In the field of operations and production management, inventory systems is the most studied aspect due to its high contributions to most companies’ expenses. In that respect, effective stock control is essential to the improvement of many businesses. Problems arise, however, when conducting inventory management due to the many uncertainties faced. In this paper, the researchers address issues concerning the said uncertainties in inventory management through forecasting and supply chain integration in an inventory simulation model via Microsoft Excel and Visual Basic applications. The proposed model incorporates information coming from downstream tiers of the supply chain in computing the forecasts. The model was tested using a set of heuristic data using the incurred costs as performance measure. The findings show that the proposed model, in comparison with basic and classical forecasting and inventory management models, performs significantly better under the different conditions tackled in the study. The findings also suggest that the proposed model could be the basis of more complex inventory management models.