Is the teenager in high school? University? Does the teenager have any working experience? What country is this in? What city?

Not nearly enough information to give any kind of estimate, and even with that information, the answer would probably be "it varies" or "whatever you can negotiate".

Edit: Here is some data from University of Waterloo you might find useful - http://www.cecs.uwaterloo.ca/employers/salary.php

Students alternate between school and work terms, so as you slide up the work term levels it will be for students with more academic and internship experiences.

Highschooler with previous internship experience.

Free. An internship is used to prove one's self. If it's remote relocation, then you should offer to pay their moving expenses (if any). Usually, however, internships in development are time-limited, and you may need to check IRS regulations recently passed regarding internships.

You should note that there exist paid internships in addition to free internships, and that there are strict federal legal criteria of both. See page 8 of the following PDF: http://wdr.doleta.gov/directives/attach/TEGL/TEGL12-09acc.pd...

Statistics have shown that many employers may illegally be using interns as free labor. A while back, the New York Times published an article on the topic: http://www.nytimes.com/2010/04/03/business/03intern.html

My point is that I don't understand why you assumed that the internship I talk of should be free. You didn't hear enough of the details to make a proper legal stance on the issue, and more often than not employers are not paying interns when they should be.

I see your point, but please reconsider what you wrote.

My first job was in IT and would have been an internship if the company regularly hired people (it didn't, this was a special case because of family connections). It was during the summer in high school and paid $10/hour.

In college I had a part-time job doing computer repair/maintenance for a small office at $12.50 an hour, and later had a formal internship at a Fortune 500 company that paid $19.50 an hour

All this took place in the greater Seattle area.

Unless there is a compelling reason to work for free (e.g., difficult industry to break in to, extreme desire to work for said company) I would advocate never working for free if you can get paid. Everyone I've known who worked free as an intern (3 people, perhaps not a large enough sample) were treated unacceptably relative to the atmosphere of a professional office. One basically became 12 people's gopher, filling out uninteresting paperwork and rarely learning anything that added value to their ability to work.

In addition, being paid to work puts one in a position to learn to manage their own finances, if only in part. For me this was easily more important than all the technical skills I picked up.

This is an insulting question. The intern's age does not matter. What are his or her skills, and how much would you pay an adult to do the same thing?

I was making just over $30/hr my freshmen year of college doing engineering/design work. It went up from there until my senior year when I switched to helping start-ups.

Had one friend who his senior year was making an average of $50+/hr. He was doing 80+ hrs/wk so the overtime, double-time, and weekend-time really added up.

The reasonable salary is what the market can bear. If you receive an offer for X, then you need to evaluate if you can make more money elsewhere or if your time is worth more. Make your decision accordingly.

Probably somewhere in the neighborhood of $10/hr, but that depends on area, exact duties of the internship, etc. But, basically, something that covers gas money and incidentals.

My school requires internships. I don't know anyone being paid under $15/hr, and I know a few that are $25+/hr

Edit: Also, Boston area.