One of my products sells only two a week: how do I get a sensible reorder point for such a slow item?
Enter daily demand as a decimal: two a week is about 0.29 a day. The calculator multiplies it by the lead time, adds safety stock, then rounds the reorder point up to whole units, because you cannot hold part of an item. For slow sellers, choosing the safety stock in whole units matters more than the demand part itself.
The example in numbers
You sell two of a product a week, the supplier needs 21 days, and you want a buffer of 3 units. You entered daily demand as 0.29.
Demand during lead time: 0.29 × 21 = 6.09 units.
Reorder point: 6.09 + 3 = 9.09, and the calculator adds a line underneath, 'Rounded up to whole units': 10 units.
With a buffer of 2 units: the point is 8.09, rounded up to 9 units.
The calculator also adds a note: you cannot hold part of a unit, so reorder when stock reaches 10 units. Rounding up is deliberate. Round down to 9 and you would be ordering after already eating into the buffer you chose.
Watch the rounding of daily demand too
Two a week is exactly 2 ÷ 7, about 0.2857. Enter 0.2857 instead of 0.29 and demand during lead time becomes exactly 6, so with 3 units of safety stock the reorder point is 9 units, not 10. A difference of one unit came purely from rounding daily demand up a touch. On a fast seller that would not matter; on a slow one, a single unit is half a week of sales. Pick between them on purpose: 0.29 is one unit more cautious, 0.2857 is more precise.
Why safety stock matters more here
- Slow items do not sell evenly: two weeks can pass with no sale, then three go in one day. The 0.29 average hides that lumpiness.
- A single customer ordering two units can take half the buffer in one go.
- On the other hand, every extra unit sits for weeks before it sells, so a big buffer ties up cash and shelf space for longer than it would on a fast item.
- So think of safety stock as a concrete number of units you can live with holding, not as a share of sales.
The steps
- Work out daily demand over a long enough stretch, such as the last three months, because a single week says nothing about a slow item.
- Enter it in the Inventory reorder-point calculator to two or four decimals, with the lead time and the safety stock in units.
- Read the whole-units line and use it as your reorder level.
- Before ordering, check whether a bigger pack from the supplier is really cheaper per unit with the Unit-price comparison, bearing in mind that on a slow item a bigger quantity sits on the shelf longer. Then send the order with the Purchase-order generator.
Common questions
Does such a slow item need a reorder point at all?
If running out loses you customers or holds up orders that include other products, yes. If it can simply be ordered when needed without harm, a very low point, or ordering on each sale, may be enough.
Why can't I enter weekly sales directly?
Lead time is in days, so demand must be per day for the multiplication to line up. Divide weekly sales by 7 and enter the result.