A technical interview is a short, slightly artificial conversation meant to answer a practical question: would this person do the work well and be reasonable to work with? You cannot control the interviewers, the questions or the other candidates. You can control how well you prepare and how clearly you show your thinking.
This article is general information. Formats vary between employers, industries and countries, and nothing here guarantees a result.
Know the common formats
Interviews for engineering roles often combine several types. Ask the recruiter what to expect; most are willing to say.
- Screening call. A short conversation to check background, interest and basic fit.
- Technical questions. Verbal questions on fundamentals relevant to the role, such as circuits, materials, statistics, data structures or design basics.
- Problem-solving exercise. A problem worked out on a whiteboard, shared screen or paper. Software roles may involve writing code; other roles may involve estimating, sketching or reasoning about a system.
- Take-home task. A small assignment completed in your own time. Clarify the expected time and how it will be judged.
- Project discussion. A walk through something you have built or worked on.
- Behavioural questions. Questions about how you handled situations with people and pressure.
- Panel or team meeting. A chance for potential colleagues to see how you communicate.
Not every process includes all of these, and some are quite informal.
Prepare the fundamentals
Interviewers usually probe basics for the field in the job description. Reread the advert and list the topics it names, then:
- Refresh core concepts you have not used recently. A quick engineering math refresher or statistics review can help if your numeracy feels rusty.
- Practise explaining each concept out loud in simple terms. If you can explain it to a non-specialist, you probably understand it.
- Be honest about your gaps. Know which areas are weaker and how you would learn them.
- Practise related problems, timed if the interview will be timed, but do not memorise answers. Interviewers tend to notice recitation and often change the question to test understanding.
Learn something about the employer too: what they make or do, and what the role would involve. You do not need to be an expert, but informed questions reflect well on you.
Think aloud
On a problem, the interviewer is often more interested in how you reason than in whether you land on the answer quickly. Silence leaves them guessing, so narrate.
A reasonable pattern:
- Restate the problem in your own words and confirm it.
- Ask clarifying questions. What are the inputs, limits, units and assumptions? What does success look like?
- State your assumptions out loud, and note which ones you would check in real work.
- Outline an approach before diving into details. Mention an alternative and why you chose one.
- Work step by step, saying what you are doing and why.
- Check your result. Test it with a simple case, check the units and ask whether the answer is plausible. Sanity checks and order-of-magnitude estimates are exactly the habits interviewers like to see.
- Discuss limits and improvements. What would you do with more time?
If you get stuck, say so, and say what you are trying. Describing where you are stuck, then trying a simpler version of the problem, is a normal and respectable approach. Many engineers find that explaining a problem aloud helps them see it differently, a technique related to rubber duck debugging. If you make a mistake, notice it, name it and fix it calmly. How you handle an error says a good deal about how you would handle one at work.
It is fine to say “I don’t know, but here is how I would find out.” Bluffing is usually more costly than honesty.
Discuss your past projects
Be ready to talk about two or three pieces of work in some depth. Choose ones where you can explain what was going on and what you personally did.
For each, be able to say:
- The problem and who it was for.
- Your role, clearly separated from the team’s.
- The main decisions, the alternatives you considered and why you chose as you did.
- What went wrong, and what you learned or would change. Honest accounts of setbacks are usually more credible than flawless ones.
- How you knew it worked, such as tests, measurements or feedback.
Do not exaggerate your contribution or claim credit for the work of others; interviewers often ask follow-up questions that reveal this. Respect confidentiality: describe the work in general terms if details are restricted. An engineering portfolio and written project case studies can help you organise these stories beforehand. Behavioural interviews call for a similar preparation of examples about teamwork and conflict, using a structure such as situation, action and result.
Ask good questions
At the end you will usually be invited to ask questions, and this is part of the assessment. It is also your chance to judge whether the job suits you. Ideas include:
- What would a typical week look like in this role?
- How does the team review work and share knowledge?
- What does success look like in the first six months?
- How does the team handle disagreements and mistakes?
- What opportunities are there to learn and develop?
- What are the hardest parts of the job at the moment?
Avoid questions you could have answered by reading the company website, and keep questions about pay and conditions for the moment the employer raises them or an offer approaches, unless you have been invited to ask earlier.
Practical preparation
- Do a mock interview with a friend or mentor, and ask for specific feedback. Engineering mentoring can be a good source of this.
- Prepare your setup for remote interviews: a quiet space, a tested connection and any software you need.
- Plan the journey and arrive early for in-person interviews.
- Bring paper and a pen for notes and sketches.
- Sleep and eat sensibly. Nerves are normal and usually shared by the interviewers’ memories of their own interviews.
Your technical resume should match what you say, so reread it beforehand. Anything on it is fair game.
Afterwards
Send a short thank-you note if that is customary. Write down the questions you found hard, and review them whatever the outcome. Rejection is common and often reflects factors unrelated to your ability, such as the competing candidates or the exact needs of the team. Treat each interview as practice that makes the next one easier, and ask for feedback politely if you think it might be given.