Reorder level calculator
Work out when to reorder each item using your own figures. Check the assumptions before you act on the result.
Your figures
Result
- Reorder level
- 810.00 units
How it is worked out
reorder level = average daily use x lead time in days + safety stock
reorder_level = average_daily_use*lead_time_days+safety_stock
What it works out
The reorder level calculator turns records from the business into a figure for this decision: when to reorder each item. Use it when the responsible stores manager and purchase manager needs a consistent answer for this specific task. The answer uses only the values entered. Record the measurement period beside it.
What you need
| Input | Unit | Where to find it |
|---|---|---|
| Average daily use (example: 90 units/day) | units/day | Use the stores issue register to calculate average daily use for the same item and working-day basis. |
| Lead time days (example: 7 days) | days | Use the supplier commitment record and actual GRN dates for lead time days. |
| Safety stock (example: 180) | units | Check the stock ledger, stock count, approved BOM or last receipt for safety stock. |
Use the same item, period and measurement unit for related inputs. If a figure comes from an estimate rather than an actual record, mark it as estimated. Keep your original figures beside the result.
The formula
In plain words, calculate reorder level using the measured inputs below. The expressions are shown without hidden rounding so they can be checked by hand.
- reorder level:
reorder_level = average_daily_use*lead_time_days+safety_stock.
Formula basis from the supplied taxonomy: reorder level = average daily use x lead time in days + safety stock. The calculation assumes the named inputs describe the same job and accounting period. Keep quantities, rates and measured units consistent.
A worked example
Illustrative example: a packaging manufacturer uses the figures in the table above. These are example inputs, not industry averages. For this example, the main figures are average daily use: 90 units/day, lead time days: 7 days, safety stock: 180.
- Reorder level:
average_daily_use*lead_time_days+safety_stock. With the example figures,90.0 * 7.0 + 180.0gives 810.
How to act: Use the result to compare it with the next purchase date. Write down the input date and the assumption that could move most.
How to read the result
Example bands, change them for your business:
- Comfortable: Your result meets the target for this item or reporting period. Keep the calculation with its source records and compare it with the next purchase date.
- Watch: The result is close to your action limit, or it changed since the previous calculation. Recheck average daily use and lead time days using the original records.
- Act: The result breaks a limit already agreed by the manager or owner. Record the difference, name a responsible person, and agree a correction date. For an operational starting point, read [Outdated reorder levels](/problems/outdated-reorder-levels) and [Purchase requirement to material received](/processes/purchase-requirement-to-material-received). Do not use these example bands as published industry benchmarks.
Copy it into a spreadsheet
Create a sheet with column A for the label and column B for the number or formula. The expressions work in Excel or Google Sheets. Keep input cells editable and result cells protected from typing.
| Cell | Label | Value or formula |
|---|---|---|
| B2 | average daily use | 90.000000 |
| B3 | lead time days | 7.000000 |
| B4 | safety stock | 180.000000 |
| B6 | reorder level | =((B2*B3)+B4) |
For any formula containing a divisor, enter a value above zero. For any monetary output, format the cell in Indian rupees. Do not replace the cells with rounded figures until the final display.
What this calculator leaves out
- Demand jumps, seasonality, minimum supplier order sizes and rejected receipts can change the decision.
- A single average can hide unusual lots, customers or weeks. Review the underlying entries before making a large decision.
- The formula does not check whether the records are complete. Check the stores register and the open PO list before buying. A number from last quarter may no longer represent the next delivery.
Common mistakes
- Mixing periods. Using average daily use from one month with lead time days from another produces a number that looks precise but is hard to act on.
- Trusting old figures. Recheck the relevant source record before reusing last month's saved inputs. If the calculated number conflicts with a physical stock count, reconcile the shelf and the book before placing an order.
- Treating an estimate as approval. Record which assumptions were entered by hand. Get the relevant owner, accountant or technician to check unusual values.
A number like this helps only if someone works it out again when things change.
Questions people ask
Where do I find the numbers for reorder level calculator?
Use the stores issue register to calculate average daily use for the same item and working-day basis. Use the supplier commitment record and actual GRN dates for lead time days. Keep all inputs from the same period.
Can I use this number to approve a purchase or payment?
Use it as a first check. Use the result to compare it with the next purchase date. Write down the input date and the assumption that could move most. If the result affects tax, legal duties, workplace safety or a major investment, obtain the appropriate review.
When should I calculate it again?
Recalculate when a meaningful input changes, and at the next regular review of the relevant register. Save the date and the input values so changes can be explained.