EOQ with Discount Calculator

How to Use This Tool

Follow these steps to calculate your optimal order quantity with volume discounts:

1. Enter your annual demand for the product, selecting the appropriate unit (pieces, boxes, etc.).
2. Input your fixed ordering cost per purchase order, and select your local currency.
3. Choose your holding cost type: fixed amount per unit per year, or a percentage of the unit price.
4. Enter your holding cost value, which will adjust units automatically based on your selected type.
5. Fill in the 3 price break tiers with their minimum order quantities (MOQs) and corresponding unit prices.
6. Click Calculate to see your optimal order quantity and full cost breakdown.
7. Use the Reset button to clear all fields and start a new calculation.

Formula and Logic

The EOQ with Discount model compares total inventory costs across all available volume pricing tiers to find the lowest overall expense. For each price tier, it calculates:

• Base EOQ: √(2 * Annual Demand * Ordering Cost / Holding Cost per Unit)
• Feasible Quantity: If the base EOQ meets the tier’s MOQ, use the EOQ. If not, use the tier’s MOQ.
• Total Annual Cost per Tier: (Annual Demand / Feasible Quantity) * Ordering Cost + (Feasible Quantity / 2) * Holding Cost + Annual Demand * Tier Unit Price

The tool selects the tier with the lowest total annual cost as the optimal ordering strategy.

Practical Notes

These business-specific tips will help you apply results accurately to your supply chain:

• Price breaks must be sorted from highest price (lowest MOQ) to lowest price (highest MOQ) for accurate calculations.
• Holding costs typically range from 20-30% of unit cost for physical goods, covering warehousing, insurance, and obsolescence.
• Ordering costs should include all fixed expenses per order: staff time, shipping, inspection, and paperwork.
• If your supplier offers more than 3 price breaks, you can adjust the highest and lowest tiers to cover your full pricing structure.
• Always confirm MOQ requirements with your supplier, as they may change based on seasonal demand or contract terms.

Why This Tool Is Useful

Small businesses and e-commerce sellers often overorder to hit volume discounts, only to incur higher holding costs that erase savings. This tool helps you:

• Avoid overstocking by balancing discount savings against storage and ordering expenses.
• Compare multiple supplier pricing tiers in one view to negotiate better terms.
• Make data-driven purchasing decisions instead of relying on guesswork or supplier recommendations.
• Reduce total inventory spend by 10-30% for businesses with consistent annual demand.

It is especially valuable for traders managing bulk inventory and e-commerce sellers with multiple SKUs.

Frequently Asked Questions

What if my supplier offers more than 3 price breaks?

You can consolidate tiers by grouping similar MOQ ranges, or adjust the 3 input tiers to cover your lowest price (highest MOQ), middle price, and highest price (lowest MOQ) tiers. The tool will still return the optimal quantity across the tiers you enter.

How do I calculate holding cost as a percentage?

Add up all annual storage-related expenses (warehouse rent, insurance, labor, depreciation) and divide by your total average inventory value. Most businesses use 20-30% for physical goods, but this varies by industry.

What if the EOQ for a price tier is below the MOQ?

You must order at least the tier’s MOQ to qualify for that price. The tool automatically uses the MOQ as the feasible quantity for that tier, then compares total costs across all tiers to find the best option.

Additional Guidance

Revisit your EOQ calculations quarterly, as demand, ordering costs, and supplier pricing may change over time. For seasonal products, use peak season demand for calculations to avoid stockouts. Always factor in lead times when setting reorder points, as this tool calculates optimal order quantity but not timing. If you have multiple suppliers for the same product, run separate calculations for each to compare total costs.