If you're going to your first professional interview, or haven't been to one in a while, you might be wondering how long it will last. You may even wonder things like, is a 30 minute interview good or bad?

The person doing the interviewing will obviously guide the interview and determine how much time it will take. If you're the job candidate, you probably won't know exactly how long the interview will take, but in many cases, the interviewer may not know either. The type of interview may affect its length.

Interview for a Position

Phone interviews can be just as long as in-person interviews. Recruiters frequently use them when speaking with candidates in remote locations. Phone interviews are often shorter, averaging 20 to 25 minutes. Interviewers will most likely arrange an in-person interview before hiring a candidate.

Similarly, screening interviews weed out unqualified candidates through a series of basic questions. They are often held in an office, although they can take place over the phone. These interviews are typically shorter, perhaps 30 minutes or less. They’re very structured and may take place during a tight schedule of other brief interviews. Recruiters will contact the most qualified applicants for a more thorough interview.

Prepare for Longer Interviews

One-on-one interviews take place between the recruiter and the candidate, and they involve more detailed questions. When you think of a job interview, this is likely the type you imagine. A 1 hour interview will usually be a one-on-one interview.

Committee interviews involve more than one interviewer, with each member asking questions. This type of interview is more likely to take longer for two reasons. First, more people have questions to ask at a committee interview; second, the interviewers are probably quite serious about the candidate if they have all taken time out of their schedules to attend.

Recognize Success Signals

A lengthy interview can signal a strong prospect of receiving the job, especially if you sense you have a strong rapport with the interviewer. Never drop your guard in the assumption that you have the job, though. Always continue to give your best answers and stay professional. The interviewer could be trying to get you to relax in order to test your professionalism. If the interview has gone on for an hour or more, you may have a great chance, but the interviewer is still testing you.

Avoid These Mistakes

Don't try to stretch out an interview in the hopes that the more time you spend with the recruiter, the better your chances. A long interview is a sign of success, not necessarily a means of success. Keep your answers straightforward, avoiding long-winded ramblings.

If you get the sense that the interviewer wants to ask another question, or her body language shows she's not engaged, wrap up what you're saying. For example, if she's looking away — or trying to get a word in — you probably need to make your answers more succinct. This is one of the most common interview mistakes to avoid.