The formula
Reorder point = daily sales × (supplier lead time + testing time) + safety stock.
Testing time matters in this category. A batch that has arrived but has not passed its lab test cannot be sold, so the clock does not stop when the box lands.
A worked example
| Input | Value |
|---|---|
| Average sales | 4 vials a day |
| Supplier lead time | 14 days |
| Lab testing turnaround | 5 days |
| Safety stock (one week of sales) | 28 vials |
| Reorder point | 4 × (14 + 5) + 28 = 104 vials |
When stock for that product drops to 104 vials, place the next order. If sales are seasonal or growing, recalculate each month.
Avoiding dead stock
- Order slow sellers in smaller quantities, even at a higher unit price.
- Sell older batches first, so no lab report goes stale on the shelf.
- Watch retest dates on batches that are moving slowly.
- Drop products that have not sold in 90 days, or offer them to wholesale buyers.
Use the free COA expiry calculator to plan retest timing.
How Purity helps
Purity tracks stock by batch and sells the oldest released batch first. A batch waiting on its lab report is held until the report is in, so the stock you see is the stock you can actually sell, and low stock shows before it runs out.
Common questions
- How much safety stock should a research store keep?
- Often one to two weeks of sales for top sellers, more if your supplier's lead time varies a lot.