Why Google interviews never last longer than 30 minutes

As a hiring manager, if you are interviewing a job candidate, there is no reason why your interview should take longer than 30 minutes as long as you ask the right questions.

That's the view expressed in a new book co-authored by Google executive chairman Eric Schmidt and former senior vice president of product Jonathan Rosenberg, How Google Works.

“Shortening the interview forces the conversation to be focused,” they say. “There’s no time for idle chit-chat or meaningless questioning. It forces people, including (especially) you, to have substantive conversations.”

Although a job applicant may be interviewed by several Google employees, generally speaking, each interview will last no more than 30 minutes.

Google believes that by the time the interview is about half an hour in, the interviewer should have formed a preliminary impression of the candidate and decided whether to schedule another interview with the candidate. Google interviewers limit themselves to a maximum of five interviews, no matter how important the job opening is.

Of course, there are exceptions.

"Once, in the early days of Google, we interviewed a candidate more than 30 times and still couldn't decide whether to hire him," Schmidt and Rosenberg wrote.

Schmidt and his team decided to follow up on the interview process to make it as efficient as possible.

They found that after one interview, the interviewers were able to make decisions 75% of the time. After four interviews, the interviewers were able to make decisions 85% of the time. Then, their ability to make decisions stopped improving. So they decided to limit the number of interviews to five. Schmidt and Rosenberg joked that computer scientists believe that five is a golden number.

“Remember: From the interviewer’s perspective, the purpose of the interview is to form an opinion. A strong opinion: Do you want this candidate or don’t you want this candidate?” they wrote.