Abstract The objective of this work was to adjust and validate a mathematical equation to estimate the total leaf area of banana plants of the cultivars Maça BRS Princesa, Prata BRS Platina, Prata Gorutuba and Prata-Anã together, through the linear dimensions of the third leaf and the total number of leaves. For that, the linear first degree and power models were tested, where was used a dependent variable (y) the total leaf area (TLA) an independent variable (x) the multiplication of the length with the total number of leaves (LN), multiplication of the width with the total number of leaves (WN), and multiplying the length by the width with the total number of leaves (LWN). Analysis of covariance was used to test the possibility of using a single equation to estimate the total leaf area of the analyzed cultivars. For all equations, the mean absolute error, the root mean square error and the Willmott d index were obtained as validation criteria. The power model equation TLA = 3.9292(WN)1.5851 can be used simply and quickly to determine the total leaf area of plants of the four cultivars under study.