Find the exact stock level to reorder at — so you never run out and never tie up more cash than you need to.
Your reorder point is the on-hand stock level that tells you to place a new order today. Hit that number for any SKU and you place the PO — new stock arrives just before you run out. Calculated as average daily sales × supplier lead time, plus a safety-stock buffer that covers a bad week of sales or a slipped delivery.
Example: You sell 8 bags of coffee per day. Your supplier takes 5 days to deliver. That means you need at least 40 bags on hand when you order — otherwise you run out before the delivery arrives. Add a 7-day buffer and your reorder point is 96 bags. This calculator finds that number for you.
Grab these three numbers — they take less than 5 minutes to find.
Your average daily sales for this product
Open your POS or sales dashboard → filter by the product → look at the last 30 days → divide total units sold by 30. Even a rough number is fine.
Your supplier's lead time in days
This is how many days it takes from when you place the order to when the stock arrives on your shelf. Check a recent invoice date vs. delivery date, or just ask your supplier rep.
How many buffer days you want
Extra days of stock to protect you if your supplier is late or demand spikes. If you're not sure, start with 7. Bump it up if your supplier is often delayed.
Check your last 30–90 days of sales.
Order placed to stock in hand.
Extra cushion. 7–14 days is common.
Add this to see how many days until you hit your reorder point.
Try an example
Your reorder point (ROP) is the inventory level at which you should place a new order. It's the answer to "when do I reorder?" — not "how much do I order?" Hit your ROP, place the PO; new stock arrives just before you run out.
The formula: Reorder Point = (Average Daily Sales × Lead Time in Days) + Safety Stock. Average daily sales is how fast you sell. Lead time is how long your supplier takes from PO to delivery. Safety stock is your buffer for the days when sales spike or your supplier slips.
Real example: you sell 20 candles a day on average. Your supplier needs 15 days to deliver. On your busiest week, you sold 35 a day. Your worst-case lead time was 22 days. Safety stock = (35 × 22) − (20 × 15) = 470 units. ROP = (20 × 15) + 470 = 770 units. When candle inventory drops to 770, you reorder.
Sales velocity changes weekly. Supplier lead times drift. Seasons shift demand by 200–300% on the same SKU. A static ROP on a spreadsheet — calculated once and never updated — is the single biggest reason small shops oscillate between stockouts and dead stock. By the time you notice, you've lost a month of sales or buried 90 days of cash.
ReUp recalculates your ROP every day, per SKU, across Shopify, Square, and WooCommerce. It detects seasonal patterns from your own sales history, learns each supplier's real lead time over time, and adjusts safety stock based on a service level you choose (95%, 97%, 99%). When a SKU hits its reorder point, ReUp drafts the PO and waits for your one-click approval.
The formula
ROP = Daily Sales × (Lead Time + Buffer Days)
Daily Sales
How many units you sell per day on average. Use a 30–90 day window — long enough to smooth out noise, short enough to be current.
Lead Time
The number of days from when you place an order to when it's on your shelf. Get this from your supplier's terms or measure it from your last few orders.
Buffer Days
Extra days of stock to keep as a cushion against late deliveries or demand spikes. 7 days is a reasonable starting point for most small businesses. Increase it if your supplier is unreliable.
When to recalculate
Recalculate every 90 days minimum, and 30–60 days before any known demand spike — Q4, holiday seasons, or viral product moments. A static ROP is the #1 cause of unnecessary stockouts.
What is a reorder point in plain language?
Your reorder point is the on-hand stock level that tells you to place a new order today. Calculated as average daily sales × supplier lead time, plus a safety-stock buffer. Hit that number, place the PO, and new stock arrives just before you run out — without burying cash in inventory you do not need yet.
How is the reorder point formula different from EOQ?
Reorder point answers when to order. Economic Order Quantity (EOQ) answers how much to order. They are different decisions and most small retailers only need ROP done well. EOQ matters when fixed ordering costs are high and stock-holding costs are also high — typically larger businesses with formal warehousing. ROP works for everyone.
How often should I recalculate my reorder points?
Every 90 days at minimum. Recalculate sooner — 30 to 60 days in advance — for any known demand spike, Q4 retail surge, viral product moment, or supplier holiday. Static reorder points kept in a spreadsheet are the single biggest cause of unnecessary stockouts in small retail. Velocity drifts; lead times drift; the ROP has to drift with them.
What lead time should I use — quoted or actual?
Actual. Pull the last five to ten purchase orders for that supplier and use the average elapsed days from PO sent to stock received. Real lead times are usually 20 to 40 percent longer than the supplier quote. If you use the quoted number, your reorder point is too low and you will stock out the first time the supplier slips.
How much safety stock should I carry?
Safety Stock = (Max Daily Sales × Max Lead Time) − (Average Daily Sales × Average Lead Time). This formula sets a buffer that covers the worst recent week of sales and the worst recent lead-time slip. A 7-day fixed buffer works as a starting point if you do not have variance data; the formula version replaces gut-feel with the actual range you have already lived through.
Does Shopify, Square, or WooCommerce calculate reorder points for me?
No. Shopify tracks stock counts and surfaces low-inventory alerts but does not compute a reorder point. Square exposes stock alerts only on Square for Retail Plus. WooCommerce tracks stock thresholds via plugins. None of the three calculate a velocity-aware reorder point that adjusts as your sales pace shifts. A third-party tool or the formula above is the realistic path.
The other free calculators in the same family. Use any one without an account.
Stockout Cost Calculator
The full cost of running out — revenue, freight, churn.
MOQ Break-Even Calculator
Whether a supplier’s minimum order is actually profitable.
Recipe COGS Calculator
Real cost per unit for makers, batch by batch.
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Move off Shopify Stocky before the August 31, 2026 sunset.
Last updated: June 2026
ReUp does this automatically.
It watches your sales, sets the reorder point, and drafts the order — you just approve.
