Reorder Calculator – Easy Reorder Point & Safety Stock in 3 Steps
Supply Chain Reorder Point Calculator
Free reorder calculator – determine exactly when to replenish your inventory by calculating Lead Time Demand, Safety Stock, and your optimal Reorder Point (ROP).
Demand & Lead Time Variables
Optimal Reorder Point (ROP)
Reorder inventory when stock falls to this unit level.
Safety Stock Required
Buffer units against delays
Lead Time Demand (LTD)
Units sold during lead time
Max Risk Exposure
Max demand × Max lead time
Supply Chain Formulas & Best Practices
Key Calculations
- Lead Time Demand (LTD):
Average Daily Demand × Average Lead Time - Safety Stock:
(Max Daily Demand × Max Lead Time) - LTD - Reorder Point (ROP):
Lead Time Demand + Safety Stock
Inventory Optimization Strategies
- Avoid Stockouts: Your ROP triggers a new order. If you wait until inventory drops below this number, you risk running out of stock during production delays.
- Reduce Holding Costs: Lowering your maximum lead times through better supplier negotiations directly reduces the amount of Safety Stock you need to hold, freeing up capital.
- Dynamic Recalculation: Demand fluctuates seasonally. Recalculate your ROP quarterly for your e-commerce website or production facility.
Use this free reorder calculator to know exactly when to place your next purchase order – before you run out of stock.
Quick answer
The reorder point (ROP) = Lead Time Demand + Safety Stock. Lead time demand is average daily demand × average lead time, and safety stock is (max daily demand × max lead time) − lead time demand. Example: selling 50 units a day on average (80 max) with a 10-day lead time (15 max) gives LTD 500, safety stock 700 and a reorder point of 1,200 units.
Table of Contents
Order too late and you run out of stock while the next shipment is still on its way. Order too early and cash sits on the shelf as excess inventory. The reorder point is the stock level that tells you the right moment to buy again.
Our free reorder calculator turns four numbers – average and maximum daily demand, and average and maximum lead time – into lead time demand, safety stock and a clear reorder point. It works for e-commerce stores, retail shops, restaurants and manufacturers.
Reorder Point Formulas Used by the Calculator
| Metric | Formula | Example (50/80 units, 10/15 days) |
|---|---|---|
| Lead Time Demand (LTD) | Avg daily demand × Avg lead time | 50 × 10 = 500 |
| Max Risk Exposure | Max daily demand × Max lead time | 80 × 15 = 1,200 |
| Safety Stock | Max risk exposure − LTD | 1,200 − 500 = 700 |
| Reorder Point (ROP) | LTD + Safety stock | 500 + 700 = 1,200 |
This is the “max-min” safety stock method. It is simple, easy to explain to a team, and protects you against the worst combination of high demand and slow delivery you have seen. Businesses with lots of sales data may later move to a statistical method based on standard deviation and a target service level.
What is lead time?
Lead time is the total time from placing an order to having stock ready to sell: supplier production, shipping, customs clearance and receiving. Use real numbers from past orders, not the supplier’s best-case promise.
How to Use the Reorder Calculator
Find your reorder point in three steps.
Step 1: Enter Demand and Lead Time
Type your Average Daily Demand and Maximum Daily Demand in units, then your Average Lead Time and Maximum Lead Time in days. For example: 50, 80, 10 and 15. Click Calculate Reorder Point.
Step 2: Read Your Reorder Point and Safety Stock
The tool shows the Optimal Reorder Point (1,200 units in the example) with a plain instruction – place a new order when stock drops to that level. Below it you see Safety Stock Required (700), Lead Time Demand (500) and Max Risk Exposure (1,200).
Step 3: Check the Formulas and Strategies
Scroll to Supply Chain Formulas & Best Practices to see how each number is calculated and how to reduce stock levels. Use Export Calculations (JSON) to save the results, or Clear Inputs to check another product.
How to Use Your Reorder Point in Practice
- Set the reorder point as a low-stock alert in your inventory or e-commerce system (Shopify, WooCommerce, ERP).
- When stock reaches the ROP, place an order big enough to cover demand until the following delivery.
- Track actual lead times for each supplier and update the inputs.
- Recalculate every quarter, and before peak seasons like Ramadan, Eid, Black Friday or Christmas.
Reorder Calculator Examples by Business Type
| Business | Avg / Max daily demand | Avg / Max lead time | Reorder point |
|---|---|---|---|
| Online store (phone cases) | 30 / 50 units | 12 / 20 days | 1,000 units |
| Coffee shop (milk, litres) | 40 / 60 | 2 / 3 days | 180 litres |
| Small factory (bolts) | 500 / 700 | 7 / 10 days | 7,000 units |
Each row uses the same reorder calculator formulas: for the online store, LTD = 30 × 12 = 360, max exposure = 50 × 20 = 1,000, safety stock = 640, so the reorder point is 1,000 units. Fast-moving, short lead-time items like fresh milk need a low reorder point but frequent orders, while imported goods with long, unpredictable lead times need a much bigger buffer.
Reorder point vs reorder quantity
The reorder point tells you when to order; the order quantity tells you how much. A common starting point is to order enough to cover demand until the next planned delivery, or to use the Economic Order Quantity (EOQ) if ordering and holding costs are known.
Ways to Lower Safety Stock (and Free Up Cash)
- Shorten lead times by choosing closer suppliers or faster shipping.
- Reduce lead time variability with reliable suppliers and clean customs paperwork – see our Customs Brokerage Fee Checklist.
- Improve forecasting using past sales by season.
- Split products by value (ABC analysis) and hold more safety stock only for best-sellers.
Need to plan cash for the reorder? Try the Budget Calculator or measure ad returns with the ROAS Calculator.
Frequently Asked Questions
How do you calculate a reorder point?
Reorder point = lead time demand + safety stock. Lead time demand is average daily demand × average lead time.
How is safety stock calculated here?
Safety stock = (maximum daily demand × maximum lead time) − lead time demand.
What is a good reorder point?
One that covers expected demand during lead time plus a buffer for delays and sales spikes. The calculator gives this number from your own data.
How often should I recalculate my reorder point?
At least every quarter, and whenever demand or supplier lead times change noticeably.
Does the reorder calculator work for e-commerce?
Yes. It works for any product with daily sales and a supplier lead time – online stores, retail, restaurants and factories.
Is the reorder calculator free?
Yes. It is free, needs no sign-up and runs in your browser.