EOQ Calculator (Economic Order Quantity)
Use this eocalc calculator to estimate the best order quantity that minimizes your annual ordering and holding costs.
What is an EOQ calculator?
The eocalc calculator is a practical inventory planning tool built around the Economic Order Quantity (EOQ) model. EOQ helps you answer one core question: how much should I order each time to minimize total inventory cost? Instead of guessing, you use demand and cost data to find a mathematically balanced order size.
For businesses that hold stock—retail stores, ecommerce brands, manufacturers, and distributors—ordering too often increases purchasing admin and shipping costs, while ordering too much ties up cash and raises storage risk. EOQ finds the middle ground.
The EOQ formula
D = Annual demand (units/year)
S = Cost per order ($/order)
H = Annual holding cost per unit ($/unit/year)
This formula assumes demand and costs are relatively stable. In real life, no model is perfect, but EOQ gives a reliable baseline that can be adjusted with business context.
How to use this eocalc calculator
Step 1: Enter your key inputs
- Annual Demand (D): The number of units you expect to sell or use in a year.
- Cost per Order (S): The fixed cost of placing one purchase order (admin, freight setup, handling).
- Holding Cost (H): The yearly cost of carrying one unit in stock (storage, financing, insurance, obsolescence).
- Optional Inputs: unit purchase cost, lead time, safety stock, and working days for reorder planning.
Step 2: Click “Calculate EOQ”
The calculator returns the optimal order quantity and additional decision metrics, including reorder point and annual inventory cost breakdown.
Step 3: Use the results in purchasing decisions
EOQ is not just a number; it is a purchasing policy. Use it to set preferred lot size, order frequency, and reorder triggers in your inventory system.
Understanding the outputs
- EOQ (units/order): Recommended quantity each time you place an order.
- Orders per year: How often you will purchase if you follow EOQ.
- Time between orders: The expected interval between purchase orders.
- Average inventory: Typical on-hand stock level, including safety stock.
- Annual ordering cost: Total fixed order costs over a year.
- Annual holding cost: Total carrying cost over a year.
- Total relevant cost: Ordering + holding; the EOQ model’s main optimization target.
- Reorder point: The inventory level at which you should place the next order.
Worked example
Assume a product has annual demand of 10,000 units, order cost of $50, and holding cost of $2 per unit/year. EOQ computes to roughly 707 units per order. That implies about 14 orders per year. If you run 250 working days, you place an order every 17–18 days on average.
If lead time is 7 days, daily demand is 10,000/250 = 40 units/day. Reorder point is 40 × 7 = 280 units (plus any safety stock you choose). This gives your team a clear operational trigger rather than a gut-feel reorder decision.
Why EOQ matters for cash flow
Inventory is one of the biggest uses of working capital. EOQ helps reduce dead cash in excess stock while still protecting service levels. When paired with reorder points and safety stock, it provides a structured method for balancing efficiency and availability.
- Lower carrying costs through disciplined lot sizing
- Fewer emergency purchases and stockout penalties
- Improved planning consistency across SKUs
- Cleaner purchasing forecasts for suppliers and finance teams
Common mistakes to avoid
- Using incomplete holding cost: Include financing, storage, shrinkage, and obsolescence—not just warehouse rent.
- Ignoring seasonality: EOQ assumes steady demand. For seasonal items, recalculate by period.
- Forgetting lead time variability: Add safety stock when supplier lead times fluctuate.
- Never updating assumptions: Revisit inputs quarterly or when costs shift materially.
When to recalculate EOQ
Recompute EOQ whenever your demand forecast, shipping economics, or carrying cost profile changes. Fast-moving catalogs and volatile freight markets can make old EOQ values stale quickly. Many teams refresh monthly for A-items and quarterly for B/C-items.
Final takeaway
The eocalc calculator gives you a fast, data-driven way to set smarter order quantities. Start with reliable demand and cost estimates, calculate your EOQ, then apply reorder points and safety stock for day-to-day execution. Over time, this discipline improves inventory turns, reduces avoidable cost, and strengthens cash flow.