May 10, 2023

Inventory Management Guide for Manufacturing Businesses

Ernane Iung

Ernane Iung – President and Owner of ei Funding

Inventory management is the lifeblood of any manufacturing business, serving as the backbone for efficient production processes, cost reduction and customer satisfaction. By maintaining an optimized inventory system, manufacturers can balance supply and demand effectively while minimizing operational costs and maximizing profitability.

But how exactly does inventory management work? And how do I know what tools and techniques are right for my business?

Whether you are a seasoned manufacturing professional or a newcomer to the industry, this guide will equip you with valuable knowledge and practical strategies to optimize your inventory management, paving the way for your business’s ongoing success.

How Do You Manage Inventory in Manufacturing?

Photo of manufacturing company employees walking through a warehouse

Identifying Your Inventory Types

Understanding the various types of inventory is the first step in managing them effectively. Manufacturing businesses typically deal with three primary inventory types:

  • Raw Materials: These are the essential components required to manufacture finished products. Proper management of raw materials inventory helps prevent stockouts, reduces waste and ensures smooth production processes.
  • Work-in-Progress (WIP): WIP inventory refers to partially completed goods in various stages of the production process. Tracking and managing WIP inventory is crucial for minimizing lead times, optimizing resource utilization and enhancing overall efficiency.
  • Finished Goods: Finished goods are completed products awaiting sale or distribution. Managing finished goods inventory ensures that products are readily available for customers, reducing the likelihood of lost sales and maximizing customer satisfaction.

Establishing Key Performance Indicators (KPIs)

In order to assess the effectiveness of your inventory management approach, it’s essential to monitor relevant KPIs. These metrics provide valuable insights into your inventory performance, helping you identify areas for improvement. Common KPIs in inventory management include:

  • Inventory Turnover: This metric measures the rate at which inventory is sold or used during a specific period. A high inventory turnover indicates efficient inventory management, while a low turnover may signal overstocking or slow-moving products.
  • Gross Margin Return on Inventory Investment (GMROII): GMROII calculates the gross profit generated for each dollar invested in inventory. It measures inventory profitability and helps businesses assess the financial return on their inventory investments. A higher GMROII value indicates better inventory performance and profitability.
  • Stockout Rate: The stockout rate measures the frequency of stock shortages or unfulfilled orders. A high stockout rate can result in lost sales and decreased customer satisfaction, making it crucial to address any underlying inventory management issues.

Continuously monitoring your inventory management performance, evaluating KPIs and staying informed about industry trends can help you identify areas for improvement and refine your strategy over time.

What Are the 4 Types of Inventory Management?

Photo of two manufacturing workers in front of some warehouse shelves

Now that we’ve covered the basics of inventory management in manufacturing, it’s essential to find the right approach for your business. The choice you make can greatly impact your efficiency and profitability. Let’s dive into some popular inventory management methods to help you determine the best option for your unique needs and goals.

Just-In-Time (JIT) Inventory Management

Just-In-Time Inventory Management is a strategy that aims to minimize inventory levels by ordering and receiving goods only as they are needed in the production process. This method originated in Japan, where Toyota initially developed it to increase efficiency and reduce waste in its manufacturing operations.


  • Reduces inventory holding costs
  • Minimizes the risk of obsolescence
  • Increases cash flow
  • Encourages continuous improvement in production processes


  • Requires accurate demand forecasting
  • Susceptible to supply chain disruptions
  • May lead to increased ordering and transportation costs

Best suited for:

  • Businesses with stable and predictable demand
  • Industries with short product life cycles

Economic Order Quantity (EOQ) Model

The Economic Order Quantity Model is a quantitative technique used to determine the optimal order size for inventory replenishment. Developed by Ford W. Harris in 1913, EOQ aims to balance the costs of ordering and holding inventory, minimizing the total cost of inventory management.


  • Minimizes overall inventory costs
  • Simplifies the ordering process
  • Reduces stockouts and overstock situations


  • Assumes constant demand and lead times
  • May not be suitable for products with seasonal demand or fluctuating lead times
  • Requires accurate cost estimations

Best suited for:

  • Businesses with predictable and steady demand
  • Products with relatively stable costs and lead times

Materials Requirement Planning (MRP)

Materials Requirement Planning is a computer-based inventory management system that helps manufacturers determine the quantity and timing of raw materials and components needed for production. MRP uses information such as production schedules, lead times and inventory levels to calculate material requirements and generate purchase orders.


  • Enhances production planning and scheduling
  • Reduces stockouts and excess inventory
  • Improves resource utilization and efficiency


  • Requires accurate and up-to-date data input
  • Can be complex and time-consuming to implement
  • May involve high initial investment in software and training

Best suited for:

  • Manufacturing businesses with complex production processes
  • Businesses with multiple products and production stages

Days Sales of Inventory (DSI)

Days Sales of Inventory is a financial metric that measures the average number of days it takes for a company to convert its inventory into sales. It helps businesses evaluate the efficiency of their inventory management and assess the effectiveness of their sales efforts.


