Do professors get paid for supervising PhD students / honours student's projects?
If so, typically how much?
In the US, supervising graduate students is generally considered part of the normal workload of a faculty member and there's no extra pay for doing this.
The number of students supervised is typically a factor in tenure, promotion, and pay raise evaluations. Not supervising enough graduate students can hurt your evaluations and might possibly result in your not getting tenure or promotion or a pay raise.
Although professors are not technically paid for this work in the US, in many cases they are effectively paid for doing so, particularly for Ph.D. students. This is because in many cases, the professor requires grants in order to be able to hire Ph.D. students to work for them, and those same grants pay for a portion of the professor's time, some of which is expected to be used for supervising the student. The accounting is often rather obscure, however...
In Germany, you may get a little personal bonus (on the order of 100 EUR), which does not flow into the research group budget, per bachelor's, master's or Ph.D. dissertation you supervised. The bonus is usually contingent on reviewing it on time after receiving the official version. This practice may vary from university to university.
Another answer from Germany: Supervising students (BSc, MSc or PhD) is part of the job. No extra salary in general but, as part of the usual negotiations, one may get a temporary raise for "outstanding efforts in supervision".
At my university supervision of students can cover some of your teaching load (e.g. supervising one BSc thesis in math is equivalent to 0.3 hours teaching per week, an MSc thesis is 0.6 hours per week, each thesis counts for the semester in which it is submitted, its capped at 1.8 hours if I remember correctly). However, supervising PhD students does not give anything since PhD students in Germany do not count as students and even teaching at a PhD level does not count for the teaching load.
[As an external advisor,] I got paid for supervising a few masters & bachelors thesis. If I would be a professor or other direct employee of the university, then that would be included in the normal teaching duties for their usual salary, but external supervisors from other universities, research institutes or the industry, as well as external reviewers get separate compensation. The amounts aren't large though, if you put reasonable effort in it then it comes up to a rather tiny hourly rate.
It depends on the work contract between the prof and the University, and in most cases is it highly private data. In the academical sphere I know, they have a base wage, and they get a minimal bonus for the similar things as per-student "services". The most part of their wage comes from the first, despite most of their work is highly student-specific.
I think, it differs highly on other parts of the world (probably even there is big difference between different Universities of the same city).
A grad student costs X dollars. This pays tuition, stipend benefits. The grad student eventually stops taking classes, the new cost of the student is X-T. (T is cost of tuition). Now if the professor still has X coming in (through grants and other funding sources) and the student only costs X-T, there is T left over that neither school nor student needs.
Source- Prof*** at Univeristy of ***