Economic Order Quantity (EOQ) Calculator
Calculate the optimal order quantity that minimizes total inventory costs. Find the balance between ordering costs and inventory holding costs to optimize your supply chain and reduce expenses.
Includes processing, shipping, and receiving costs per order
Includes storage, insurance, obsolescence, and opportunity cost
Frequently Asked Questions
How the Economic Order Quantity Calculator Works
The EOQ calculator helps you determine the optimal quantity to order from suppliers by minimizing the combined costs of ordering and holding inventory. It balances two competing cost drivers: frequent small orders (high ordering costs) versus infrequent large orders (high holding costs).
Worked Example
Suppose your business has annual demand of 10,000 units, ordering cost of $50 per order, and holding cost of $5 per unit per year:
- EOQ = √(2 × 10,000 × $50 ÷ $5) = √(200,000) ≈ 447 units
- Number of orders = 10,000 ÷ 447 ≈ 22 orders per year
- Average order interval ≈ 16 days
- Annual ordering cost ≈ 22 × $50 = $1,100
- Annual holding cost ≈ (447/2) × $5 = $1,118
- Total annual inventory cost ≈ $2,218
Ordering this quantity approximately every 2-3 weeks minimizes your total inventory costs. Note how ordering and holding costs are nearly equal at EOQ—this is the cost-minimizing point.
When to Use This Calculator
- Supply Chain Optimization: Reduce ordering and holding costs by finding the optimal order quantity.
- Procurement Planning: Determine how frequently to order from suppliers and in what quantities.
- Budget Planning: Calculate expected annual inventory costs for financial planning and cash flow management.
- Supplier Negotiations: Use EOQ analysis to evaluate volume discounts and negotiate better terms.
- New Product Lines: Establish initial ordering quantities when launching new SKUs.
Common Mistakes to Avoid
- Underestimating Ordering Costs: Remember to include all labor, systems, and logistics costs in your ordering cost per order, not just freight.
- Forgetting Opportunity Cost: Holding costs must include the cost of capital tied up in inventory. If your required return on capital is 10% and average product cost is $20, holding cost should include $2 per unit per year.
- Using Annual Averages for Seasonal Products: For products with significant seasonality, calculate separate EOQs for peak and off-peak periods.
- Ignoring Volume Discounts: Suppliers often offer lower prices for larger orders. Compare the EOQ cost to the cost of ordering at volume discount quantities.
- Not Accounting for Lead Time: Combine EOQ with reorder point calculations to ensure orders arrive when needed.
Responsible Order Quantity Management
While EOQ minimizes costs mathematically, it assumes stable, predictable demand. In reality, demand varies seasonally, and suppliers may offer volume discounts or require minimum orders. EOQ provides an optimal target, but balance it with practical constraints like storage space, cash flow needs, and product shelf life. Regularly review and adjust your ordering strategy as market conditions and demand patterns change.