Core Formulas

How to Calculate Board Foot Yield, Pulp Yield, and Trim Waste in Wood and Paper Manufacturing

Work through the five core calculations that govern yield and waste in wood, pulp, paper, and corrugated plants, with real units and numbers you can reproduce.

Board foot yield starts with the Doyle or nominal rule. A board foot equals 144 cubic inches, so a 1 inch by 6 inch by 8 foot board is (1 x 6 x 96) / 144 = 4 board feet. From a log, gross scale minus defect gives net scale, and yield is net lumber tally divided by log scale. A 300 board foot log scaled by Scribner that cuts 210 usable board feet returns 210 / 300 = 70 percent overrun-adjusted yield. Pull the log scale from the scale ticket and the tally from the green chain count. The Board Foot Yield calculator handles the 144 divisor and the rule conversion so you avoid mixing Doyle and Scribner.

Saw kerf loss is the sawdust volume destroyed at each cut. Kerf width for a thin-kerf circular blade runs 0.09 to 0.125 inch; a band mill runs 0.035 to 0.075 inch. For a cant sliced into boards, loss fraction equals kerf / (board thickness + kerf). Cutting 1 inch boards with a 0.125 inch kerf loses 0.125 / 1.125 = 11.1 percent to sawdust before any drying. Drop kerf to 0.045 inch on a band saw and loss falls to 4.3 percent, recovering roughly 7 board feet per 100. The Saw Kerf Loss calculator multiplies this across every cut line in the sawing pattern.

Pulp yield is oven-dry pulp produced divided by oven-dry wood consumed. Chemical kraft pulping yields 45 to 55 percent because lignin and hemicellulose dissolve; mechanical and TMP pulping hits 90 to 95 percent because fiber stays intact. If 2,000 kg oven-dry chips produce 950 kg oven-dry kraft pulp, yield is 950 / 2000 = 47.5 percent. Correct both streams to oven-dry mass first using measured consistency, never green weight. The Pulp Yield calculator lets you enter consistency and moisture so the ratio stays on a bone-dry basis rather than a wet basis that inflates the number.

Moisture loss drives every mass balance in drying. Use bone-dry basis: moisture content equals (wet mass minus dry mass) / dry mass. A sheet entering the dryer at 55 percent moisture wet basis and leaving at 6 percent has water removed equal to the difference in water mass per unit fiber. For 1,000 kg wet stock at 50 percent wet-basis moisture, fiber is 500 kg; drying to 8 percent wet basis means final mass is 500 / 0.92 = 543 kg, so 457 kg of water evaporated. The Moisture Loss Calculator flips between wet and dry basis, the single most common unit error in this category.

Paper trim waste is the slit-off edge and pattern loss when you cut narrow rolls or sheets from a wide parent reel. Trim loss fraction equals (parent width minus sum of ordered widths) / parent width. A 2,800 mm reel cut into three 900 mm rolls uses 2,700 mm and trims 100 mm, a 3.6 percent loss. Add the fixed edge trim, often 10 to 25 mm per side for wet-edge instability. The Paper Trim Waste calculator solves the roll-set combination that minimizes leftover width, which is where most planners give back 2 to 4 points of yield.

Converting throughput ties speed to good output. Effective rate equals line speed times web width times run time times yield, minus roll change and splice downtime. A corrugator at 250 meters per minute, 2.2 meters wide, running 400 minutes with 92 percent good yield produces 250 x 2.2 x 400 x 0.92 = 202,400 square meters. Every roll change that stops the web 90 seconds at that speed forfeits 250 x 1.5 x 2.2 = 825 square meters. The Converting Throughput and Roll Change Loss calculators separate the speed term from the interruption term so you can see which one is capping output.

Carton blank utilization measures how much of the corrugated or board sheet becomes finished blanks. Utilization equals total blank area divided by sheet area. A 1,200 mm by 800 mm sheet holding four blanks of 560 mm by 380 mm uses 4 x 560 x 380 = 851,200 mm squared out of 960,000, so 88.7 percent, with 11.3 percent skeleton and trim scrap. Nesting a fifth blank by rotating the layout can lift this to 92 percent. The Carton Blank Utilization calculator tests orientations and gutters so the sheet size you order matches the die layout instead of paying for waste corners.

Chain these into one balance and you can predict finished output from raw input. Take 100 board feet of green log, lose 11 percent to kerf, 6 percent to drying shrinkage across the grain, and 4 percent to trim and defect, and you net roughly 79 board feet dry and dressed. On the fiber side, 1 tonne of oven-dry wood at 48 percent kraft yield gives 480 kg pulp, which at 92 percent machine efficiency and 3.6 percent trim yields about 426 kg salable paper. Run each calculator in sequence and the compounding losses become visible instead of hiding inside a single fudged recovery factor.

Published 2026-07-01.