Log Taper CalculatorDiameter Change and Form Factor Analysis

A log with 2 cm/m taper and 5m length loses roughly 18-25% of sawn lumber vs a uniform cylinder. Tapered logs require offset cuts, wasted edging, and irregular board widths. Mills pay 5-15% less per m3 for Class 3 logs.

For lumber recovery, generally yes — a strongly tapering log yields shorter or narrower boards and more slabwood waste than a cylindrical one of the same butt diameter, because the sawyer has to work around the shrinking width. But taper isn't all downside: it's natural, it tells you something about how the tree grew, and for some products like tapered poles or certain veneer logs it's not a problem at all. The key is to know the taper before you saw so you can plan the cutting pattern around it.

Measure the diameter (inside bark) at both ends of the log, subtract the smaller from the larger, and divide by the log's length to get taper per unit length — that's exactly what this calculator does. For consistency, always measure at the same reference points and take two readings at right angles at each end to average out any out-of-roundness. Doing it the same way every time matters more than the absolute method, so your figures stay comparable from log to log.