Converting Math

How to Calculate Label Yield, Web Waste, and Press Throughput

The core converting formulas, computed step by step with real substrate widths, run lengths, and press speeds so you can reproduce every number.

Start with substrate yield because everything downstream depends on it. Yield is labels per linear foot times usable length. If a 13 inch web carries 4 lanes of 3.5 inch labels with a 0.125 inch gate margin each side, usable width is 13 minus 0.25, or 12.75 inches, giving 3 lanes at 3.5 inch pitch (10.5 inches used) plus scrap. Down-web, at a 2 inch repeat you get 6 labels per foot per lane, so 18 labels per linear foot. A 5,000 foot roll yields 90,000 labels gross before any loss. The Substrate Yield calculator handles multi-lane nesting and gutters so you do not misjudge lane count.

Web waste converts that gross yield into net good product. Web Waste is the sum of makeready length, splice and roll-change stubs, defect stops, and end-of-run trim, divided by total web consumed. On a 5,000 foot run with 220 feet of makeready, two 30 foot splices, and 90 feet of defect purge, waste is 370 divided by 5,000, or 7.4 percent. Net good footage is 4,630 feet, so good labels fall from 90,000 to about 83,340. Always express waste against total web fed, not against ordered quantity, or you will understate scrap by the good fraction.

Flexo makeready loss is its own line because it is fixed per job, not per foot. The Flexo Makeready Loss calculation is press speed times the setup minutes it takes to hit register and target density. At 400 feet per minute with an 18 minute makeready that includes plate mounting proofs and color pull, you burn 400 times 18, or 7,200 feet, plus roughly 15 percent for the ramp where speed climbs from 0. Call it 8,280 feet of makeready waste. Spread across a short 4,000 foot order this is catastrophic; across 40,000 feet it is a rounding error, which is why run length dominates unit math.

Ink usage is grams per thousand impressions, derived from coverage, anilox volume, and transfer efficiency. Ink Usage equals printed area times coverage times film thickness times ink density, divided by transfer losses. A 2.5 billion cubic micron per square inch anilox lays down roughly 2.5 grams per square meter of wet film at full coverage. For a 3.5 by 2 inch label at 30 percent coverage, printed area is 0.0045 square meters, so ink per label is about 0.0045 times 0.30 times 2.5, or 0.0034 grams. Across 83,340 good labels that is 283 grams of one color before purge and washup allowance.

Press throughput and roll-to-roll timing turn footage into hours. Press Speed effective rate is nameplate speed times uptime fraction. A press rated 500 feet per minute running at 78 percent utilization delivers 390 effective feet per minute, or 23,400 feet per hour. The Roll-To-Roll Throughput calculator adds roll-change dwell: at a 6,000 foot roll and a 4 minute change, you lose 4 minutes every 15.4 minutes of run at 390 fpm, dropping effective output near 20,600 feet per hour. Our 4,630 net good feet then needs roughly 13.5 minutes of scheduled press time.

Die cut yield closes the loop between printed web and shippable labels. Die Cut Yield is good die-cut pieces divided by pieces entering the die station, capturing matrix-strip breaks, missed cuts, and register drift that scraps otherwise-good print. If 83,340 labels reach the die and you lose 1.2 percent to matrix breakout and edge lift, you ship 82,340. Chain the ratios: gross yield times (1 minus web waste) times (1 minus die loss) equals net saleable. Multiplying stage yields rather than adding losses is the step most operators get wrong, and it changes the shipped count by hundreds.

To reproduce a full job, run the chain in order and keep units rigid. Convert every dimension to a single system first, inches or millimeters, then feet or meters for length, and grams for ink. Compute substrate yield per linear foot, multiply by roll footage for gross count, subtract makeready and web waste to get net footage, apply die cut yield, and finally divide press time to schedule. For the example: 18 labels per foot, 5,000 feet, 7.4 percent web waste, 1.2 percent die loss lands at 82,340 shippable labels from 90,000 gross, an 8.5 percent total shrink you can defend line by line.

One check catches most arithmetic errors: verify that lane count times down-web repeat count equals your labels-per-foot input before you scale to the full roll. If usable width divided by label pitch is not a clean integer, you are either overstating lanes or ignoring gutter width, and every downstream number inherits the error. Recompute usable width as web width minus both edge margins minus (lanes minus 1) times inter-lane gap. Getting lane nesting right at the top of the Substrate Yield step is worth more than any refinement at the die cut stage.

Published 2026-07-01.