Free · Two safety stock methods

Reorder point and safety stock calculator

Know when to reorder: reorder point and safety stock from daily demand and supplier lead time.

  • Free, no signup
  • Stays in your browser
  • Sources named below

Your item

Units sold or used per day, on average.
From placing the order to having it on the shelf.
Safety stock method
Use STDEV on the daily sales of the last 30+ days.
The chance of not running out during the lead time.

Result

Enter the demand, lead time and the safety stock inputs. The reorder point appears here.

How it is calculated

The working

  • Reorder point = average daily demand x lead time in days + safety stock. When stock falls to this level, place the order.
  • Statistical safety stock = z x standard deviation of daily demand x square root of the lead time in days. The z value comes from the service level you want: 90% is 1.28, 95% is 1.64, 97.5% is 1.96, 99% is 2.33. It assumes demand varies day to day and lead time is steady.
  • Simple safety stock = (highest daily use x longest lead time) - (average daily use x average lead time). It is easy to do from a notebook and tends to be cautious.
  • Keep every figure in the same unit (pieces, litres, boxes). Results are rounded up to whole units.

Sources

  1. Standard inventory-control formulas; no regulatory source applies.

Rules and rates change. Always confirm against the current official text.

Free lessons that explain it

From the free Zeyto Academy. No account needed.

Get average daily use from real sales

Zeyto shows stock by item and warehouse with each item's history, and flags negative stock, so demand and lead time come from your own documents.

Try Zeyto freeSee the live demoSee Reorder Point and Safety Stock Planner: What to Order Today and How Much (Offline App for Shops and Kitchens), AED 69

Related templates and tools on the marketplace

Cite this tool

Page
Reorder point and safety stock calculator
Publisher
Zeyto (Emeron Infospace FZE)
Address
https://zeyto.app/tools/reorder-point-calculator
Zeyto. "Reorder point and safety stock calculator", free tool, Emeron Infospace FZE. https://zeyto.app/tools/reorder-point-calculator

You are welcome to link to this page. Please do not pass the results on as advice: each page says what it covers and what it leaves out.

Questions

Common questions

What is a reorder point?
The stock level at which you place a new order so that it arrives before you run out. It covers the demand expected during the supplier's lead time, plus a buffer called safety stock.
What is safety stock?
Extra stock held to cover demand that is higher than average or a delivery that is later than expected. The higher the service level you want, the more safety stock you hold, and the more cash it ties up.
Which method should I choose?
If you can estimate how much your daily demand varies, use the statistical method with a service level. If you only know your busiest day and your slowest supplier, use the simple method. Compare both and decide.
How do I find the standard deviation of daily demand?
Take the quantity sold on each of the last 30 or more days, and use the STDEV function in a spreadsheet. A larger number means more erratic demand.
Does this tell me how much to order?
No, only when. How much to order depends on supplier minimums, price breaks, storage and cash. The month-end and cash flow tools help you plan that side.

More free tools

Keep going

These tools are free templates and calculators. They are not tax, legal or accounting advice. See all free tools.