inventory management

Bill of Materials: The Ultimate Guide for Small Manufacturers

We cover what is a Bill of Materials (BOM) is, how to create one and why it is an essential part of any manufacturing business inventory strategy.

A Bill of Materials (BOM) is more than just a list of components required to manufacture a product. It is the backbone of any production process, ensuring every step is meticulously planned and executed. Understanding how to create and manage a BOM effectively can significantly enhance your production efficiency, reduce waste, and ensure product consistency.

This comprehensive guide will delve into the intricacies of a Bill of Materials, providing you with the knowledge necessary to optimize your manufacturing workflow. Whether you are new to the concept or looking to refine your existing process, this guide has something for everyone. Welcome to the Ultimate Guide to a Bill of Materials.

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What is a Bill of Materials?

Let’s begin with the basics: a Bill of Materials (also known as BOM or BoM), is a comprehensive list of components, materials, and sub-assemblies needed to manufacture a finished product.

It essentially outlines the quantity, cost, and source for each item required to produce the final product which is useful for a number of reasons that we’ll discuss in detail later in this article.

Let’s quickly explore a very basic BOM example to better understand how it works in the real world.

Consider how you might make a wooden chair - listing out the materials and the quantities required would result in a list somewhat like this:

4 x wooden legs 2 x armrests 1 x seat 1 x backrest 12 x screws 8 x bolts 10ml Wood finish

This is the starting point for your bill of materials, from here, you would enhance to include information like the unit cost and the unit of measurements (i.e. “ml” for the wood finish, and “item” for the materials like the seat and backrest)

Benefits of Using a Bill of Materials

The importance of a Bill of Materials in inventory management and manufacturing processes cannot be overstated: creating and maintaining accurate BOMs is truly the cornerstone for effective resource planning in inventory management.

A BOM provides a clear, step-by-step guide for assembling the final product in the manufacturing process. It ensures that every component is accounted for, reducing the risk of production errors and enhancing overall efficiency. Moreover, a BOM is adaptable and can be modified as per the changes in product design or supply chain dynamics, making it an indispensable tool for businesses to stay competent and scalable in the ever-evolving market.

Alongside these points, here are some further key advantages on using BOMs:

  • Enhanced production efficiency: A well-planned BOM streamlines the production process, reducing the chances of errors and delays.
  • Reduced costs: By knowing exactly what components are needed, businesses can optimize their inventory levels to avoid overstocking or stockouts, saving on storage costs and avoiding lost sales. Consistent product quality: With a detailed BOM in place, every product will follow the same assembly process, ensuring consistency in product quality.
  • Scalability: As your business grows, so will the complexity of your products. Having a robust BOM system in place allows you to scale your production without compromising on quality or efficiency.
  • *Accurate cost estimation: A detailed BOM helps businesses accurately estimate the cost of production by including all necessary materials and their associated costs.
  • Streamlined procurement: With a BOM in place, purchasing departments can easily identify which materials are needed for production and order them accordingly.
  • Improved inventory control: If you know exactly which materials and their amounts required goes into each of your products you’ll have a much better handle on your inventory situation: forcasting amounts required to fulfil orders becomes a much easier and reliable process.

Types of Bill of Materials

Multiple types of BOM can be used, depending on the level of detail required and the specific needs of a business. It can be confusing to know what the difference is between the various BOMs that are in use out there, so we have created a quick rundown:

  • Engineering BOM: This is the most detailed type of BOM, providing all necessary information for production planning. It includes information such as part numbers, quantities, and also assembly instructions.

  • Manufacturing BOM: This type of BOM focuses more on the materials needed for production and may include additional details like vendor names and lead times.

  • Sales BOM: A simplified version of a BOM that is used for sales purposes to highlight key components and features to potential customers.

  • Modular BOM:  This type of BOM is used for products with interchangeable components, allowing for modular assembly.

  • Kitting BOM: A kitting BOM is used to group together materials needed to manufacture a particular product and can be used to streamline the production process.

The Key Components of a Bill of Materials

Although there is a bit of variability on exactly what is contained in a BOM, most typical BOMs will have the following bill of materials format:

  • Part numbers / SKU numbers: These are unique identifiers for each raw material in the BOM and are crucial for accurate inventory management as they allow you to ensure and locate that the exact part.
  • Description: A brief description of the component to ensure it is easily recognizable.
  • Quantity:: The number of units required for production.
  • Unit of Measurement:: The unit in which the component is measured (e.g., pieces, meters, kilograms).
  • Vendor information:::* Information about the preferred supplier or vendor, such as name and contact details.
  • Unit cost:: The cost of an individual unit, including any associated expenses such as shipping or handling fees.

When creating BOMs for multi-staged production processes, it is also important to include details such as sub-assemblies, work-in-progress (WIP) items, and finished products. This level of detail ensures a smooth and efficient production flow.

Read more: Bill of Materials: Real World Examples

Tips for Maintaining an Effective Bill of Materials

  • Keep it updated: Regularly review and update your BOMs to reflect any changes in product design or materials used.

  • Use a standardized format: Develop a consistent format for your BOMs to make it easier for employees across different departments to understand and use. Software can be hugely helpful in this task as it will ensure that you have a standardized approach.

  • Integrate with inventory management software: Using an inventory management software like Craftybase can significantly streamline the BOM creation process and improve overall production efficiency.

How to Create a Bill of Materials

Creating a BOM can be a time-consuming and detail-oriented task, which is why for many small manufacturers it is often neglected and dismissed.

Fortunately, there are many tools available to help streamline the process and remove those objections. You can use these approaches to learn how to make a bill of materials:

  • Spreadsheets: Many small businesses use spreadsheets like Excel or Google Sheets to create their BOM templates. These can be easily customized and updated as needed however they are difficult to maintain, particularly as your business grows and you have larger datasets to manage.

  • Inventory management or MRP software: As mentioned earlier, inventory management software with bill of materials such as Craftybase can significantly simplify creating and maintaining BOMs by integrating all necessary data in one place.

  • Enterprise resource planning (ERP) systems: For larger businesses that require more complex BOMs, an ERP system may be the best option. These systems integrate various aspects of business operations such as inventory management, accounting, and supply chain management.

Read more: How to create a Bill of Materials (BoM) in 7 easy steps


A Bill of Materials is a crucial tool for DTC brands looking to optimize their inventory management and streamline their manufacturing processes. By understanding its importance, benefits, types, key components, and best practices, businesses can utilize BOMs to their advantage and stay competitive in the market.

Nicole Pascoe Nicole Pascoe - Profile

Written by Nicole Pascoe

Nicole is the co-founder of Craftybase, inventory and manufacturing software designed for small manufacturers. She has been working with, and writing articles for, small manufacturing businesses for the last 12 years. Her passion is to help makers to become more successful with their online endeavors by empowering them with the knowledge they need to take their business to the next level.