Your monthly housing costs should not exceed 29% of your gross monthly income for an FHA loan. Total housing costs often lumped together are referred to as PITI.
P = Principal
I = Interest
T = Taxes
I = Insurance
Monthly Income x .29 = Maximum PITI
$3,000 x .29 = $870 Maximum PITI
Your total monthly costs, or debt to income (DTI) adding PITI and long-term debt like car loans or credit cards, should not exceed 41% of your gross monthly income.
Monthly Income x .41 = Maximum Total Monthly Costs
$3,000 x .41 = $1,230
$1,230 total - $870 PITI = $360 Allowed for Monthly Long-Term Debt