Calculator Inputs
Use the form below to estimate a practical minimum order quantity for ecommerce purchasing.
Plotly Cost Curve
This chart compares annual inventory cost across different order quantities so you can see where the recommendation fits.
Example Data Table
Use this sample scenario to understand the calculator fields and expected outputs.
| Example Input | Value | Why It Matters |
|---|---|---|
| Monthly Demand | 2,400 units | Sets the demand baseline for replenishment sizing. |
| Monthly Demand Std. Dev. | 300 units | Measures volatility for safety stock planning. |
| Lead Time | 12 days | Longer lead times raise buffer needs. |
| Order Cost | $85 | Higher order cost usually increases economic order quantity. |
| Supplier Minimum | 250 units | Creates a hard commercial floor for purchasing. |
| Case Pack / Increment | 25 / 25 | Rounds the order to operationally valid quantities. |
| Sample Output | Value | Interpretation |
|---|---|---|
| Economic Order Quantity | 1,076.61 units | Lowest-cost order size before operational constraints. |
| Safety Stock | 312.12 units | Inventory buffer protecting the service target. |
| Reorder Point | 1,272.12 units | Trigger level for placing the next order. |
| Recommended MOQ | 1,525 units | Rounded and feasible quantity for the sample case. |
Formula Used
EOQ = √((2 × Annual Demand × Order Cost) ÷ Annual Holding Cost per Unit)
Safety Stock = z-score × Daily Demand Standard Deviation × √Lead Time
Reorder Point = (Daily Demand × Lead Time) + Safety Stock
Shortage To Target = max(0, Reorder Point + Coverage Need − Net Available Inventory)
Base MOQ = max(EOQ, Shortage To Target, Supplier Minimum)
Recommended MOQ = Rounded Base MOQ adjusted to case pack, order increment, and available storage capacity.
How to Use This Calculator
- Enter your expected monthly demand and its standard deviation.
- Add lead time, purchase order cost, unit cost, and freight cost.
- Choose a service level to define how much stock protection you want.
- Enter supplier limits such as minimum quantity, case pack, and increment.
- Add storage capacity, current stock, incoming stock, and desired coverage days.
- Press calculate to see MOQ, EOQ, reorder point, cost estimates, and the cost curve.
- Use the CSV and PDF buttons to save or share the result summary.
FAQs
1. What is minimum order quantity?
Minimum order quantity is the lowest practical or required quantity you should buy in one purchase, based on supplier rules, economics, service level, and storage limits.
2. How is MOQ different from EOQ?
EOQ is the mathematically cost-efficient order size. MOQ is the final operational buying quantity after supplier minimums, pack sizes, service buffers, and capacity limits are applied.
3. Why does service level change the result?
A higher service level increases safety stock. That raises the reorder point and can increase the quantity needed to protect availability during supplier lead time.
4. Why include case packs and increments?
Suppliers often ship in fixed pack sizes or ordering multiples. Rounding to these values makes the recommendation practical and easier to purchase without manual adjustment.
5. What happens if storage capacity is too low?
The calculator limits the recommendation to free capacity. If that feasible amount falls below supplier minimums, the result warns you that the purchase may not be workable.
6. Should I use landed cost or product cost?
Use landed cost whenever possible. It reflects the true carrying value of inventory by including product cost plus inbound freight and related per-unit acquisition costs.
7. Can I use this for seasonal products?
Yes, but refresh the demand inputs often. Seasonal items need shorter review cycles and updated forecasts so the MOQ reflects current sales patterns.
8. How often should I review MOQ settings?
Review them monthly or whenever demand, lead time, freight, storage, or supplier terms change. Fast-moving catalogs may need weekly review.