The pre-approval said 510,000 dollars. The borrower who forwarded it to me earned about 95,000 dollars, had a car payment and a student loan, and could not understand how the bank arrived at a number that made her stomach drop. She was not bad at math. She was running different math than the lender. The bank had answered one question, how much it was willing to lend, and she was asking another, how much she could actually live with.
That gap is the whole subject of this guide. We are going to build your borrowing power from the ground up: the income a lender will count, the debts that shrink it, the rate, and the program ceiling that caps it. Then we are going to set that number next to the one that matters more, the payment your real budget can carry. Every lender figure here is dated and sourced, and ceilings vary by loan type, borrower profile, compensating factors, and which underwriting model runs your file, so treat each as a guideline that changes, not a law. At the end you run your own numbers in the home affordability calculator.
How much can I borrow on my income?
It depends on more than income: your monthly debt, your down payment, the rate, and your loan program all move the answer. A common rough anchor is 3 to 4.5 times income with low debt, but that is a starting point, not a quote. A clean file with no other debt lands near the top of that range, and a car loan plus student loans can pull it well below the bottom.
The honest version is that you do not borrow a salary multiple, you borrow against a debt-to-income ratio. Income sets the ceiling, debts lower it, and the rate decides how much loan a given payment buys. So the multiple is a sanity check, not the method.
Borrowing power, defined
Borrowing power is the largest loan a lender’s underwriting will approve based on your income, the debts on your credit report, the interest rate, and the program rules. It is a ceiling for qualification, not the amount you should spend.
What DTI do lenders actually want?
Two ratios do the work. The front-end DTI is your full housing payment divided by gross monthly income, the 28 in the 28/36 rule. The back-end DTI is housing plus every other monthly debt divided by gross income, and it is the one underwriting leans on hardest. Both use gross (pre-tax) income, because that is what lenders use.
Comfort targets sit near 28 percent front-end and 36 percent back-end, but loan programs approve well above that. The figures below are program guidelines that vary by borrower profile, compensating factors, and underwriting model, and they change over time.
| Program | Common back-end ceiling | Source |
|---|---|---|
| Conventional (Desktop Underwriter) | up to 50% (manual 36% standard, up to 45% with credit and reserves) | Fannie Mae B3-6-02 |
| FHA (manual) | 43% base, 47% with one compensating factor, 50% with two or more | HUD Handbook 4000.1 |
| FHA (TOTAL Scorecard) | commonly cited up to about 56.9% for 580+ scores, AUS and lender dependent | HUD / lender AUS |
| VA | no hard cap; 41% guideline plus a residual-income test | VA Pamphlet 26-7 |
The St. Louis Fed found that DTI is the single most common reason lenders cite when rejecting an application, accounting for about 35 percent of all denials in 2024, ahead of credit history and every other factor. The ratio is the binding constraint, which is why every step below is really about moving it.
What counts as income on a mortgage application?
Less than you might hope, and with more conditions. Lenders count income that is stable, documented, and likely to continue, which is why the same paycheck can count fully for one borrower and get haircut for another. This is qualifying income, and it is often smaller than your total earnings.
| Income type | How it is usually counted | Catch |
|---|---|---|
| Base salary or hourly | Counted in full | Easiest to document |
| Bonus, commission, overtime, tips | Averaged, usually over a two-year history | Declining income may be cut or excluded |
| RSUs and stock comp | Two-year history and evidence vesting continues | New grants without history may not count |
| Self-employment (25%+ ownership) | Net profit averaged over two years, after add-backs | Write-offs lower qualifying income |
| Rental income | Typically about 75 percent of gross rent (Fannie Mae) | A 25 percent vacancy and expense haircut |
The two-year rule for variable income
Bonus, commission, overtime, and RSU income generally need a documented two-year history and are averaged, so a great year does not count until it is paired with the year before it. If the trend is down, a lender may average lower or exclude it. Rules vary by lender and program.
What reduces my borrowing power?
Every recurring debt on your credit report, because it eats into the same back-end ratio your housing payment has to fit inside. Car loans, student loans, credit card minimums, personal loans, and required child support or alimony all count. The rule of thumb is blunt and useful: roughly each 100 dollars a month of debt is about 100 dollars a month less you can put toward housing under the same DTI ceiling.
| Monthly debt | Housing budget given up | Rough price impact at 6.49% |
|---|---|---|
| 100 dollars | about 100 dollars | tens of thousands lower |
| 300 dollars | about 300 dollars | around 45,000 dollars lower |
| 500 dollars | about 500 dollars | around 75,000 dollars lower |
| 900 dollars | about 900 dollars | around 120,000 dollars lower |
This is why paying off a car before you apply can do more for your price than a few thousand dollars of extra down payment. If the minimum payments are the problem, the credit card minimum payment trap shows how those minimums quietly drag your DTI.
How do student loans specifically count?
