A higher salary changes life: the marginal utility of money.

If your fixed monthly expenses are 5,000 and your salary is 6,000, you can only save 1,000. He earns 30,000 a month and can save 25,000. 30,000 is five times 6,000, but 25,000 is twenty-five times 1,000.

His salary increased fivefold, but his savings grew twenty-fivefold. That's why higher-paid workers can more easily afford to buy a house or a car—the real difference lies here.

So when calculating what it takes to live on a salary, the most important figure is your absolute savings.