The mathematical modeling used to predict the steady-state O2 partial pressures for design of modified atmosphere (MA) packages of avocado (Persea americana ‘Fuerte’) fruits was developed. The rate of O2 uptake (RO2) was determined as a function of O2 partial pressures by mathematical characterization of O2 depletion data collected by avocado fruits in a closed system with time. RO2 was used to describe the modeling of packaging ratios (A/Wp) characteristics (film surface area (A), fruit weight in packages (Wp) ) as a function of film permeability to O2 (PO2) (O2 permeability coefficient, thickness) to achieve desired O2 partial pressures of the sealed package for MA packages of avocado fruits. Prediction curves showing steady-state O2 partial pressures for packaging ratios in the range of 1.5 to 8.6 closely resembled the curves of experimental data. Maximum benefits (for example, weight loss, firmness, visually assessed mean pericarp coloration (brownness) and visual quality of fruit) for avocado fruits in MA packages were obtained when the O2 partial pressures inside the package was maintained in the range of 1.5 kPa at 20°C. As a result, film specifications and optimization of packaging ratios for avocado fruits in MA packages were calculated based on desired steady-state O2 partial pressures.