Debt-to-Income (DTI) ratio is your total monthly debt payments divided by your gross monthly income.
Let’s assume you are an E-6 over 8 years (base pay of about $3500/month), with housing allowance of $1500/month, and subsistence allowance of $365/month. Your total monthly income is $5365/month.
VA guidelines do not have DTI limits, but as a rule of thumb, most loan officers limit pre-approvals to 50%. So, if you make $5,365/month, you would most likely not be issued a pre-qualification letter with a mortgage payment that exceeds $2,682 minus your other monthly debts.
Those other debts include car payments, student loans (which have special circumstances), credit card minimum payments, boat loans, timeshares, military star card, etc.