Ideal Rent as per Salary

It should be less than 10%

The less the better!

Depends on your salary and family size.

A family of 3 with a 1 lakh/month income will not be able to manage in a place paying 15k as rent.

On the other side, a bachelor tech bro working in big tech, making 5 lakhs/month, won't rent a place for 75k/month.

Every penny you dont pay for rent is a penny saved for something else. Secondly, your rent decides your company and community around you. So your other expenses are anchored to your rent.

For eg: higher rent will mean you are surrounded by people with iPhones, overseas vacations, children studying in international schools demanding imported toys. Your standard of living gets anchored to that. If everyone around you is spending as high as you do, then that high spending doesn't bring special happiness.

However, if your rent is very low and your community is relatively modest, that iPhone feels like a flex for a pretty long time.

Quality of life also matters after some point.

A nice clean soothing room and a very good quality bed and mattress. These do matter in the long run.

Max 20% is ok but after that own a house plan it. Buy it... Increase the income

It depends on how much are you willing to compromise. If you're living alone, outside of your native place, it's better to find a place in sharing. The less you spend is better.