Reorder Point Calculator
Calculate Reorder Point metrics for ecommerce, SaaS, marketing, and operations.
This reorder point calculator finds the inventory level at which a new purchase order should be placed, based on average daily usage, supplier lead time, and a safety stock buffer - timed so new stock arrives before existing inventory runs out.
Enter your average daily usage, lead time, and safety stock, and the calculator returns your reorder point.
Worked Calculation Examples
| Scenario | Result | Calculation Step |
|---|---|---|
| 20 units/day average usage, 10-day lead time, 50 units safety stock | Reorder point = 250 units | Reorder point = (20 × 10) + 50 = 200 + 50 = 250 units. |
| 50 units/day average usage, 7-day lead time, 100 units safety stock | Reorder point = 450 units | Reorder point = (50 × 7) + 100 = 350 + 100 = 450 units. |
The Reorder Point Formula
Reorder point = (average daily usage x lead time in days) + safety stock. This ensures enough inventory remains to cover expected demand during the time it takes a new order to arrive, plus a buffer for unexpected demand spikes or supplier delays.
Why Lead Time Accuracy Matters
Reorder point calculations are highly sensitive to lead time estimates - underestimating how long a supplier actually takes to deliver can lead to stockouts even with a calculated reorder point in place, which is why using realistic, ideally historical, lead time data produces more reliable reorder triggers.
How to Use the Reorder Point Calculator
- Open the Reorder Point Calculator and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the reorder point calculator works.
Frequently Asked Questions
How do you calculate a reorder point?
Multiply average daily usage by supplier lead time in days, then add your safety stock buffer: reorder point = (daily usage x lead time) + safety stock.
What happens if lead time is underestimated?
Underestimating lead time can cause a stockout even if inventory reaches the calculated reorder point on schedule, since new stock won't arrive as quickly as assumed - using accurate historical lead time data helps avoid this.
Why include safety stock in the reorder point?
Safety stock provides a buffer against demand spikes or supplier delays beyond the expected average, reducing the risk of running out of inventory before a new order arrives.
How do I use this reorder point calculator?
Enter the known values, review the units or settings, and the calculator updates the result instantly. The formula and example on this page show how the answer is produced.
What does the Reorder Point Calculator calculate?
Calculate Reorder Point metrics for ecommerce, SaaS, marketing, and operations. It is designed for fast browser-based calculations without sign-up, downloads, or manual spreadsheet setup.
What formula does this reorder point use?
The formula is: Reorder Point = (Average Daily Usage × Lead Time) + Safety Stock. Reorder point formulas are a core component of inventory control theory developed throughout the 20th century, notably formalized within the Economic Order Quantity framework Ford W. Harris introduced in 1913 - one of the earliest mathematical models for balancing ordering costs against holding costs, still foundational to modern inventory management software and enterprise resource planning systems.
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Last updated: September 27, 2026.