The impact of measuring trees at 1.3 m versus 1.37 m heights above ground line was analyzed. The results indicate that the difference in diameter measurement taken at the two points averages around 1 percent. An equation for converting from English diameter at breast height to the metric equivalent of 1.3 m is presented.
United States Department of Agriculture, Forest Service, "Tree Diameter Measurements at English and Metric Standard Heights: A Comparison" (1984). Forestry. Paper 34.