inventory aging presentation

Date of Manufacture should  be the base for aging of Inventory based on that as per shelf Life of the goods ascertain whether it is slow moving or Non Moving

and to track manually in a spread sheet note down all stock Keepng Units (for Brevity termed as SKU) and enter the manufacture date from the Batch and if the shelf Life of Your product is say 1Year from the date of Manufacture accordingly age inventory as good stock,slowmoving stock,non moving stock etc