This is a question that is asked over and over again that is answered with another question – Do you feel tired when you wake up?
If you are consistently waking up tired, then you aren’t getting enough sleep. Ideally, waking up with no alarm (while not sleep deprived) is a good estimate as to how much sleep you need.

Try to following to try and establish how much sleep you need:
Go to sleep when you are tired and wake up with your alarm. You will probably feel groggy but that is to be expected. Continue to go to sleep as soon as you feel tired and eventually, your body will have a certain time that it feels tired compared to your alarm time. The difference is about how much sleep you need.

The amount of sleep depends upon the individual – genetics and daytime activities. It can range from 4 hours to 12 hours so don’t listen to people who say you should get X amount of hours of sleep per night.