Stock Reorder Point Calculator
Calculate the inventory level at which you should place a new order based on demand, lead time and safety stock.
Overview
The Stock Reorder Point Calculator helps you estimate when to place a new inventory order using average daily usage, supplier lead time and safety stock. It is useful for planning replenishment so you can keep enough stock available without ordering too early.
How it works
The calculator estimates how much stock you are likely to use during supplier lead time, then adds your safety stock buffer. The basic formula is reorder point = demand during lead time + safety stock. Demand during lead time is calculated from your average daily usage multiplied by the number of lead time days. Comparing your current stock to the reorder point helps estimate how close you are to needing a new order.
How to use this calculator
- 1Enter your average daily usage in units.
- 2Add the typical supplier lead time in days.
- 3Enter the safety stock you want to keep as a buffer.
- 4Input your current stock on hand.
- 5Review the reorder point and the estimated days until you should place the next order.
Example Calculation
Average Daily Usage
50
Lead Time
7
Safety Stock
100
Current Stock
500
Working Days per Week
7
Reorder Point
450 units
If you use 50 units per day, have a 7-day lead time and keep 100 units as safety stock, your reorder point is 450 units. With 500 units currently on hand, you are about 1 day above the reorder point.
Frequently asked questions
What does the stock reorder point mean?
It is the inventory level at which you should place a new order so incoming stock arrives before you run out.
How is reorder point calculated?
A common formula is demand during lead time plus safety stock. Demand during lead time is average daily usage multiplied by lead time in days.
Why is safety stock included?
Safety stock gives you a buffer against unexpected demand increases or supplier delays.
Can I use this calculator for any product?
Yes, it can be used for many stocked items as long as you have a reasonable estimate of usage, lead time and desired safety stock.
What if my demand changes by season?
If demand varies throughout the year, update your average usage and safety stock regularly to reflect current conditions.
What does a negative stock gap mean?
It means your current stock is already below the reorder point, so you may need to order immediately.
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Assumptions and warnings
Assumptions
- Demand is relatively stable over time.
- Lead time is entered as a typical average and does not account for extreme supplier delays.
- Safety stock is set separately by the user and reflects the desired buffer level.
- The calculation does not include seasonality, promotions, bulk orders or sudden demand spikes.