Following the 28% rule, you shouldn't spend more than 28% of your gross monthly income on your mortgage. If you earn $70,000 per year, your gross monthly income is $5,833. This means your monthly mortgage payment should be less than or equal to $1,633. How much house you can afford at $70,000 a year depends on your credit profile, how much you have for a down payment, where interest rates are, and how much your taxes and insurance cost; at a 6% rate with a monthly tax and insurance payment of $400, you might be able to take out a mortgage up to $200,000.