While there are no specific rules as to when you might be offered a job after an interview, there are some typical time frames. An interview process can have several rounds, to eliminate candidates and narrow the list, and you could be offered a job at any point along the way. Interviews can start right after an application is submitted or a resume is sent to the employer. If you don't receive an offer, it is appropriate to follow up and check on their decision. To be adequately prepared, expect that you could hear if you got the job at any of these points.
On the Phone
Some employers use phone interviews as part of their screening process. In this situation, it is possible to be offered a job while on the phone with the employer. Positions that are plentiful or need to be filled quickly could be handled this way, such as temporary jobs for a convention or exhibition. Independent contractor jobs or those that are filled remotely can also be offered immediately after an interview on the phone.
After One Interview
The traditional interview process involves at least one in-person meeting with the employer. If an employer thinks you're perfectly suited for a position, you may be given an offer on the spot. Another situation in which a job could be offered immediately is when there are few candidates or they need someone to start right away. For example, some entry-level retail jobs may be filled in this manner.
On Their Schedule
The most typical time to receive a job offer after the interview is within days or weeks after the interview itself. During the interview, an employer might even hint at the length of time she needs to make a decision. Anywhere from a few days to a week or more should be expected. Don't panic if you haven't received an offer by the exact day the company said it would be ready because it is not unusual for employers to need a little more time to make a decision.
After Several Interviews
Some employers will make an offer to a candidate after the second interview, or maybe even after multiple interviews. Higher-level positions can have multiple interview rounds that entail waiting until the process is completed for an offer. After several interviews, the employer likely has narrowed the field to just a few candidates. Because there are fewer choices, you may get an offer or turned down within a few days after multiple interviews, or it could still take weeks. In most interview situations, reference and background checks may need to be conducted, and this could slow down receiving an offer as well.