5 common mistakes engineers make in technical interviews

Technical interviews are supposed to measure skills. In practice, many strong engineers fail them for reasons that have little to do with raw ability. The most common failures come from how candidates approach the problem, communicate their thinking, and react under pressure.

Below are five mistakes that show up again and again in technical interviews. Avoiding them won’t guarantee a job offer, but it will significantly improve how interviewers evaluate you.

1. Jumping into code too quickly

Sometimes, engineers treat technical interviews like a race. As soon as the problem is presented, they start typing, hoping momentum will carry them through. This instinct is understandable, but it usually backfires.

Interviewers want to understand how you think. The early moments of a technical interview are where they assess problem framing, judgment, and clarity. When you jump straight into code, you skip the part of the interview they're actively scoring.

Rushing also creates avoidable mistakes. Engineers who code immediately often miss constraints, misunderstand inputs, or build a solution that technically works but does not match the problem as intended. Backtracking later costs time and confidence.

Before writing any code, state your understanding of the problem out loud. Summarize the goal in your own words. Outline a high-level approach. Confirm assumptions. A simple explanation of how you plan to solve the problem sets a strong foundation and gives interviewers confidence in your process.

2. Not clarifying the problem

A surprising number of interview failures come down to solving the wrong problem well.

Engineers often assume details that were never specified. They infer input sizes, data formats, performance constraints, or edge cases based on past experience instead of the actual prompt. Once those assumptions are baked into the solution, the candidate may confidently head in the wrong direction.

Interviewers expect clarifying questions. Asking about input constraints, expected output format, edge cases, or tradeoffs is a sign of maturity, not uncertainty. These questions show that you know how real problems behave outside of idealized examples.

Clarifying early saves time later. Spending one or two minutes aligning on constraints can prevent a solution that needs to be rewritten halfway through the interview. It also demonstrates that you value correctness and alignment over speed.

A good rule of thumb is to ask enough questions that you could confidently explain why your solution is appropriate for the given constraints.

3. Treating the interview like a test instead of a collaboration

Many engineers fall into “test mode” during interviews. They go silent, work internally, and surface only a final answer. While this might feel efficient, it makes the interviewer’s job much harder.

Silence deprives interviewers of signal. If they cannot follow your thinking, they cannot assess your reasoning, help redirect you, or understand how you handle uncertainty. Long quiet stretches often read as disengagement or confusion, even when the candidate is thinking productively.

Technical interviews are collaborative by design. Interviewers expect you to think out loud, respond to hints, and treat prompts as part of a conversation. This does not mean narrating every thought. It means sharing decisions as you make them and explaining why you chose a particular direction.

To narrate your thinking without rambling, focus on decisions. Explain what you are choosing to do and why. Skip internal doubts or tangents. Treat the interviewer like a teammate reviewing your approach, not a proctor watching silently.

4. Struggling to explain your thinking clearly

One of the most frustrating outcomes for candidates is hearing feedback like “the solution was correct, but the explanation was unclear.” This happens more often than people expect.

Interviewers evaluate reasoning as much as correctness. If they cannot follow how you arrived at an answer, they cannot assess whether the approach was intentional, repeatable, or accidental. Clear thinking that is poorly communicated often gets scored lower than a slightly weaker solution that is well explained.

Common communication pitfalls include jumping between ideas, skipping steps, assuming shared context, or introducing details before establishing the main approach. These patterns force interviewers to mentally reconstruct your logic, which increases cognitive load.

A simple structure helps. Start by restating the goal. Then explain your approach at a high level. Walk through the key steps. Call out tradeoffs or alternatives briefly. This structure gives interviewers a map they can follow, even if the solution evolves during the interview.

Clarity is a skill, not a personality trait. Practicing explaining your thoughts is one of the highest-leverage ways to improve interview performance.

5. Freezing when the problem feels unfamiliar

Even well-prepared engineers encounter problems they do not recognize. When that happens, many candidates freeze. They stop talking, fixate on finding the “right” pattern, or mentally spiral because the problem does not match something they have practiced.

Interviewers do not expect you to know every solution. What they look for is how you respond when the answer is not obvious. They want to see decomposition, reasoning, and progress under uncertainty.

When a problem feels unfamiliar, start by anchoring to what you do know. Identify subproblems. Explore simpler versions. Ask clarifying questions. Make your reasoning visible. Showing forward motion matters more than landing on a perfect solution.

Recovering well is often more impressive than solving quickly. Candidates who stay calm, adapt, and reason clearly under uncertainty tend to score higher than those who panic or shut down.

Get ready with Formation

At Formation, we help engineers build interview readiness by strengthening fundamentals, practicing how to think and communicate out loud, and getting feedback from senior engineers and hiring managers from top-tier tech teams. 

Our live, interactive workshops are led by mentors who’ve hired, coached, and interviewed at the highest levels, and give you space to practice in real time. You’ll be able to ask questions, pressure-test your answers, and see how interviews actually work today. 

If you want hands-on preparation that builds clarity, adaptability, and confidence over time, explore our upcoming workshops to see what’s coming up next.