Days of Supply Calculator
See exactly how many days of stock you have left before a stockout. Add multiple SKUs for a full picture.
Reorderly connects to your Shopify store and handles this automatically — 24/7, without you touching it.
Frequently asked questions
What is days of supply?
Days of supply (DOS) is the number of days your current inventory will last at your current sales rate. A DOS of 14 means you have 14 days before you run out of stock. Most merchants aim to keep at least 30–45 days of supply on hand for their top SKUs.
What is a healthy days of supply target?
It depends on your supplier lead time. A good rule of thumb: your target DOS should be at least 2× your supplier's lead time plus your safety stock. If your supplier takes 14 days, you want at least 30–35 days of supply as a buffer.
How often should I check days of supply?
Ideally daily for fast-moving SKUs, and at least weekly for slower SKUs. Reorderly monitors this automatically and alerts you — or better yet, places the order — when a SKU gets close to the reorder point.