# Reorder point calculator > Find the stock level that should trigger your next order. - Source: https://storestandards.com/tools/reorder-point-calculator/ - Kind: Calculator - Updated: 2026-08-15 - Author: Nia Chambers, Product, Store Standards --- ## The formula A reorder point is two things added together. ``` reorder point = (units sold a day × lead time in days) + safety stock ``` The first part covers what you will sell while you wait. The second covers the weeks when the shop is busy and the van is late at the same time. Both halves matter. Most stores get the first one right and skip the second. ## A worked example You sell twelve units a day. Your supplier takes fourteen days from order to shelf. You keep sixty units as a buffer. Twelve times fourteen is 168 units sold while you wait. Add the sixty unit buffer and your reorder point is 228. So when stock drops to 228, the order goes out. If everything runs normally you will still have sixty units left when the new pallet arrives. ## What a good number looks like The buffer is the part worth arguing about. A rough rule is that it should cover at least a fifth of your [lead time](https://storestandards.com/glossary/lead-time/) demand again. Below that, one late delivery empties the shelf. If you want the buffer worked out properly rather than guessed, use the [safety stock calculator](https://storestandards.com/tools/safety-stock-calculator/). It asks for your worst week and your slowest delivery, then gives you the gap between those and normal. Three things push a reorder point up: longer lead times, faster sales, and a supplier who misses dates. Only the last one is worth a conversation. ## Where this goes wrong The number is only as good as your stock count. If Shopify thinks you have 228 and the shelf has 190, the order goes out late whatever the maths says. That is the same problem the article on [stock counts drifting](https://storestandards.com/blog/why-shopify-stock-counts-drift/) is about, and it is worth fixing first. The other common mistake is using a peak month for daily sales. Do that and you carry the cost of Christmas stock all year. Use a normal month, then set a separate reorder point for the run up to a peak. ## What it asks for - **Units sold a day**: Average over a normal month, not your best week. - **Lead time in days**: Order placed to stock on the shelf. - **Safety stock in units**: The buffer you keep for a bad week. ## What it gives back - **Order when stock drops to** (units) - **Sold during the lead time** (units) - **Days of cover at this level** (days) ## Questions **What is a reorder point?** It is the stock level that tells you to buy more. When the shelf drops to that number, the order goes out. Set it right and the new delivery lands just as the old stock runs out. **Where do I find my daily sales in Shopify?** Reports, then Sales by product. Pick a normal month and divide the units sold by the days in it. Skip a month with a sale in it, because that number will set your buffer too high. **Should lead time include the weekend?** Yes. Count real days from placing the order to stock being ready to sell. That includes the days the box sat in goods in waiting to be booked in. **How often should I redo this?** Once a quarter, and after any supplier changes their delivery times. A reorder point set two years ago is describing a shop that no longer exists. **Can Shopify do this for me?** Shopify shows you what is low, but it does not work out the level for you. You set the number here and then use it as your own low stock alert.