EOQ and Lot Size Calculator for Infor VISUAL Parts
Lot size parameters sit in every VISUAL part record, and they are often left at whatever was set years ago. This tool shows the balance between setup cost and carrying cost and tells you what a different lot size is worth.
Your numbers
Setup labor plus machine downtime, or purchasing cost per PO.
Capital, storage, insurance, obsolescence.
Your results
Classic EOQ assumes constant demand and instant replenishment. Treat the result as a starting point, then adjust for pack sizes, minimum buys and capacity.
Annual setup plus carrying cost vs lot size
Sweeps Current lot size in use from 100 to 3000, holding your other inputs fixed.
Lot size review across your part master
Optional: send us a read-only extract and we return parts where the lot size looks far from economic.
Optional. The tool and every export work without this. No spam.
How to use it
Enter annual demand, the cost of one setup or purchase order, unit cost and a carrying cost rate. Then enter the lot size currently used on the part. The tool returns the economic quantity, orders per year and the annual cost of both options. The chart sweeps the lot size so you can see the curve is flat near the minimum, which means a lot of practical rounding is cheap.
- Include only costs that vary with the lot
- Use a realistic carrying rate, not just interest
- Check the result against the machine's minimum run
- Compare for A parts first, where savings matter
The formula behind it
Total annual cost is demand divided by lot size times setup cost, plus half the lot size times annual carrying cost per unit. Setting the slope to zero gives the economic order quantity, the square root of two times demand times setup cost divided by carrying cost per unit. At that point setup cost and carrying cost are equal. Purchase price is left out because it does not change with lot size unless there are price breaks.
Reading the result
If the saving is small, leave the lot alone. The cost curve is shallow, so a lot 20% off the optimum usually costs only a few percent more. A large saving suggests a setup cost that fell or a carrying rate that rose since the lot was last reviewed. A very high EOQ against demand can mean setup cost is overstated. Reducing setup time with SMED effort moves the optimum down far more than refining the formula does.
Common mistakes
Teams often include fixed overhead in setup cost, which inflates lots. Others use a 10% carrying rate that ignores space, handling and obsolescence. Another trap is applying EOQ to parts with lumpy or project demand, where lot-for-lot planning is better. Remember that pack size, tooling life and shelf life can override the calculated quantity. Finally, update the setup cost when processes change, because stale values quietly distort planned orders.
Frequently Asked Questions
Does EOQ apply to manufactured parts?
Yes, the same logic gives an economic run quantity when setup cost replaces ordering cost. Use the cost of one changeover. If the machine is a bottleneck, include the value of lost capacity in that cost.
What carrying cost rate is realistic?
Many manufacturers land between 15% and 30% a year once capital cost, storage, handling, insurance and obsolescence are counted. Use your finance team's figure when you have it.
How do quantity discounts change this?
Compute total cost including purchase price at each price break quantity and compare. EOQ alone ignores the price effect and can point at the wrong lot when discounts are steep.
Should I use it for every part?
Start with high-value or high-volume parts. For cheap low-volume parts the savings rarely justify the analysis, and a simple min and max rule is enough.
If you want lot sizes and setup costs checked across the whole part master from your ERP, we can build a read-only analysis for you.
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