System design interviews test estimation skills, not precise calculations.

A DEV Community article argues that system design interviews evaluate how candidates think, not their ability to provide exact numbers. It states interviewers use scale estimation questions to assess how a candidate handles incomplete specifications, which mirrors real-world engineering work. The piece advises candidates to verbalize their assumptions and calculations to invite collaborative correction from the interviewer. It concludes that demonstrating a structured, communicative approach to estimation is more valuable than silently arriving at a final figure.