This study introduces a mathematical model to describe the floating effects of the top roll in sugarcane mills. The model is developed from experimental data measured during the operation of a sugarcane mill. The measured data is fitted using the top shaft rotation period of the mill and dividing on intervals to individually fit each interval obtaining a function defined by parts. The resulting model shows a correlation coefficient of R2 ≥ 0.97. This allow including the floating effect in the study and design of other elements of sugarcane mills.