ABSTRACT Umbu (Spondias tuberosa Arruda, Anacardiaceae) is a fruit species native to the semi-arid region of Brazil and economically important for several regions. The objective of this study was to determine equations to estimate the leaflet area of S. tuberosa genotypes. A total of 1,000 leaflets was collected from four genotypes (250 leaflets of each genotype) of S. tuberosa. In each leaflet collected, the length, width, and leaflet area were measured, and the product between length and width was calculated. Linear, linear with intercept, power, and exponential regression models were used to fit the equations. The criteria for choosing the best equation were based on Pearson’s correlation coefficients, Akaike’s information criteria, Willmott’s concordance indices, and root mean square error. The product-adjusted equations between length and width can be used to estimate the leaflet area of all S. tuberosa genotypes. The leaflet area of the species (pooled data) can be estimated accurately and quickly from equations obtained with the linear models without intercept (ŷ = 0.6911*LW) and power (ŷ = 0.7127*LW0.9888). Spondias Arruda Anacardiaceae semiarid semi arid regions S 1000 1 000 1,00 250 (25 genotype measured calculated Linear Pearsons Pearson s coefficients Akaikes Akaike Willmotts Willmott indices error productadjusted adjusted pooled data ŷ 0.6911*LW 06911LW LW 0 6911 0.7127*LW0.9888. 07127LW09888 0.7127*LW0.9888 . 7127 LW0 9888 0.7127*LW0.9888) 100 00 1,0 25 (2 691 07127LW0988 0.7127*LW0.988 712 988 10 1, 2 ( 69 07127LW098 0.7127*LW0.98 71 98 6 07127LW09 0.7127*LW0.9 7 9 07127LW0 0.7127*LW0. 07127LW 0.7127*LW0 0.7127*LW