<prompt> Human: My biweekly paycheck is going to be 3000 after taxes. Should I spend 2400 on rent per month? I am a single man, looking for a 1 bed 1 bath in Bay Area and this is how much it costs for a decent apartment here. I dont have a 401k set up yet and I am planning to buy a car soon too. I will be making payments for that as well. I dont have any debts.  <response>: As others noted, it is a bit high although these are just guidelines, not rules.The rule should be that the sum of all your expenses should be less than your net income, so you can actually save money e.g. into your 401k. Say, save at least 10 to 15 of income -- thats what Schwab and Vanguard recommend. 