ERP & MRP Planning calculator

Economic Order Quantity Calculator

Economic Order Quantity gives planners a quick lot-size estimate when demand is spread across a known number of order cycles. It is useful for checking whether ERP lot sizes, kanban quantities, or planned-order quantities are in the right range.

What this calculator does

  • Estimate a practical manufacturing order quantity from annual demand, planned order cycles, and lot-size adjustment.
  • a materials planner needs a quick production or purchase lot-size check
  • It estimates a practical replenishment or production lot size from demand and planned order frequency.

Formula used

  • Planning order quantity = annual demand quantity ÷ planned order cycles per year × lot-size adjustment factor
  • Compare the result with ERP minimum, maximum, fixed, and multiple lot-size rules.

Inputs explained

  • Annual demand quantity: Use forecast plus firm demand for the item, customer group, or production family.
  • Planned order cycles per year: Use the number of replenishment or production orders expected in a year.
  • Lot-size adjustment factor: Use 1.0 for a straight average lot, or adjust for MOQ, pack quantity, yield, or batching policy.

How to use the result

  • Use it during ERP cleanup, MRP review, production scheduling, S&OP prep, purchasing decisions, shortage meetings, capacity planning, or daily shop-floor execution reviews.
  • This is a planning estimate. Confirm final commitments against current ERP/MRP records, released BOMs and routings, inventory accuracy, supplier commitments, open work orders, quality holds, and shop-floor constraints.

Common questions

  • What is the Economic Order Quantity calculator for? It estimates a practical replenishment or production lot size from demand and planned order frequency.
  • What information do I need before using it? You need annual demand, planned order cycles, and any lot-size adjustment factor.
  • How should I use the result? Use it to compare ERP lot-size parameters, reduce excess inventory, or avoid too many small orders.
  • When is the result only an estimate? It is only an estimate when demand, inventory, lead time, routing hours, setup time, yield, supplier dates, or work-center capacity comes from forecast assumptions or stale ERP data instead of current orders and recent execution history.

Last reviewed 2026-05-12.