Reorder Point Calculator
The stock level that should trigger your next purchase order
Updated 2026-09-09
- Safety stock
- 36 units
- Reorder at
- 120 units
- Days of cover at reorder
- 10.0 days
When stock hits the reorder point, place the order. Widen the safety buffer for suppliers that miss dates or products with spiky demand.
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Stockouts cost the sale and often the customer; overstock ties up cash you needed elsewhere. The reorder point sits between the two: the stock level at which you place the next order so the delivery lands just before you run dry.
The formula
Reorder point = (average daily sales × lead time in days) + safety stock. Safety stock here is expressed as extra days of cover, so a product selling 12 units a day with a 7-day lead time and a 3-day buffer reorders at (12 × 7) + (12 × 3) = 120 units.
Days of cover is the quick method. To size the buffer to a target service level from how much your demand and your supplier's delivery times actually vary, use the safety stock calculator and enter its reorder point here.
Lead time means the full elapsed time from you pressing send to the goods being sellable on your shelf — including weekends, customs, and the afternoon it takes to unpack and label.
Choosing a safety buffer that fits the product
The buffer absorbs two kinds of surprise: demand spiking and the supplier arriving late.
- Reliable supplier, steady demand: 2–3 days is usually enough
- Overseas or seasonal supplier: 7–14 days, more before a known peak
- Best sellers and anything a customer will not wait for: widen the buffer
- Perishable or fast-obsoleting stock: keep it tight and reorder more often
Getting the daily sales figure right
Use a recent period that reflects normal trading — typically the last 30 to 90 days — and exclude one-off bulk orders that would inflate the average. For seasonal lines, use the same period last year rather than the current quiet month, then recheck as the season starts.
If a product sells fewer than a handful of units a week, the average is noisy. For those, review the stock level manually rather than relying on a formula.
Order quantity is a separate decision
The reorder point tells you when to order, not how much. That quantity depends on supplier minimums, price breaks, shelf and storage space, and how much cash you can leave sitting in stock. A common approach is to order enough for four to eight weeks of sales, then adjust once you see how quickly it actually turns.
Automating the trigger
A reorder point only works if something watches it. Set the low-stock threshold on each product in ExpressBizTools to the number this calculator gives you, and the low-stock alert becomes your purchase-order prompt — no spreadsheet review required. Barcode-based stock counts keep the underlying numbers accurate enough for the alert to be trusted.
Keep the numbers in a spreadsheet
Ready-made Excel and Google Sheets templates that pick up where this calculator stops. One-off purchase, instant download.
Inventory Tracker & Stock Control Spreadsheet
150 SKUs, stock in/out log, automatic on-hand counts, reorder alerts, a reorder list and a dashboard.
Frequently asked questions
What is the difference between reorder point and safety stock?
Safety stock is the cushion held for surprises. The reorder point is that cushion plus the stock you will sell while waiting for the delivery to arrive.
How do I handle a supplier with unpredictable lead times?
Use their worst realistic lead time rather than their average, and widen the safety buffer. If the variance is extreme, splitting orders between two suppliers usually costs less than the stockouts.
Should every product have a reorder point?
Set them for your top-selling lines and anything with a long lead time. Slow sellers are better reviewed by eye during a periodic stock count.
How often should reorder points be updated?
Quarterly for most products, and before any seasonal peak. Any large shift in daily sales or supplier lead time should also trigger a review.
Related reading
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