  • Provides insights into inventory turnover and sales performance
  • Helps identify potential issues in inventory management
  • Aids in cash flow management and forecasting


  • May not provide a complete picture of inventory management efficiency
  • Could be influenced by factors such as seasonality and market conditions
  • May not be applicable to all types of inventory

Best suited for:

  • Businesses that want to monitor their inventory performance
  • Companies looking to optimize their sales and inventory management processes

What Is the Best Inventory Method for Manufacturing?

Photo of a warehouse employee from above next to massive crates of fresh apples

So you’ve looked into some popular inventory management strategies, but how do you figure out which is the right fit for your business? To choose the right approach, consider the following factors:

Industry Type

Distinct industries have unique requirements for inventory management, and the choice of method can significantly impact operational efficiency. For instance, manufacturers of perishable goods, such as fresh produce or dairy products, may benefit from Just-in-Time (JIT) inventory management, which minimizes inventory holding times and reduces the risk of spoilage.

On the other hand, businesses with intricate production processes, such as those in the aerospace or automotive industries, might find Materials Requirement Planning (MRP) more fitting, as it allows for precise coordination of raw materials, components and production schedules, ensuring the timely availability of resources and streamlined manufacturing workflows.

Business Size

The scale of your business is a key factor in selecting the right inventory management method. For smaller businesses with limited storage and a focused product range, Economic Order Quantity (EOQ) offers cost-effective replenishment by optimizing order quantities. Just-in-Time (JIT) is also well-suited for small businesses, as it minimizes inventory levels, reduces holding costs and enhances cash flow by aligning production with demand.

In contrast, larger organizations with complex production processes and diverse product offerings can benefit from Materials Requirement Planning (MRP). MRP integrates demand forecasts, production schedules, and inventory data to streamline planning, reduce stockouts and improve coordination — providing comprehensive inventory control and operational efficiency.

Market Volatility

Flexibility is key if your business faces a volatile market with fluctuating demand. Just-in-Time (JIT) inventory management provides the agility to adapt to market shifts by ordering inventory only as needed, minimizing excess stock and holding costs — ideal for industries like fashion and consumer electronics.

On the other hand, for businesses with stable demand, Economic Order Quantity (EOQ) calculates the optimal order quantity to balance costs, making it suitable for products with consistent demand. Materials Requirement Planning (MRP) integrates forecasting and planning, ensuring timely material availability for complex production processes—advantageous for industries like industrial equipment and bulk chemicals.

Demand Forecasting

The precision of your demand forecasts directly impacts the efficacy of your chosen inventory management method. For businesses with stable and predictable demand, Just-in-Time (JIT) offers lean inventory practices that reduce holding costs, while Materials Requirement Planning (MRP) enhances production planning and resource coordination.

However, for businesses facing demand fluctuations or seasonality, the Economic Order Quantity (EOQ) model calculates the optimal order quantity, balancing ordering and holding costs for data-driven replenishment.

Since no single inventory management method is universally suitable for all businesses, customizing your approach to align with your specific needs is essential. The solution may involve combining different techniques or adjusting your chosen method to better accommodate your business requirements. Ultimately, the goal is to find a method that enables your business to streamline inventory levels, reduce costs and maintain high customer satisfaction.

Technology in Inventory Management

Photo of someone using a tablet device in a warehouse with a digital inventory management tool

Harnessing the power of technology in inventory management is a game-changer for manufacturing businesses. The market offers a plethora of inventory management software solutions, ranging from standalone applications to modules integrated within comprehensive enterprise resource planning (ERP) systems.

By embracing technology in inventory management, manufacturing businesses can gain better visibility and control over their inventory processes, ultimately leading to reduced costs, enhanced operational efficiency, and improved decision-making. As technology evolves, staying current with the latest tools and best practices is essential for maintaining a competitive edge in the market.

Essential Features to Look For in Inventory Management Software:

  • Intuitive user interface and ease of use
  • Scalability and customization potential
  • Seamless integration with other business systems (e.g., accounting, sales, production)
  • Robust reporting and analytics capabilities
  • Real-time inventory tracking and updates
  • Demand forecasting and replenishment functionality
  • Mobile access and remote monitoring

What’s the Best Inventory Management Strategy?

Effective inventory management is vital for the success of any manufacturing business. But remember: There is no universal inventory management solution. The best inventory management strategy is the one that works for your business’s needs. By customizing and refining your inventory management strategy over time, you can ensure your manufacturing business remains agile, competitive, and well-equipped to meet the market’s ever-changing demands.

In addition to optimizing inventory management, maintaining healthy cash flow is crucial for the growth and stability of your business. That’s where ei Funding’s invoice factoring services come in. Invoice factoring can provide your manufacturing business with immediate access to cash tied up in unpaid invoices, helping you to cover expenses, invest in inventory or take advantage of growth opportunities.

With ei Funding’s flexible and tailored factoring solutions, you can focus on optimizing your inventory management strategy while ensuring a steady cash flow to support your business’s ongoing success.

Learn more about ei Funding can help your manufacturing business thrive:

Grow with Invoice Factoring


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