Reorder Point Calculator (with EOQ)

Enter your average daily demand, supplier lead time, and safety stock to get the exact stock level at which you should reorder - for up to 20 SKUs at once, with an EOQ calculator built in and CSV export. Everything runs in your browser: no signup, no email capture, instant results.

What is a reorder point?

A reorder point is the stock level that triggers a new purchase order. When your on-hand quantity falls to that number, it is time to reorder. The formula is average daily demand multiplied by supplier lead time, plus safety stock, so you can cover sales until the new stock arrives.

Why it matters: order too late and you stock out while the replenishment is still in transit; order too early and you tie up cash in inventory you do not need yet. A reorder point turns "when should I order?" from a judgment call into a rule you can check against your stock report in seconds - or automate entirely.

The reorder point formula, explained

Reorder point = (average daily demand × lead time in days) + safety stock.

Worked example, the same one prefilled in the calculator above: you sell 20 units a day, your supplier takes 7 days to deliver, and you hold 30 units of safety stock. Demand during lead time is 20 × 7 = 140 units, plus the 30-unit buffer gives a reorder point of 170 units. When stock hits 170, you place the order; the 140 covers expected sales while you wait, and the 30 covers the surprises.

One detail that trips people up: always round the reorder point up. It is a trigger, not an order size. If the math says 169.2 and you round down to 169, you place every order one unit's worth of demand too late. The calculator above rounds up automatically.

How to find your average daily demand and lead time

For demand, take total units sold over the last 90 days and divide by 90. Ninety days smooths out weekly noise without reaching so far back that old demand patterns pollute the number; for strongly seasonal products, use the same season last year instead. If you sell through QuickBooks Online, the sales-by-product report gives you the unit counts directly - our guide to QuickBooks inventory for manufacturers covers where those reports fall short for production businesses. Count all channels: wholesale, online, and units consumed internally as components.

For lead time, measure door to door: the date you placed the purchase order to the date stock was received and put away, including weekends. Average your last three to five real purchase orders rather than trusting the supplier's quoted time - quoted and actual lead times drift apart quietly. If one PO was an outlier (a port strike, a factory shutdown), note it, but let safety stock absorb that kind of variation instead of inflating the average.

Safety stock: the buffer most people guess wrong

Safety stock is the one input in the formula that most businesses guess - a round number that felt safe at the time. Guessing high ties up cash on every single SKU; guessing low means the reorder point fires too late whenever demand spikes or a delivery slips. The right buffer comes from your actual variation: a simple max-min calculation if you know your worst-case demand and lead time, or a Z-score method if you can pull a standard deviation from your sales history.

Both take about a minute with our free safety stock calculator. Run your numbers there, then paste the result into the safety stock field above - the reorder point updates instantly.

EOQ calculator: how much to order

The reorder point tells you when to order; the economic order quantity (EOQ) tells you how much. EOQ balances two opposing costs - the fixed cost of placing each order and the annual cost of holding a unit in stock - and finds the order size that minimizes their sum. The formula is the square root of (2 × D × S ÷ H), where D is annual demand in units, S is the cost of placing one order, and H is the annual holding cost per unit.

Worked example: with annual demand of 12,000 units, $50 per order, and $2 per unit per year to hold, EOQ = sqrt(2 × 12,000 × 50 ÷ 2) = sqrt(600,000) ≈ 775 units per order - about 15 orders a year, one every three and a half weeks. If you do not know your holding cost, the common rule of thumb is 20-30% of unit cost per year, covering storage, insurance, shrinkage, and the cost of the cash itself; the calculator's "I don't know my holding cost" option applies exactly that. Because the EOQ section sits under the same calculator, you can size the order and set the trigger in one place instead of juggling two tools.

Common mistakes when setting reorder points

• Using a gut-feel number instead of measured demand. "Reorder at 100" usually means someone once ran out at 80. Measure the demand; the formula is only as good as its inputs.
• Using the supplier's quoted lead time. Quoted times are marketing. Use the actual dates from your last few purchase orders.
• Rounding down. The reorder point is a trigger - rounding down fires it late. Round up, always.
• Setting it once and never revisiting. Demand drifts, suppliers change, seasons turn. Recheck your inputs quarterly, or after any supplier change.
• Skipping safety stock - or double counting it. Leaving it at zero means any hiccup becomes a stockout. But if you already padded your "lead time" to be pessimistic, adding a big buffer on top double counts the same risk.

Calculating reorder points for multiple SKUs

One SKU is easy. Twenty is where spreadsheets start to hurt: each item has its own demand rate, its own supplier lead time, its own buffer, and all of them drift. The calculator above handles up to 20 items in one pass and exports the results to CSV, so you can run your whole catalog quarterly and paste the fresh numbers wherever they live.

The harder problem is comparing those reorder points against live stock every day. That is what Evenbatch is built for: it tracks on-hand quantities per item in real time, keeps your reorder points alongside them, and shows you what has fallen below its trigger - including raw materials consumed by production, where usage comes from builds rather than sales. If your components live on a bill of materials in QuickBooks, demand for them is driven by what you manufacture, and that is exactly the demand a sales report will not show you.

Keep exploring: free inventory tools

This calculator is one of a set of free, no-signup tools we built for small manufacturers. Size your buffer with the safety stock calculator, cost out your recipes with the bill of materials template and cost calculator, and check expiration dates and the 2/3 rule with the shelf life calculator. Each one runs entirely in your browser and exports to CSV.

And when you are ready to stop copying numbers between spreadsheets, start a free Evenbatch trial and keep reorder points, BOMs, and lot tracking in one place, synced with QuickBooks Online.

See something outdated or incorrect on this page? Email support@evenbatch.com and we will correct it within 48 hours. Last updated: July 18, 2026.