 to 3 percent. Moisture loss percent equals (initial moisture minus final moisture) divided by (100 minus final moisture), times 100. For 11 percent green to 2 percent roasted, that is (11 minus 2) / (100 minus 2) = 9.18 percent of the batch mass lost as water alone. The Moisture Loss calculator wants the two moisture readings from a benchtop meter or loss-on-drying oven; the rest of your yield loss, roughly 7 to 8 points, is organic mass and chaff, not water.

Grinder throughput sets the pace of any packaging line fed by ground product. Throughput in lb per hour equals mass processed divided by run time. If a burr grinder clears 45 lb in 6 minutes, that is 45 / (6 / 60) = 450 lb per hour, but derate for hopper refills and jams. Real sustained rates on a 5 hp commercial burr unit run 300 to 500 lb per hour for espresso-fine grinds and 600 to 900 lb per hour for coarse drip. The Grinder Throughput calculator uses batch weight and timed run; measure across at least three full hoppers so refill gaps are captured in the denominator.

Packaging line output ties throughput to sellable units. Output in bags per hour equals 3600 seconds divided by cycle time per bag, times mechanical uptime. A form-fill-seal machine at 4 seconds per bag runs 3600 / 4 = 900 bags per hour theoretical; at 88 percent uptime that is 792 bags per hour actual. For 12 oz retail bags that is 792 times 0.75 lb = 594 lb of finished goods per hour. The Packaging Line Output calculator takes cycle time and uptime; pull cycle time from the machine PLC counter over a full shift, not the nameplate rating, because splices and film changes eat 10 to 15 percent.

Energy per batch matters for cost and for sizing gas or electric service. Energy per batch equals burner rating times firing time times average duty cycle. A 210,000 BTU per hour drum roaster firing for 12 minutes at 55 percent average duty draws 210,000 times (12 / 60) times 0.55 = 23,100 BTU per batch. Divide by roasted pounds to get intensity: 23,100 / 100 lb equals 231 BTU per lb. Drum roasters commonly land at 1,800 to 3,500 BTU per lb including warmup and between-batch idle. The Energy Per Batch calculator needs burner rating, active minutes, and duty; get duty from the gas modulation log or a clamp meter on electric elements.

Flavoring usage is a straight ratio but easy to botch on scale-up. Flavor mass equals base mass times target inclusion percent. Flavored coffee typically runs 2 to 4 percent flavor oil by weight; for a 50 lb batch at 3 percent that is 1.5 lb of oil, applied warm and tumbled 8 to 12 minutes for even coating. The Flavoring Usage calculator multiplies batch weight by your inclusion rate and back-calculates cost per pound. Confirm the target against your specification, because moving from 3 to 3.5 percent on a 50 lb batch adds 0.25 lb of oil per batch and shifts both flavor intensity and finished cost.

Labor per pound closes the loop between people and product. Labor hours per pound equals total crew hours divided by pounds produced in that window. A three-person crew working an 8 hour shift is 24 labor hours; if they move 4,800 lb finished, that is 24 / 4,800 = 0.005 labor hours per lb, or 18 seconds of labor per pound. The Labor Per Pound calculator takes crew count, hours, and output. Time the full window including changeover and cleaning, because a Changeover Cleaning Time of 40 minutes between two 90 minute production runs is nearly 20 percent of paid time that most operators forget to load into the per-pound figure.

Chain these together and every number feeds the next. Green in and yield give roasted pounds; roasted pounds set grinder run time; grinder rate feeds packaging output; packaging output and crew hours give labor per pound; burner minutes give energy per pound. Work them in that order with measured inputs, not nameplate assumptions, and the batch reconciles: 120 lb green at 83.5 percent yield is 100.2 lb roasted, ground at 450 lb per hour in 13.4 minutes, packed into 133 twelve-ounce bags at 792 bags per hour, using 231 BTU per lb and 0.005 labor hours per lb. Every downstream cost and benchmark starts from these five calculations done cleanly.

Published 2026-07-01.