Reorder Point Calculator
This reorder point calculator finds the inventory level at which you should place your next order so stock arrives before you run out. Enter your average daily demand, supplier lead time, and safety stock, and it instantly returns your reorder point (ROP) using the standard formula.
It is built for anyone who manages physical stock — ecommerce sellers, retailers, warehouse and purchasing teams, and operations students learning inventory planning. A Basic mode lets you type a safety stock figure directly, while an Advanced mode derives safety stock from your peak usage and worst-case lead time.
How to Calculate Your Reorder Point
Choose Basic or Advanced
Start in Basic mode to enter your own safety stock, or switch to Advanced mode to have safety stock calculated for you from peak usage and the longest lead time.
Enter demand and lead time
Type or drag the sliders for Average Daily Demand (units/day) and Lead Time (days) — the gap between placing an order and receiving it.
Set safety stock
In Basic mode, enter your Safety Stock buffer directly. In Advanced mode, enter your Maximum Daily Usage and Maximum Lead Time and the buffer is computed for you.
Read your reorder point
The Reorder Point updates instantly, alongside lead time demand, safety stock, and annual demand. Open Formula Breakdown to see every value plugged in.
Features
Basic and Advanced Modes
Enter safety stock directly in Basic mode, or let Advanced mode calculate it from your maximum daily usage and longest lead time.
Real-Time Sliders
Type a value or drag the slider for any input and the results recalculate instantly — no calculate button to press.
Automatic Safety Stock
Advanced mode derives your buffer from supply and demand variability: (Max Daily Usage × Max Lead Time) − (Avg Demand × Avg Lead Time).
Lead Time and Annual Demand
Alongside the reorder point you also see lead time demand, the safety stock used, and projected annual demand at your daily average.
Formula Breakdown
Expand a step-by-step view showing every variable with its value. In Advanced mode it also shows how safety stock is derived.
Volume Presets
Load Low, Medium, or High Volume presets to benchmark typical inventory scenarios or explore the calculator quickly.
Frequently Asked Questions
What is a reorder point?
A reorder point (ROP) is the inventory level that triggers a new purchase order. When your stock drops to this number, it is time to order more so the replenishment arrives before you run out and risk a stockout.
What is the reorder point formula?
The formula is Reorder Point = (Average Daily Demand × Lead Time) + Safety Stock. The first part is your lead time demand — the units you expect to sell while waiting for delivery — and safety stock is the buffer added on top.
How do you calculate reorder point with safety stock?
Multiply your average daily demand by the lead time to get lead time demand, then add your safety stock. For example, 50 units/day over a 7-day lead time is 350 units; with 50 units of safety stock the reorder point is 400. Use Basic mode to enter the buffer, or Advanced mode to compute it automatically.
What is the difference between reorder point and safety stock?
Safety stock is the extra buffer you hold against demand spikes or supplier delays. The reorder point is larger: it adds that buffer on top of the demand you expect during the lead time, so it is the actual stock level at which you reorder.
How does lead time affect the reorder point?
Lead time is a direct multiplier on demand, so a longer lead time raises the reorder point. If a supplier slows down, you need more units on hand before reordering to cover the extra waiting days. Recalculate whenever your typical lead time changes.
When should I use Advanced mode?
Use Advanced mode when you have data on your peak demand days and longest supplier lead times. It sets safety stock to the difference between your worst case and your average, giving a data-driven buffer. If maximum usage times maximum lead time equals average demand times average lead time, the buffer is zero — a sign of very stable supply and demand.
How do I find my average daily demand?
Divide total units sold over a period by the number of days in it. Selling 1,500 units in 30 days is 50 units/day. Use at least 3 to 6 months of data for a reliable average, and review your reorder point before each peak season if your business is seasonal.
No comments yet. Be the first to comment!