Reorder point and safety stock calculator
Calculate when to reorder inventory, your safety stock, and a suggested purchase quantity rounded to supplier packs. Free, with no signup.
Plan your next restock
Start with the example values or enter figures for one product. Your inputs stay in this browser.
How to calculate a reorder point
Reorder point = average daily sales × supplier lead time + safety stock. This calculator sets safety stock to daily sales × your chosen buffer days, rounded up to whole units. It is a simple days-of-cover method, not a statistical service-level forecast.
A worked example
At 5 units sold per day, a 14-day lead time consumes 70 units. A 7-day buffer adds 35 units, giving a reorder point of 105. With 90 on hand, no incoming stock, and 10 committed, your inventory position is 80: it is time to reorder.
Covering another 14 days between reviews gives a target of 175 units. The shortfall is 95 units; buying in packs of 12 rounds the suggested order to 96 units.
Why count incoming stock and customer commitments?
Inventory position is on hand + confirmed incoming stock − commitments. Counting confirmed orders helps avoid ordering the same stock twice. Incoming units are not included in the available-stock cover figure because they are not here yet.
When should I adjust the buffer?
Review it when supplier delays, promotions, or seasonality change. The model assumes steady average demand and does not schedule individual deliveries. A stockout warning can appear even with a healthy inventory position if physical stock will run out before the assumed lead time.
Formula reference: Shopify’s guide to safety stock and reorder points.
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