The proper form factor for desired species is essential for estimating the volume of standing trees. Accurate volume equations for Eucalyptus camaldulensis are not available in Nepal, leading to a hampered estimation of sustainable harvest rates due to the use of a simple approximation for all species, regardless of their height and diameter. This study aimed to estimate form factors for both overbark and underbark diameters of stem and wood for accurately predicting the volume of standing trees. A random selection of 51 sample trees representing diameters above 20 cm was made. The overbark diameter at heights of 0.15, 0.3, 0.8, and 1.3 m was measured before harvesting, while the remaining diameters were measured after harvesting. Diameters were recorded at 1 m length intervals from a height of 2.3 m on the stem and from the crown height down to branches until the diameter reached 10 cm. After felling, the underbark diameter and the total height of the trees were measured. The form factor was determined by the ratio of the volume of a tree to the volume of a cylinder (the product of its basal area and height). The data were analyzed qualitatively and quantitatively using MS Excel, SPSS, and R software programs. The analysis resulted in an average form factor for eucalyptus wood, with overbark at 0.368 and underbark at 0.320, while the form factor for the stem was 0.355 overbark and 0.309 underbark. The results indicated that the form factor for the stem decreases with increasing diameter but decreases until the 35–40 cm diameter class and increases for diameters greater than 40 cm for wood. It was concluded that the default form factor of eucalyptus, i.e., 0.5, overestimates the volume of standing trees. The FF models were tested, and Mayer’s function was found to fit for the stem, while the Australian function was appropriate for wood. Using form factors according to diameter classes and height will allow for more accurate predictions of standing volume of the trees.
Jnawali et al. (2026) studied this question.