# Reorder point calculator

Check whether the current stock position has fallen below a simple reorder threshold. The result is a prompt to review an order, with the assumptions visible beside it.

Formula: Reorder point = expected demand during lead time + safety stock.

Example: Expected units sold per week 15; Delivery lead time in weeks 2; Safety stock in units 10; Usable units on hand 30; Confirmed units on order 0.
Result: Reorder point (units) 40.00; Stock position (units) 30.00; Gap to reorder point (units) 10.00.

## How to calculate it

1. Estimate weekly demand and multiply it by the supplier's delivery lead time in weeks.
2. Add safety stock in units. That gives the reorder point for this product under the chosen assumptions.
3. Add usable stock on hand and confirmed stock on order. Compare that stock position with the reorder point; a positive gap signals a review.

## A ten-unit gap is a prompt to review the order

A product sells 15 units a week. With a two-week supplier lead time and 10 safety units, its reorder point is 15 × 2 + 10 = 40 units. There are 30 usable units on hand and none confirmed on order, so the stock position is 30 and the gap to the point is 10 units.

The buyer should review an order now. Ordering exactly 10 units may still be wrong: the next order cycle, case pack and minimum order quantity can all change the buy. A promotion next week would also change expected demand.

## Check before acting

- Count only confirmed inbound units, and check whether they arrive before the stock is needed.
- Revisit demand and lead time after a supplier disruption or planned promotion.

## Questions

### What is a reorder point?

It is the stock-position threshold at which a team should review replenishment, based here on expected demand during delivery lead time plus safety stock.

### Is the gap the quantity I should order?

No. The gap only measures how far the stock position sits below this threshold. Order cycles, pack sizes, minimums and target stock after delivery still matter.

### Why include stock on order?

Confirmed inbound stock is part of the stock position and can prevent a duplicate order. Its arrival date still needs checking before relying on it.

[Use the interactive calculator](https://twelfth.ai/tools/replenishment).
[Download the replenishment CSV template](https://twelfth.ai/resources/retail-csv/replenishment.csv).
[Download the eight-tab workbook](https://twelfth.ai/resources/retail-metrics-template.xlsx).
[Read the replenishment glossary definition](https://twelfth.ai/glossary/replenishment).
Related calculators: [Weeks of cover calculator](https://twelfth.ai/tools/weeks-of-cover), [Sell-through calculator](https://twelfth.ai/tools/sell-through).
Source: https://twelfth.ai/tools/replenishment