Labels per ribbon formula
Usable ribbon length is reduced by your waste percentage, then divided by label pitch. If multiple labels are printed across the web at the same time, each repeat can produce multiple labels.
Usable ribbon = ribbon length × (1 − waste %)
Labels per ribbon = floor(usable ribbon ÷ pitch) × labels across
Ribbons needed = ceil(target labels ÷ labels per ribbon)
Labels per ribbon = floor(usable ribbon ÷ pitch) × labels across
Ribbons needed = ceil(target labels ÷ labels per ribbon)
Why this is an estimate
Some printers backfeed, pause, calibrate or leave leader/trailer ribbon that changes consumption. Use the waste field to match your own process after comparing the estimate with actual ribbon usage.