EPQ Calculator

EPQ Calculator is a free, no-signup web tool that computes the Economic Production Quantity (optimal production lot size) for manufacturers, using the full EPQ formula that accounts for finite production rates rather than the instant-replenishment EOQ approximation.

What is EPQ Calculator?

EPQ Calculator is a browser-based utility created and maintained by Sathapana that solves the Economic Production Quantity model. You enter annual demand, setup cost per run, holding cost per unit per year, and daily production rate (plus working days per year); it returns the optimal lot size, maximum inventory, runs per year, run time, cycle length, total annual cost, and cost per unit. It also compares the result against plain EOQ, showing how much larger the EPQ is and how much holding cost it saves. All calculations run locally in your browser, so your numbers never leave your device.

Key Features

• Free, no signup — no account required; runs entirely in your browser with no server upload.
• Single SKU and multi-SKU batch CSV — compute one item at a time or upload a CSV with columns SKU, D, S, H, p and optional wd (working days); a sample file is available.
• Full EPQ model — uses the complete formula √(2DS / (H(1 − d/p))), including the production-rate term that EOQ ignores; requires p > d.
• EOQ comparison — reports the EOQ lot size, the percentage by which EPQ is larger, annual holding cost saved, and the extra total cost you'd pay if you used EOQ.
• Scheduling outputs — run time per batch and cycle length between runs, ready for production planning.
• Excel export — export results to Excel with one click.
• Linked Safety Stock and Reorder Point tools — continue to the next two planning steps from the calculator's results.
• Embeddable widget — free HTML snippet to embed the calculator on your own site.

Who is it for?

• Manufacturers and production planners — size production runs to minimize setup and holding cost, and get run time/cycle length for scheduling.
• Operations managers — compare EPQ against EOQ to justify larger batch sizes and quantify holding-cost savings.
• Students and educators — verify the EPQ formula, see the cost curve, and study the derivation and assumptions.
• Inventory analysts — use it as step one in a three-tool chain: EPQ → Safety Stock → Reorder Point.

What can you do with EPQ Calculator?

• Plan a single SKU: Enter demand, setup cost, holding cost, and production rate to get the optimal lot size and full cost breakdown in one click.
• Batch-process a product line: Drop a CSV with many SKUs, and the calculator computes the EPQ for every item at once, then export the results to Excel.
• Schedule production: Use the run time and cycle length outputs to plan when each item should run.
• Tune your inventory policy: Click through to the Safety Stock calculator and then the Reorder Point calculator to set buffers and reorder triggers.

How does EPQ Calculator work?

Enter your inputs in the Single SKU tab (or upload a CSV in the Multi-SKU tab) and press Calculate EPQ. The calculator derives daily demand from annual demand and working days, evaluates the production-rate term (1 − d/p), and returns the lot size, inventory peak, run frequency, run time, cycle length, and total annual cost. A worked example is available with one click to load.

Pricing

EPQ Calculator is free, with no signup required. There are no paid tiers or usage limits mentioned; the embedded widget is also free to use on your own site.

FAQ

What is the Economic Production Quantity (EPQ)?

EPQ is the optimal production lot size that minimizes combined setup and holding cost when a company produces inventory in-house at a finite rate, rather than receiving a full order at once.

How is EPQ different from EOQ?

EOQ assumes inventory arrives instantly in one delivery, so peak inventory equals the whole order. EPQ assumes you produce units gradually while also consuming them, so peak inventory stays below the full lot. This makes EPQ larger than EOQ and lowers average holding cost.

What is the EPQ formula?

EPQ = √((2 × D × S) / (H × (1 − d/p))), where D is annual demand, S is setup cost per run, H is annual holding cost per unit, d is the daily demand rate, and p is the daily production rate. The model requires p > d.

When should I use EPQ instead of EOQ?

Use EPQ when you manufacture the item yourself and production happens over time at a finite rate. Use EOQ when you purchase the item and receive the full order in a single delivery.

Why does the EPQ formula include (1 − d/p)?

Because you consume units while you are still producing them. Inventory grows at only (p − d) per day during a run instead of arriving all at once, so it peaks at Q × (1 − d/p) rather than Q. That lower average inventory reduces holding cost, which makes the optimal lot size larger than EOQ. If p is far greater than d, the term approaches 1 and EPQ becomes EOQ.