Reorder Point & Safety Stock Calculator
Calculate when to reorder inventory based on lead time, daily sales velocity, and demand variability. Prevent stockouts with safety stock levels.
Formula
What is a Reorder Point?
The reorder point (ROP) is the inventory level at which you should place a new order with your supplier to avoid running out of stock. It accounts for your average sales velocity and the time it takes to receive new inventory (lead time).
Running out of stock is one of the most expensive mistakes in e-commerce — you lose sales, ad spend is wasted, and your search rankings on Amazon and Google can drop significantly.
Understanding Safety Stock
Safety stock is the extra buffer inventory you keep to protect against unexpected demand spikes or supplier delays. Without safety stock, any variation in sales or lead time puts you at risk of a stockout.
- Conservative (low risk): 2-3 weeks of average sales as safety stock
- Moderate: 1-2 weeks of average sales
- Aggressive (lean): 3-7 days of average sales
Products with unpredictable demand or long lead times need more safety stock. Fast-selling, stable products can run leaner.
How Lead Time Affects Reorder Points
Lead time is the total time from placing a purchase order to having inventory ready to sell:
- Production time: 7-30 days depending on product complexity
- Shipping time: Sea freight (25-45 days), air freight (5-10 days), express (3-5 days)
- Customs clearance: 2-7 days depending on country and product
- Receiving & prep: 1-3 days to inspect, label, and shelve inventory
Always use your worst-case lead time for reorder point calculations to avoid stockouts.