Reorder Point Calculator Template (Excel Spreadsheet)

A reorder point calculator tells you when to place your next purchase order. Plug in your demand rate, supplier lead time, and safety stock buffer, and the spreadsheet flags every SKU that needs replenishment right now.

A 2023 IHL Group report puts stockout costs at $1.75 trillion globally per year. A properly calibrated reorder point is the single most effective way to prevent them. This is a fillable worksheet template, not an on-page interactive calculator.

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The math follows the standard reorder point model and maps directly to the reorder point formula walkthrough.

Why reorder points matter

Stockouts cost retailers $1.75 trillion globally per year

Running out of stock is expensive. Beyond the lost sale, stockouts damage customer trust and search ranking on platforms like Shopify and Amazon. Harvard Business Review found that 21-43% of customers who encounter a stockout buy from a competitor instead.

Setting a reorder point for every active SKU means you catch replenishment needs before inventory drops to zero, not after.

Scenario	Without reorder point	With reorder point
Stockout frequency	Reactive ordering; frequent gaps	Proactive ordering; rare gaps
Order timing	Based on gut feel or calendar	Based on actual demand and lead time
Safety stock usage	Inconsistent or absent	Calculated buffer per SKU
Working capital efficiency	Over-ordering on some, under on others	Right-sized per SKU velocity

Input table: 6 columns per SKU

Column	Type	Purpose
SKU	Manual	Product variant identifier
Avg daily demand	Manual	Average units sold per day over the past 30 days
Lead time (days)	Manual	Average supplier delivery time from PO to receipt
Safety stock	Manual	Buffer units for demand variability and supplier delays
Current on-hand	Manual	Units physically in stock right now
Current inbound	Manual	Units on open POs expected to arrive

Pull demand from the past 30 days of actual sales. For seasonal SKUs, use the same 30-day window from last year if you have it. 90-day averages smooth out short spikes but can mask recent demand shifts, so 30 days is the better default.

3 formulas

How do you calculate a reorder point?

Reorder point, the stock level where you cut a new PO:

reorder point = (avg daily demand x lead time) + safety stock

Available to promise, total stock you can actually sell, including inbound:

available to promise = on-hand + inbound

Reorder flag, a simple yes/no that tells purchasing to act:

reorder now? = yes if available to promise is at or below reorder point

The flag fires when ATP (not just on-hand) drops to or below the reorder point. Counting inbound stock keeps you from placing a duplicate PO when one is already on the water.

Output table: 3 columns per SKU

Column	Formula	Example
Reorder point	(avg daily demand x lead time) + safety stock	170 units
Available to promise	on-hand + inbound	150 units
Reorder now?	Yes if ATP is at or below reorder point	Yes

Walk through it: a SKU selling 10 units per day with a 12-day lead time and 50-unit safety stock lands at a reorder point of 170. On-hand is 100, inbound is 50, so ATP is 150. That is below the 170 threshold, and the flag fires.

Worked examples by SKU velocity

Different demand levels produce very different reorder points. Here are 3 examples using the same formula:

SKU	Daily demand	Lead time	Safety stock	Reorder point	On-hand	Inbound	ATP	Reorder?
Fast mover	25 units	7 days	80 units	255	200	40	240	Yes
Mid velocity	8 units	14 days	30 units	142	160	0	160	No
Slow mover	1 unit	21 days	10 units	31	35	0	35	No

The fast mover has an ATP of 240, which is below its 255 reorder point, so it triggers a reorder. The mid-velocity SKU sits comfortably above its threshold. The slow mover is close but not yet flagged.

Refresh guidelines

How often should you update reorder points?

Keeping your calculator accurate requires regular input updates:

• Demand: Recalculate avg daily demand every month from the last 30 days of actual sales
• Lead time: Refresh quarterly or whenever you switch suppliers. Use the average of your last 3-5 deliveries. The number on the supplier’s quote sheet is almost always optimistic.
• Safety stock: Recalculate with the safety stock formula any time demand or lead time variability shifts. Safety stock is a buffer against forecast error — treat it as a living number, not a set-and-forget constant.
• On-hand and inbound: Update daily, or at least before every reorder review

Stale inputs wreck your reorder points. If you are still running on last quarter’s demand numbers, you will either over-order (tying up cash) or under-order (eating stockouts). A 2022 Gartner supply chain survey found that 57% of companies named demand sensing accuracy as their top inventory planning challenge.

Check stockout trends with warehouse KPIs that actually matter to validate whether your reorder points are actually doing their job.

When to move beyond a spreadsheet

A spreadsheet reorder calculator works well for operations with under 100 active SKUs and 1-2 suppliers. Past that, manual refresh becomes the bottleneck. Signs you have outgrown the spreadsheet:

• You are refreshing demand data for more than 200 SKUs monthly
• Multiple team members update the same file, creating version conflicts
• Lead times vary across 5+ suppliers, each with different refresh cadences
• You miss reorder triggers because on-hand data was stale

Small business inventory tracking software automates reorder point monitoring by pulling live on-hand counts and inbound PO data. Your reorder flags update in real time without manual spreadsheet refreshes.

Quick Reference

• Input table has 6 columns per SKU: SKU, avg daily demand, lead time, safety stock, on-hand, inbound
• Output table has 3 columns per SKU: reorder point, available to promise, reorder flag
• Uses 3 formulas: reorder point, available to promise, and reorder flag
• Refresh demand data every 30 days, lead time data quarterly
• Reorder flag includes inbound stock to prevent double-ordering
• Stockouts cost retailers an estimated $1.75 trillion globally per year (IHL Group, 2023)
• 21% to 43% of customers buy from competitors after encountering a stockout (HBR)
• 57% of companies cite demand sensing accuracy as their top inventory planning challenge (Gartner, 2022)

Input	Update frequency	Data source
Avg daily demand	Monthly (30-day rolling)	Sales / order data
Lead time	Quarterly	Last 3 to 5 PO receipts
Safety stock	When variability changes	Safety stock formula
On-hand	Daily	Inventory system or count
Inbound	Daily	Open purchase orders