When should I reorder? Reorder point calculator
Enter how many units you sell on an average day and how long your supplier takes to deliver. The calculator gives you the stock level at which to place the next order, adds a safety stock for bad weeks and tells you whether today's stock is already below that line.
Calculator
From placing the order until the goods are ready to sell.
Leave empty for no buffer.
Shows how many days it will last.
Result
- Reorder point
- Safety stock
- Days of stock left
- What to do
The calculation runs in your browser; the numbers you enter are not sent anywhere.
Reorder point = average daily sales × lead time in days + safety stock. If you sell 12 units a day, delivery takes 5 days and you keep 20 units as a buffer, reorder when stock falls to 12 × 5 + 20 = 80 units.
How the reorder point is calculated
While you wait for a delivery, you keep selling. The reorder point is the stock level that covers exactly those sales, plus a buffer in case demand is higher or the supplier is late. Order when stock reaches it, and the new goods arrive before the shelf is empty.
The calculator uses these formulas and rounds units up:
- Demand during lead time = average daily sales × lead time
- Reorder point = demand during lead time + safety stock
- Simple safety stock = highest daily sales × longest lead time − average daily sales × average lead time
Choosing a safety stock
If you already know how many spare units you want on the shelf, enter them directly. If not, the simple method looks at your worst realistic case: a busy day combined with a slow delivery. It is easy to explain and works well for small shops, although it can be generous for very stable products.
Three products, three very different results:
| Product | Lead-time demand | Safety stock | Reorder point |
|---|---|---|---|
| Steady seller: 10 a day, 4 days | 40 | 10 | 50 |
| Busy season: 12 a day, 5 days (worst 18 a day, 7 days) | 60 | 66 | 126 |
| Slow mover: 0.5 a day, 10 days | 5 | 3 | 8 |
When to order and how much to order
The reorder point tells you when to order, not how much. The order quantity depends on your supplier's minimums, shelf space, cash and how often you want to order. A common rule is to order enough to cover the time until the next regular order, plus the lead time.
Review the numbers every few months and before seasons. Average sales and delivery times change, and a reorder point set a year ago can leave you either out of stock or sitting on money you could use elsewhere.
Practical scenario
Example: a cleaning product in a corner shop
A shop sells 12 bottles of a cleaning product a day, the wholesaler delivers in 5 days and the owner wants 20 bottles as a buffer. The reorder point is 12 × 5 + 20 = 80 bottles. With 100 bottles on the shelf today, stock lasts about 8.3 days, and the order should go out in two days when stock reaches 80.
Step-by-Step Implementation
1. Find your average daily sales
Divide the units sold in the last 30 to 90 days by the number of days the shop was open. Use a busier period if you are preparing for a season.
2. Measure the real lead time
Count from the day you place the order to the day the goods are on the shelf, not the supplier's promised delivery date.
3. Enter it as the minimum stock alert in GiroPS
Put the reorder point into the product's minimum stock alert field in GiroPS. Products at or below that level are flagged, so you can see what to order at a glance, and stock counts keep the quantities reliable.
Common Pitfalls & How to Avoid Them
Frequently Asked Questions
What is a reorder point?
It is the stock level at which you place a new order so that the goods arrive before you run out. It equals the demand during the delivery time plus a safety stock.
How do I calculate safety stock without statistics?
Use the simple method: highest daily sales × longest lead time minus average daily sales × average lead time. With 18 × 7 − 12 × 5 you keep 66 extra units.
Should lead time include weekends?
Count the days on which you sell. If the shop is open every day, use calendar days; if it is closed on Sundays, leave those out of both sales and lead time.
Is the reorder point the same as minimum stock?
Often they are used as the same thing. In GiroPS you enter it as the product's minimum stock alert, and the product is flagged when stock reaches it.