It is somewhat subjective due to your age, abilities, learning style and your other commitments. It is best to consult me or your piano teacher directly. The following is only a rough Minimum recommended guide:
Complete beginner (0-1) years: 12-15 minutes a day. 4-5 days a week.
beginner (1-3 years)/Preliminary to grade 1: 20-25 minutes a day. 5 days a week.
Beginner to low intermediate/grade 2-3: 25minute-35 minutes a day. 5 days a week.
intermediate/grade4-5: 45 minutes-1 hour. 6-7 days a week.
Advanced/grade 6-7: 1h- 1h 20m. 6-7 days a week.
Advanced+/ Grade 8: 1h 15m-2h. 6-7 days a week.
Advanced+/Certificate of performance: 1h 30m-2h 30m. 6-7 days a week.
Other IMPORTANT practice tips:
- It is more about Effective practice not the duration of practice. This is one of the main method, I teach to my students. If you can identity your own mistakes, isolate them and practice it rather than playing through the entire piece.
- Consistent practice is better than 'cramming' practice. For example, it's better to practice 20 minutes every day then 2+ hours in a day on the weekend.
- Duration of practice only helps to an extent. By increasing practice time, any where from 5minute-3 hours of total practice will help you progress faster. However, Practicing for more than 3 hours a day not recommended even if you are on the most advanced level. The efficiency/quality decreases the longer you practice during a day.