One of the main types of active packaging are oxygen-scavenging films (OSF), which reduce the amount of residual oxygen inside a package. This allows reducing the food deterioration occurring due to oxidation, thus prolonging its shelf life. Currently, our research group has developed polypropylene films with oxygen absorption capabilities through the incorporation of silica nanocapsules containing essential oils as the oxygen scavengers (OS). In this work, a computational tool that allows the determination of the oxygen concentration reduction in a fixed volume due to the action of these OSFs is presented. To carry out this tool, mathematical modeling using the composite film approach was used. For the reactive sites, the Shirking core approximation was applied. Experimental validation of the model was made by means of the oxygen concentration headspace test of the OSFs produced by internal mixer (components mixing) and compression molding (films production). A study of the effect of several design variables such as the film area, thickness and OS load, over the film oxygen absorption performances was made, finding a correlation which predict film lifetime and headspace oxygen final concentration which was used as the main equation for the develop tool.