1. United States
In the United States, once you receive your F-1 Visa, which is the one given to international students that will study a full time program in language school, high school, universities and other higher education institutions in that country, you will have the right to work On-Campus for maximum 20 hours per week during the study period and up to 40 hours per week during the vacations period. Working On-Campus implies that the job must be done for the institution you study in, not mattering if it is done inside the facilities of the institution. It also permits to work for the enterprises that provide services for your education institution (like the Cafeteria and Library services). With your F-1 Visa, you will not be able to work Off-Campus unless you ask for the permit of the Immigration Services of the United States. You can do this a year after the beginning of your study and only if you will do an Optional Practical Training (OPT) which is a work related to your field of study, or a Curricular Practical Training (CTP), which is an internship.
2. United Kingdom
If you are going to study in the United Kingdom, you must know that in this country you will be able to work as a student only if you are granted a Tier 4 Visa. This is the visa that is given to international students that are studying in the UK for a period of six months or longer. You must have in mind that the work permit in the United Kingdom will depend on the type of course and institution where you will study. You will only receive a work permit if the program of your interest is taught by an institution funded with governmental funds or an institution allowed to give higher education degrees. The amount of hours you will be able to work, which is maximum 10 or 20 hours per week during the study period, will depend on the type of course you will pursue. During the vacations period, all students with a work permit are allowed to work full time for up to 40 hours per week.
If you decide to work in Australia, the student visa will allow you to work up to 40 hours every two weeks during the study period, and full time while you are on vacations. It is important for you to know that, once you find a job in Australia, your employer must give you a formal award or agreement which should establish the minimum wage you will receive per hour, as well as your working conditions. In Australia, the minimum wage per hour is established by the government. In that sense, depending on the sector where you are working, you should research which is the minimum wage you must receive.
As a student in France you will be able to work both On-Campus and Off-Campus, as long as you have a residency card and you are studying in an institution that gives you access to the Social Security System. Being a student in France, you will have the right to work up to 964 hours during the year, which is equivalent to 60% of the 35 hours per week that are usually worked in the country. During your study period, you will be able to work part-time, while in vacations, you will have the possibility of working full time without exceeding the maximum hours allowed per year. In France, the minimum wage is 9,40 euros per hour. Keep in mind that you will have to pay approximately 20% of your salary on taxes.
In this country you will be able to work up to 120 days per year in a full time work or 240 days in a part-time work. Although in Germany the minimum wage for each hour worked is not established, usually for an hour worked you can receive between 6-10 euros. In case of needing to work more hours, you will have to ask for a special request to the Federal Employment Agency of the state where you are studying, as well as to the migration authorities. You will also be able to work more than the 120 days allowed, if you find a job with the institution you are studying in. However, to do so, you will also have to ask for the permit to the local authorities. In case of been doing a language course in Germany, you will only be able to work during the vacation periods.
In Spain, international students can ask for a work permit to the local authorities, to work up to 20 hours per week. This permit allows the student to work in a company with which the student has signed a part-time work contract. This permit will have the same length of the one of the contract, and cannot be higher than the duration of the student visa. It is important for you to keep in mind that the work you should be performing must be related to the study program you are pursuing in Spain. You will only be able to work full time for up to 3 months during vacation periods.