Free Reorder Point Calculator

Calculate exactly when you need to order more stock. Eliminate guesswork, prevent stockouts, and stop tying up cash in excess inventory.

Calculate Variables

1. Basic Variables (Required)

How many units do you sell per day on average?

How many days does it take for a new order to arrive?

2. Safety Stock (Optional)

Enter your known safety stock, OR enter maximums below to calculate it automatically.

Or Calculate It

Your Reorder Point

0

When your stock hits this number, reorder immediately.

Lead Time Demand

0

Units needed while waiting for shipment

Safety Stock

0

Emergency buffer units

The High Cost of Guessing Your Inventory

Many retailers manage inventory by walking through the warehouse and eye-balling what looks "low." But what exactly does "low" mean? If a product sells 50 units a day and takes a week to arrive from the supplier, having 200 left on the shelf looks like a lot—but you will run out before the new shipment arrives.

This results in the dreaded Stockout: lost sales, frustrated customers migrating to competitors, and damaged search rankings on marketplaces like Amazon. Even worse is Overstocking, where cash is trapped sitting on shelves as dead inventory, silently killing your cash flow.

Understanding the Formula Variables

Average Daily Sales

Calculate this over a 30 to 90-day period. (Total Units Sold / Days in Period). Exclude days where you were out of stock, as they skew your average downward.

Lead Time (in Days)

The total days from when you hit "send" on the purchase order to when the products are received, unpacked, and ready to sell on your shelf.

Safety Stock

The buffer. Because suppliers are sometimes late, and sometimes a viral TikTok video causes a massive spike in unexpected sales over the weekend.

FAQ

Does this formula work for seasonal items?

Yes, but you must adjust your "Average Daily Sales" variable to reflect the season you are entering, not your yearly average. If you sell swimsuits, use last June's average daily sales to calculate your May order.

Can I just set safety stock to zero if my supplier is fast?

It's risky. Even next-day delivery can fail due to weather, system outages, or your supplier running out of stock themselves. Always maintain a small buffer.

How often should I recalculate my ROP?

For fast-moving products: monthly. For standard products: quarterly. E-commerce trends shift rapidly, and last year's reorder point might cause a stockout today.

Stop managing spreadsheets. Connect the dots.

Wiseventory's smart inventory system automatically tracks your daily sales, learns your supplier lead times, and alerts you the exact moment you need to reorder.

Frequently Asked Questions

What is a reorder point and why does it matter?

A reorder point (ROP) is the minimum stock level at which you should place a new purchase order to avoid running out of a product before the new stock arrives. Running out of stock means lost sales and unhappy customers; ordering too early ties up capital in excess inventory. Calculating the correct reorder point for each product helps you maintain just enough stock to meet demand during the supplier lead time, optimising both cash flow and customer satisfaction.

What is the formula for calculating reorder point?

The standard reorder point formula is: Reorder Point = (Average Daily Sales × Lead Time in Days) + Safety Stock. Average daily sales is the number of units you sell per day on average. Lead time is the number of days between placing an order and receiving the stock. Safety stock is a buffer quantity to cover unexpected demand spikes or supplier delays. The calculator on this page uses this formula and adds the safety stock calculation automatically based on your inputs.

How do I find my average daily sales for a product?

Divide your total sales quantity for a product over a period by the number of days in that period. For example, if you sold 300 units of a product in the last 30 days, your average daily sales is 10 units per day. For products with seasonal demand, use a shorter recent period that reflects current buying patterns rather than a full year average. Wiseventory's sales reports can give you this data automatically for every product in your inventory.

What is safety stock and how much should I keep?

Safety stock is extra inventory held as a buffer against unexpected demand increases or supplier delivery delays. The amount depends on how variable your sales are and how reliable your supplier is. A common formula is: Safety Stock = Z-score × Standard Deviation of Daily Sales × Square Root of Lead Time, where the Z-score reflects your desired service level (typically 1.65 for 95% service level). For small businesses without statistical data, keeping 5-10 days of sales as safety stock is a practical starting point.

Can Wiseventory automatically alert me when stock hits the reorder point?

Yes. In the Wiseventory billing platform, you can set a reorder point for each product in your inventory. When the stock level falls to or below the reorder point, Wiseventory automatically generates a low-stock alert, notifying you that it's time to place a new order with your supplier. This eliminates the need to manually monitor stock levels and ensures you never miss a reorder trigger, even during your busiest sales periods.