Determination of the sample size for accurate estimation of girth records is a basic necessity in sampling plans. This study was focused on the above objective and analyses were carried out using secondary data on girth, obtained from immature rubber holdings covering seven rubber growing districts. The coefficients of variation (CV) gor girth were calculated for each rubber holding and averaged accordingly, to study the change in CV (i) with age (ii) in different districts (iii) with the varying extents (iv) with the type of clone (v) with the type of planting material, and (vi) with the stand per ha. in a rubber holding. Subsequently, a sampling guide is proposed based on the average CV for varying conditions and the accuracy needed on the estimation of girth.