Principal Engineer vs. Senior Engineer: Roles and Differences

Updated March 10, 2023

Principal engineers and senior engineers are both crucial roles in ensuring engineering teams can collaboratively research, design, analyze and inspect structures according to their client requirements. Staff engineers look to both of these professionals for guidance on specific projects and field expertise. Understanding the differences between these roles can help you decide if a career in either is right for you.

In this article, we discuss what principal engineers and senior engineers do and examine some ways they differ.

What is a principal engineer?

A principal engineer is an engineering professional with many years of experience in their field. They oversee projects and staff after working as engineers in a particular field. Different from other engineers, the role of principal engineer is a leadership role where they guide staff to ensure an engineering team completes projects on time and within budgets.

What does a principal engineer do?

Some key responsibilities of a principal engineer include:

Planning engineering strategies for a company
Managing engineering departments in tasks like research and design
Determining department goals and creating implementation plans
Providing expert advice to other engineers
Creating and managing engineering budgets
Negotiating contracts with vendors
Implementing process improvements

What is a senior engineer?

Senior engineers are engineering professionals who earn this title through experience. People in this role may handle several projects simultaneously, performing tasks of engineers and providing guidance for teams. These engineers are highly technical and ensure teams apply common engineering principles and concepts to their own teams' responsibilities.

What does a senior engineer do?

Some common duties of a senior engineer include:

Generating reports and writing project proposals
Presenting design and research to customers
Advising staff with process recommendations
Negotiating project and product terms with vendors
Overseeing projects

Differences between a principal engineer vs. a senior engineer

Principal and senior engineers can be similar in a few ways. For example, they both require at least a bachelor's degree in engineering in their particular specialty. They also both require problem-solving and technical skills and may perform leadership duties. Though they may seem similar, there are still several key differences between principal engineers and senior engineers:

Job title

The role of the principal engineer is an official position that companies offer for professionals with the needed experience, education and skill set. Senior engineer can be an official job title or simply an indicator of seniority that you earn after working with a company for years. Staff engineers can have titles like staff engineer I, staff engineer II, staff engineer III that indicate seniority based on experience.

Hierarchy

Principal engineers are higher-level positions compared to senior engineers. The common hierarchy for these jobs from lowest to highest is:

Depending on how large a firm is, principal engineers have their own hierarchy. Ranks from lowest to highest are:

Principal engineer
Senior principal engineer
Distinguished principal engineer
Fellow

Reporting

On some job sites or in some companies, senior engineers may report directly to leadership within their department. Principal engineers report to senior leadership at a company. Senior engineers may communicate their project details like budget and timeline to their leadership and principal engineers may review data across different job sites to track how the company is doing as a whole.

Required experience

Since both senior and principal engineers are leadership roles, both require years of experience. Many companies require between ten to fifteen years of experience. Some firms require prospective principal engineers serve as senior engineers for a few years prior to advancing.

Duties

Senior engineers are often more technical and focused on creating innovative solutions within their projects. Principal engineers research and recommend developments in the field. For example, by observing engineering teams and projects, they may determine new theories and policies that engineers across the field can use and learn from.

Similarly, if working in a lab senior engineers must determine solutions that are important for the lab's success. There may be few precedents set so it's important that they're innovative in their leadership and execution. The principal engineer's work in the lab ensures long-term success and credibility. All decisions they make can affect the lab or department.

Skills

Although both roles share common skills, how they use them can differ. Here are some skills they use and how they apply them to their roles:

Interpersonal skills: Senior engineers work more as mentors to other engineers, so understanding colleague problems and questions and working side-by-side with them might be necessary. Principal engineers must motivate many people in different areas and projects from a higher level.
Communication skills: Senior engineers communicate complex technical issues to department management and negotiate with vendors. Principal engineers communicate high-level strategies to their teams and negotiate terms with other firms and individuals in the field.
Innovative and creative skills: Senior engineers must innovate to find solutions for their group's individual projects. Principal engineers review projects across labs and departments to create new theories and determine strategies that others in the field can use.
Leadership skills: Senior engineers lead projects and teams, so they must delegate tasks and evaluate performance. Principal engineers use other leadership skills, such as strategizing, motivating and ensuring all teams receive the appropriate information and guidance.

Management and supervisory roles

Both types of engineers are leaders, but senior engineers often manage one project or department. Principal engineers can oversee larger groups of engineers across labs and projects. Sometimes, principal engineers review staff allocations across projects and move people to different projects depending on resource needs and budget.

Technical knowledge

Both roles specialize in specific engineering fields such as electrical or mechanical engineering and develop technical knowledge through years of experience researching, designing, inspecting and repairing structures or chemicals. Senior engineers apply their technical knowledge to each project by applying principles and theories to each job. Principal engineers still use this knowledge, but they review these principles and theories to further engineering knowledge in the field.