Direct answer
EOQ estimates the replenishment quantity that balances modeled annual ordering and holding costs under a simplified steady-demand, immediate-replenishment framework.
What this calculation tells you
EOQ provides a useful cost benchmark and sensitivity tool. Its square-root structure also shows that moderate input error often changes the optimum less dramatically than expected.
The model does not select suppliers, predict demand or guarantee service. Discounts, minimums and variable lead times require extended analysis.
Where it is used
Purchasing
Compare order-frequency and inventory-holding costs for repeat items.
Warehousing
Test whether theoretical lots fit space, handling and case constraints.
Manufacturing
Contrast purchase lots with production-lot or setup policies.
Small business
Make implicit ordering and carrying assumptions visible before setting a policy.
When this guide helps
- Frequent small orders create administration cost.
- Large batches increase storage and obsolescence.
- A supplier offers a quantity discount.
- A case pack prevents ordering the exact result.
Define the cost inputs
Ordering cost should reflect incremental cost per order; annual holding cost should reflect relevant capital, storage, insurance, loss and obsolescence on a consistent basis.
Check the classic assumptions
Stable demand, known costs, no shortages and effectively immediate replenishment simplify reality. Use EOQ as a benchmark when these are reasonable enough for the decision.
Compare feasible neighboring quantities
Round to case, pallet, minimum and capacity constraints, then compare total modeled cost near the theoretical point rather than forcing an impossible exact lot.
Extend or reject the model when needed
Quantity discounts, production replenishment, perishability and severe uncertainty may justify a different model or direct scenario comparison.
- Keep annual units consistent.
- Separate order timing from size.
- Document excluded costs.
Worked case: base EOQ
Annual demand 10,000 units, order cost 50 and holding cost 2 per unit-year.
EOQ=sqrt(500,000)=707.11 units.
Continuous model suggests about 707 units before pack-size rounding.
It assumes stable demand, replenishment and cost structure.
Reproduce this worked caseOpen Economic Order Quantity Calculator
Worked case: ordering cost falls
Order cost falls from 50 to 20.
EOQ=sqrt(200,000)=447.21 units.
Lower order cost supports smaller, more frequent orders in the model.
Minimums, freight breaks and capacity can override the unconstrained result.
Reproduce this worked caseOpen Economic Order Quantity Calculator
economic order quantity: compare assumptions, not just answers
Round to feasible packs and compare total relevant cost around the mathematical minimum. EOQ is flat near its optimum and should not imply false precision.
| Scenario | Key input | Decision output |
|---|---|---|
| Order cost 50 | H=2 | 707 |
| Order cost 20 | H=2 | 447 |
economic order quantity: calculation checklist
- Demand period annualized
- Holding cost per unit-year
- Order cost incremental
- Constraints tested
- Pack rounding compared
Practical questions
Frequently asked questions
Does EOQ include safety stock?
The classic order quantity is separate; safety stock influences average inventory and policy but does not normally change the basic EOQ formula.
Should EOQ be rounded?
Use feasible package quantities and compare nearby total costs because the optimum is often relatively flat.
Can EOQ be used for perishable goods?
Only with care; spoilage, shelf life and demand uncertainty can make the classic assumptions unsuitable.
Further reading
Authoritative sources
Use these primary and professional resources to check definitions, conventions, or requirements that may extend beyond this guide.