The full time person should be paid more if doing more hours. If you consider expenses for transportation and lunchtime, they should receive the same.
The hourly rate should be higher to the part time, because you have to pay the "premium" for hiring only when you need, and specially if the goals are similar between the part time and the full time person.
It's arguably justifiable. There are overhead expenses and other costs that a company has to pay roughly per employee regardless of how much they work. Or at least, that wouldn't cost half as much just because the employee works only half time. In other words, hiring two 20-hour/week employees will likely cost the company more than hiring a single full-time employee.
Part time work is also somewhat higher risk. A part time employee is more likely to stay on for a shorter period of time than a full-time/career employee, so the company may have to absorb the costs of interviewing, hiring, and training new people more frequently in a part-time position.
I've seen a lot of companies distribute the cost by paying part-timers and full-timers the same hourly rate but offering more benefits to full-time employees. I think this is by and large the fair way to do things, since part-timers are more likely to have access to a more comprehensive benefits source from other full-time income (second job or spouse).
Hi Eric thanks for commenting! At my current job, in terms of my education level I know I'm totally being underpaid. But I accepted it because I work part time. Recently I did a search on google and noticed that people with my position even though they work part time, we live in the same city, they're getting paid more than I am. What do you think about that?
Maybe it's time to ask for a raise? I have worked at places where the part time one was compensated more, because of the lack of hours. Life isn't fair, dang it! But I agree with you, full time or part time, the same job, same wage is fair.
Hi Sandy yeah I thought about asking for a raise but I don't think I've worked here long enough! I guess what I should have done was just ask for a higher hourly wage when they asked me at the initial interview. But then I thought I would get rejected if I asked for something higher. Life is so not fair! Thanks for commenting!