Inventory guides
Reorder quantity calculator: how much stock to order
Enter the stock you have, your low-stock level, and how much you used or sold in the last 30 days. The calculator suggests how much to reorder and how long your current stock will last. It uses the same formula as the reorder suggestions in Countstead Pro.
Calculate a reorder quantityDownload Countstead
Calculate how much to reorder
Use figures for one item at one location, in the same unit. The example values are a candle maker’s; replace them with your own.
Free to use, with no sign-in. The calculation runs in this browser tab and doesn’t change your inventory.
The formula
Suggested reorder = low-stock level + use in the last 30 days − stock on hand
Days of stock left = stock on hand × 30 ÷ use in the last 30 days
A result below zero means there’s nothing to reorder yet. Days of stock are rounded down.
How the reorder quantity is worked out
Add your low-stock level to the last 30 days of use, then subtract what you have. Ordering that amount brings your stock up to the low-stock level plus 30 days of use, if you use nothing more before it arrives. If what you have already covers both, the result is zero.
Take the candle maker from the low-stock threshold calculator. Their low-stock level is 12 candles, and they sold 24 in the last 30 days. With 9 candles left, the suggested reorder is 12 + 24 − 9 = 27. At that rate, the 9 candles last about 11 days: 9 × 30 ÷ 24 = 11.25, rounded down.
| Stock on hand | Days left | Suggested reorder |
|---|---|---|
| 12 | 15 | 24 |
| 9 | 11 | 27 |
| 4 | 5 | 32 |
| 0 | None in stock | 36 |
Reorder point vs reorder quantity
The reorder point tells you when to order; Countstead calls it the low-stock level. The reorder quantity tells you how much to order once an item gets there. Set the level first: the low-stock threshold calculator works it out from your recent use, the time it takes to restock, and a buffer.
Some textbooks use the economic order quantity (EOQ) instead. It weighs the cost of placing an order against the cost of holding stock, so it needs cost figures. This calculator works from quantities you can read from your records.
Adjust the number before you order
The suggestion uses only the three figures you entered, so check the things it can’t see.
Round up to full packs
If candles come in boxes of 12, a suggestion of 27 means 3 boxes, or 36 candles. Enter a pack size in the calculator to see this.
Subtract stock already on its way
Stock on hand leaves out anything you’ve ordered that hasn’t arrived. If 12 candles are already on order, reorder 15 instead of 27.
Think about the weeks ahead
The last 30 days may not match the next 30. Before a busy season, or after a one-off market weekend, change the amount to what you expect to sell.
Check the count
A suggestion based on a wrong balance repeats the mistake. If the stock on hand looks wrong, count the item before you order.
Reorder suggestions in Countstead
In Countstead, give an item a low-stock level at each location where you keep it. When the balance at a location is at or below that level, the item appears in the free Low stock list on the Reports tab.
For each item on that list, Countstead Pro shows how much was used in the last 30 days, about how many days of stock are left, and a suggested reorder, using the formula on this page. It counts the stock you recorded leaving that location with Remove stock; transfers, counts, and deliveries aren’t included.
With Pro, tap Share reorder list to pass the suggestions on as text with a CSV file attached. The list gives each item’s location, stock on hand, days of stock, and suggested quantity. Sharing the list doesn’t place an order.
Common questions
- What if nothing sold in the last 30 days?
- You won’t get a suggestion, from this calculator or from Countstead. With no recent use, there’s no rate to plan from. Decide whether the item still needs a low-stock level, or order what you expect to sell.
- Should I count stock that’s already on order?
- Not as stock on hand. Enter only what’s at the location, then subtract the incoming amount from the suggestion. Countstead doesn’t track orders you’ve placed, so do the same with its suggestions.
- Why the last 30 days?
- It reflects how the item is selling now, and it’s the period Countstead Pro uses, so the same figures give the same result in the app.
- Can I use it for products I make?
- Yes. Treat the suggestion as the size of your next batch, and include the time it takes to make a batch when you set the low-stock level.
Try the inventory demo
Add an item and record stock movements in the browser. The demo is a working example; camera scanning is simulated.
Try the inventory demoAbout this guide
Written by Imdad Ismail, an independent developer in Sri Lanka who makes Countstead. Where a guide gives steps in Countstead, they match the version on the App Store. To report a mistake, email [email protected].