In part-time work the working hours are at most 80 per cent of the working hours of a full-time employee applied in the industry.
If you do not know the maximum working hours applied in your job, you can ask your employer. The collective agreement applied is also usually mentioned in the employment contract. You can check the maximum working hours there. If the maximum working hours have not been determined separately, the working hours in accordance with the Employment Contracts Act shall be applied, which are 40 hours a week.