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Reorder point calculator

Your reorder point is the stock level at which you should place a new purchase order — early enough that the delivery arrives before you sell out, late enough that you're not sitting on cash you didn't need to spend. Enter your numbers; everything updates as you type.

Sales per day (units)Average over the last 30–90 daysSupplier lead time (days)Order placed → goods on your shelfSafety stock (days)Buffer for late deliveries & sales spikesCoverage target (days)How long each order should lastStock on hand (units)Available right nowIncoming (units)Already on open purchase orders

Reorder point — order when stock hits this level42 units

Days of stock left at current sales pace20 days

Inventory position (on hand + incoming)40 units

Order now — suggested quantity62 units

The formula

Reorder point = daily sales × (lead time + safety stock days)

The logic: from the moment you order, you keep selling for the whole lead time — that's daily sales × lead time units gone before the box arrives. Safety stock adds a buffer on top, because suppliers run late and demand spikes. When your inventory position (stock on hand plus anything already ordered) drops to that number, it's time to order.

The suggested quantity goes one step further: daily sales × (lead time + safety + coverage) − inventory position. That tops you up to enough stock to survive the wait and last your chosen coverage period after arrival — without double-ordering what's already on a PO.

Worked example

You sell 2 units a day, your supplier takes 14 days, and you keep 7 days of safety stock. Reorder point = 2 × (14 + 7) = 42 units. With 40 on hand and nothing incoming you're already below it: ordering 2 × (14 + 7 + 30) − 40 = 62 units covers the lead time and a month of selling after delivery.

Three mistakes that cause stockouts anyway

Using last year's velocity. Sales pace drifts; recompute from the last 30–90 days, and weight recent weeks more heavily.
Forgetting incoming stock. Compare the reorder point against on-hand plus open POs, or you'll double-order every cycle.
Checking manually. A spreadsheet is correct exactly once: the day you fill it in. Per-SKU reorder points only work when something recalculates them daily.

Do this automatically for every SKU

This calculator is the math for one product. OrderPoint runs it across your whole Shopify catalog from live sales data — flags what needs ordering, builds the purchase orders per supplier, emails them as PDFs, and updates Shopify stock when you receive. $19/month flat, 14-day free trial. If you're migrating from Stocky, start with the migration checklist or the alternatives comparison.

Written by the OrderPoint team — the same formula (with weighted recent-sales velocity) powers the app's reorder suggestions.