Quick answer
Reorder point = average daily demand × lead time + safety stock. Selling 40 units a day with a 7-day lead time and 60 units of safety stock gives a reorder point of 340, with 280 units used during the lead time.
Enter daily demand, lead time and safety stock. The calculator returns the stock level at which to reorder. Use this inventory reorder point calculator to check your own figures.
Related tools: Inventory Turnover Calculator: How many times inventory is sold and replaced. Economic Order Quantity Calculator: Order size that minimizes ordering and holding costs. Dew Point Calculator: Dew point from temperature and relative humidity.
How to use the Inventory Reorder Point Calculator
- Enter average daily demand (units) (above 0).
- Enter lead time (days) (above 0).
- Enter safety stock (units) (0 or more).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Average daily demand | A number, in units | > 0 |
| Lead time | A number, in days | > 0 |
| Safety stock | A number, in units | ≥ 0 |
Formula and method
Formula
reorder point = daily demand × lead time + safety stock
IEEE-754 double precision; shown to the decimals indicated.
Safety stock is your own buffer against variability.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Average daily demand = 40; Lead time = 7; Safety stock = 60.
| Result | Value |
|---|---|
| Reorder point | 340 |
| Demand during lead time | 280 |
Example 2
Inputs: Average daily demand = 12.5; Lead time = 14; Safety stock = 0.
| Result | Value |
|---|---|
| Reorder point | 175 |
| Demand during lead time | 175 |
The first line is the headline result (reorder point). Below it the inventory Reorder Point Calculator lists demand during lead time, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
What each part does
Demand during the lead time (280 units) is what you will sell while waiting for delivery. Safety stock (60) is a cushion for unexpectedly high demand or a late shipment. Reorder when stock falls to 340.
Setting safety stock
A common approach sets it from the variability of demand and lead time and a service level, such as z × standard deviation of demand during the lead time. Safety stock can be zero if supply and demand are very predictable.
How the result changes with average daily demand
Holding every other input at the first worked example, this table changes only average daily demand. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Average daily demand | Reorder point | Demand during lead time |
|---|---|---|
| 20 | 200 | 140 |
| 40 | 340 | 280 |
| 80 | 620 | 560 |
| 160 | 1,180 | 1,120 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Average daily demand: entering "0" shows "Average daily demand must be greater than 0." beside that field and no result.
- Safety stock: entering "-1" shows "Safety stock must be at least 0." beside that field and no result.
Choosing between the Inventory Reorder Point Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Inventory Turnover Calculator](/business/inventory-turnover-calculator/) | cost of goods sold, beginning inventory and ending inventory | Inventory turnover |
| [Economic Order Quantity Calculator](/business/economic-order-quantity-calculator/) | annual demand, cost per order and holding cost per unit per year | Economic order quantity |
| [Dew Point Calculator](/science/dew-point/) | air temperature and relative humidity | Dew point |
| [Basis Point Calculator](/finance/basis-point/) | value and convert | Percent |
| [D&D Point Buy Calculator](/other/point-buy/) | sTR score, dEX score and cON score | Points spent |
Background: business metrics
Business ratios depend on exactly which costs and revenues you include, so read each page's definition. Two common checks: break-even units = fixed costs ÷ (price − variable cost per unit), so $50,000 of fixed costs with a $10 price and $5 variable cost breaks even at 10,000 units; and net profit margin = net profit ÷ revenue, so $20,000 profit on $100,000 revenue is 20%.
Return on investment ignores time: 20% over five years is far less impressive than 20% in one, so compare returns over the same period.
Assumptions and limitations
- Safety stock can be zero
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for average daily demand and safety stock to confirm this.
Frequently asked questions
What is lead time?
The time between placing and receiving an order.
How do I choose safety stock?
Based on how costly a stock-out is versus holding extra.
Does it tell me how much to order?
No; use economic order quantity.
What does the Inventory Reorder Point Calculator calculate?
Stock level at which to reorder. It returns Reorder point and Demand during lead time.
What formula does the Inventory Reorder Point Calculator use?
reorder point = daily demand × lead time + safety stock. Safety stock is your own buffer against variability.
What do I need to enter in the inventory Reorder Point Calculator?
You enter Average daily demand (units), Lead time (days) and Safety stock (units).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Safety stock can be zero.
What is an example of a inventory Reorder Point result?
With average daily demand 40, lead time 7 and safety stock 60, the reorder point is 340.
Related calculators
- Inventory Turnover Calculator — How many times inventory is sold and replaced.
- Economic Order Quantity Calculator — Order size that minimizes ordering and holding costs.
- Dew Point Calculator — Dew point from temperature and relative humidity.
- Point Estimate Calculator — Point estimates of a proportion (MLE, Laplace and Wilson).
Sources
- Common definition used on this page. No single authoritative standard defines it, so the exact formula is stated in the formula section above
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.