What is net income for 1 person wich it is enogh to live comfortable?

Well, there are people who earn S$1000 per month and save some of that, and then there are people who have S$20000/month, spend it all and complain it's not enough.
If your definition of "comfortable" includes a rented apartment on your own (not shared with others), a car and savings enough to provide for old age, you need to earn at least S$7000/month. If you smoke, drink or want to travel often, you'll need more.

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