The EPEI Calculator helps manufacturing and production planners determine how frequently each product in a product family can be produced in a repetitive, cyclic sequence. EPEI stands for Every Product Every Interval and is a crucial metric in lean manufacturing. It aims to minimize inventory while improving product flow and responsiveness in multi-product production lines.
By calculating EPEI, businesses can schedule production efficiently, reduce changeover times, and ensure a smoother flow of goods to meet customer demand.
Category: Manufacturing Efficiency / Production Planning
Formula of EPEI Calculator
Standard Formula:
EPEI = (Available Production Time × Changeover Time) / (Total Time Available for Production − Total Changeover Time)
Simplified Formula (widely used):
EPEI = (Number of Products × Changeover Time) / Available Time
Detailed Breakdown of Variables:
EPEI
Measured in hours or days, this represents the time required to produce every product at least once within the production cycle.
Number of Products
Total number of different product types (SKUs) produced within the time period.
Changeover Time
The average time it takes to switch production from one product to another. This is typically measured in minutes or hours.
Available Time
The total time available for production during the cycle, excluding downtime, breaks, and planned maintenance.
Reference Table – Commonly Used Terms
| Term | Description |
|---|---|
| EPEI | Time to produce every product at least once |
| Changeover Time | Time needed to prepare the machine for a different product |
| Available Time | Productive time in a shift/day/week, minus maintenance or unplanned stops |
| SKU | Stock Keeping Unit; unique product identifier |
| Cycle Time | Time it takes to produce one unit |
Example of EPEI Calculator
Let’s say a production line manufactures 5 unique products.
- Changeover Time: 30 minutes (0.5 hours)
- Available Time per shift: 8 hours
Using the formula:
EPEI = (5 × 0.5) / 8 = 2.5 / 8 = 0.3125 days
Interpretation:
The production system can manufacture every product every 0.31 days (or approximately once every 7.5 hours), assuming a steady production pace and minimal downtime.
Most Common FAQs
An ideal EPEI is short enough to ensure frequent product delivery but long enough to avoid excessive changeovers. The goal is to strike a balance between agility and efficiency.
Yes. You can reduce EPEI by shortening changeover times, increasing overall equipment effectiveness (OEE), or streamlining scheduling through lean tools like SMED (Single-Minute Exchange of Die).
EPEI is more common in repetitive or batch production environments but can be adapted for use in discrete systems where similar products are made in sequences.