A job interview is usually your single best chance to impress a hiring manager enough to get an offer. In some instances, a hiring decision is made immediately and you get an on-the-spot offer. Often, though, it takes days or weeks before you get official word. You may get some indicators of a manager's assessment by watching for cues during and after the interview.
Urgency at the Close
One of the best signs that you made a good interview impression is that the hiring manager or committee is not in a rush to end things. When interviewers don't get a good vibe during the interview, they typically take advantage of the chance to say "that's all the time we have." If you establish good rapport, intrigue the hiring manager with your responses and create a favorable impression, he may either lose track of time or accept the interview going over a few minutes.
Positive Nonverbal Mannerisms
Some hiring managers try to remain stoic or inexpressive during the interview. However, a number of nonverbal giveaways can begin to show as you move toward the end of the interview. Natural smiles, an upbeat tone, leaning in toward you and head nodding are all positive signs that the interviewer is accepting of your answers and feeling your vibe. These signs can certainly be false positives, but you can feel better about these overt nonverbal signs than no reaction at all.
Interviews are often a two-way street. Many interviewers take time before, during and after an interview to give you information on the job as a matter of course. Often, though, interviewers get more persuasive in their efforts to sell you on the company and position if they really want you. This point is especially true in situations where you have great credentials and seek a position in an industry with high job demand. Persuasive efforts at the end of the interview are more revealing given the interview has a sense of whether it is worth the time to pitch you.
Some of the strongest signals come just after the interview. Comments like "we'll definitely be in touch" or "you did a nice job" are more positive than "we'll be in touch" or "we'll let you know either way." Hiring managers may also introduce you to potential colleagues and co-workers spontaneously if you leave a good impression. This isn't necessarily a signal you did well if introductions were planned from the start.