This is where the same borrower qualifies for different amounts at different lenders, because the programs do not agree on how to count a student loan payment. The differences are real and worth knowing before you assume a price.
| Program | How the payment is counted | On a 50k balance, 0 dollar IDR payment |
|---|---|---|
| Fannie Mae | Actual payment, including a documented 0 dollar IDR payment, else 1% of balance | as low as 0 dollars |
| Freddie Mac | Reported payment, else 0.5% of balance if the payment is 0 dollars | about 250 dollars |
| FHA | Greater of the actual payment or 0.5% of balance | about 250 dollars |
| VA | Documented payment, or about 5% of balance divided by 12; may exclude deferral 12+ months | about 208 dollars |
The practical takeaway: before you assume a price, ask the lender which student-loan rule it will use. A borrower with a large balance and a 0 dollar income-driven payment can qualify for noticeably more under Fannie Mae than under FHA, purely because of how the payment is imputed.
Why did I get pre-approved for more than feels comfortable?
Because the lender is solving a different problem than you are. Underwriting optimizes a gross-income ratio and how easily the loan can be sold to Fannie Mae or Freddie Mac. It does not see your childcare bill, your retirement contributions, your travel, your job stability, or the roof that needs replacing in year eight. So the maximum it produces is a qualification ceiling, not a budget.
Spending right up to the approval is how people become house poor, technically able to make the payment while everything else in their financial life gets squeezed. The single most useful sentence here: the bank tells you the most you can borrow, and your life tells you the most you should.
Pre-approval versus pre-qualification
A pre-qualification is an informal estimate from self-reported numbers. A pre-approval uses verified documents and a credit pull, so it carries more weight with sellers. Neither is a spending target; both describe what a lender might allow, not what your budget can carry.
How do interest rates change how much I can borrow?
A lot, because borrowing power is a payment question in disguise. A widely repeated rule of thumb says every 1 percent the rate rises cuts buying power by roughly 10 percent while keeping the same payment. Treat it as a rule of thumb, not a law (worked examples in the sources land between about 10 and 11.5 percent), but the direction is reliable: higher rates shrink the loan a given payment supports.
Rates and borrowing power
As a rule of thumb, every 1 percent increase in the rate reduces how much you can borrow by roughly 10 percent at the same monthly payment. The St. Louis Fed found higher rates push projected payments and DTI up, which is why rising rates drive more denials. Use the current rate, not last year’s.
Borrowing power versus real affordability
These are two numbers with two different owners. Borrowing power belongs to the lender’s model. Affordability belongs to your life. The table below is the difference, and it is also the reason a profitable-looking approval can still leave you stretched.
| Factor | In the lender's math? | In your real budget? |
|---|---|---|
| Listed debts (car, student, cards) | Yes | Yes |
| Childcare | No | Yes, often large |
| Retirement contributions | No | Yes |
| Maintenance and repairs | No | Yes, 1 to 4% of value a year |
| Job or income risk | No | Yes |
| Take-home versus gross | Uses gross | You live on take-home |
For the comfort check, hold the payment against your take-home pay, not your gross. Lenders qualify on gross, but the mortgage is funded from net, after taxes and retirement contributions. If you want the full picture of where the gross goes, take-home pay explained walks through it.
A few worked examples
These are educational illustrations, not approval estimates. They use round numbers and assume a 2026 rate near 6.49 percent for context. The point is to show which limit binds, the front-end housing line or the back-end debt line, because that is what decides your budget.
| Borrower | 28% front-end | 36% back-end minus debts | Binds at | What moves it |
|---|---|---|---|---|
| 6,000 gross, no debt | 1,680 dollars | 2,160 dollars | 1,680 (front-end) | Clean file, housing line sets it |
| 6,000 gross, 400 student loan | 1,680 dollars | 1,760 dollars | 1,680 (front-end) | A stricter program could push it lower |
| 7,000 gross, 650 car plus cards | 1,960 dollars | 1,870 dollars | 1,870 (back-end) | Debt pulls housing below the 28% line |
| 12,000 gross, 700 two cars | 3,360 dollars | 3,620 dollars | 3,360 (front-end) | Strong, but leans on both incomes |
| 16,000 gross, 2,500 heavy debt | 4,480 dollars | 3,260 dollars | 3,260 (back-end) | High income, debt is the constraint |
Two lessons fall out of the table. First, debt, not income, is usually what pulls the budget below the comfortable 28 percent line. Second, when a payment leans on two incomes, model what happens if one stops. A payment that sits at a comfortable back-end ratio on two paychecks can jump past 50 percent on one, which is the real risk of stretching on dual income.
Your next step
Run your real numbers. Open the home affordability calculator, enter your gross income, your actual monthly debts, a local property-tax rate, a real insurance quote, any HOA dues, and the current rate, then read the binding limit it reports. Use the mortgage calculator to see the full PITI and amortization behind the payment.
Then turn borrowing power into a price the careful way. The complete affordability methodology walks the full calculation from income to price ceiling, and the 28/36 rule explained turns the two ratios into real monthly dollars. Borrowing power is the ceiling. Affordability is the floor you actually want to stand on, and it is almost always the lower number.
This is educational information, not a pre-approval and not financial, tax, or legal advice. Mortgage rates, DTI ceilings, income and debt rules, and program guidelines vary by borrower, lender, loan type, credit score, compensating factors, and which underwriting model runs the file, and they change over time. The figures here are illustrative and drawn from the dated sources cited; your numbers will differ. Run your own figures in the calculator and confirm with a lender.