Volume is important in updating and projecting inventories, determining harvest level or allowable cut, scheduling the harvest unit for logging, analyzing potential alternatives stand treatments and determining site-productivity. Inherent in the preparation of a forest management plan, an annual forest working plan and a forest harvesting plan is the availability of a volume table, which is usually derived from a functional relationship using a diameter and/or a log length or tree height. Four unweighted and five weighted volume equations were fitted by the method of least squares to volume data of each of the two species groups of Dipterocarp Merantis - Dark Red Meranti (DRM) and Light Red Meranti (LRM) obtained from the mixed tropical forest of Malaysia. Furnival`s Index (FI) was used as the criterion for selecting the best fit regression equation of each species group under study. The equation weighted by 1/D2H showed its superiority over other equations in both species groups. The standard volume equations selected are as follows:

DRM: V = -0.5994 + 3.1947E-04D² + 0.0370H + 4.2054E-05D²H
(FI = 0.9474)
LRM: V = 0.2059 + 1.6593E-04D² + 8.3346E-03H + 4.8974E-05D²H
(FI = 0.9434)
Where,
V is the commercial tree volume (m3 overbark), D is the reference diameter or dbh (cm) and H is the total commercial log length (m) up to the first large branch below the crown base or up to the 30cm end diameter. The standard volume equations obtained from this study were compared with the existing volume equations by FAO (1973) and Canonizado and Buenaflor (1977).