The short answer for $100,000 a year
$100,000 a year is $8,333.33 a month before tax. Under the 28/36 guideline, your full house payment (principal, interest, property tax, insurance and any PMI) stays under 28% of that, which is $2,333.33 a month, and all your debt payments together stay under 36%, $3,000.00.
With no other debts and 10% down at 6.5%, $2,333.33 a month buys about $320,829: $1,825.07 principal and interest, $237.95 property tax, $150.00 insurance and $120.31 PMI. That needs $32,083 down, plus closing costs.
Home price you can afford, no other debt
| Example rate | 5% down | 10% down | 20% down |
|---|---|---|---|
| 6% | $319,517 | $335,246 | $394,241 |
| 6.5% | $305,697 | $320,829 | $376,553 |
| 7% | $292,755 | $307,322 | $360,043 |
| 7.5% | $280,633 | $294,663 | $344,625 |
Putting 20% down instead of 5% raises the price from $305,697 to $376,553, partly because there's no PMI. A rate of 7.5% instead of 6.5% cuts the 10%-down price to $294,663.
With $500 or $1,000 a month of other debt
On $100,000, $500 a month of other debt changes nothing: 36% of your income is $3,000.00, and after the $500 there's still $2,500.00, more than the 28% housing limit of $2,333.33. The prices above still apply. The 36% limit only starts to bind once other debts pass $667 a month. With $1,000 a month of other debt, it leaves $2,000.00 for housing:
| Example rate | 5% down | 10% down | 20% down |
|---|---|---|---|
| 6% | $270,736 | $284,064 | $334,051 |
| 6.5% | $259,026 | $271,848 | $319,064 |
| 7% | $248,060 | $260,402 | $305,075 |
| 7.5% | $237,788 | $249,676 | $292,011 |
How it's worked out
H is the lower of 28% of monthly income and 36% minus other debts, d the down payment share, k = i ÷ (1 − (1 + i)^−360) the monthly payment per dollar borrowed at monthly rate i, t the property tax rate ÷ 12, and PMI = (1 − d) × 0.5% ÷ 12 when you put down less than 20%.
Assumptions you can change in the calculator above: 30-year fixed loan, 0.89% property tax (the US median tax paid ÷ median home value, Census ACS 2024), $1,800 a year insurance, 0.5% a year PMI under 20% down, no HOA. Rates are examples, not today's rates.
Limits
- 28/36 is a cautious guide, not a lender's limit. Fannie Mae allows total debt up to 36% on manually underwritten loans, and up to 45% or 50% in some cases, so you may be approved for more than this.
- It uses gross income, so it doesn't see taxes, childcare or savings goals. A comfortable payment may be lower.
- Property tax and insurance vary widely. Try your state's rate from the mortgage calculator by state.
Other salaries: $40k · $50k · $60k · $70k · $80k · $90k · $120k · $150k · $200k. Know the loan size instead? See the income needed for a $300k mortgage.
Sources
- CFPB: What is a debt-to-income ratio?
- Fannie Mae Selling Guide B3-6-02: debt-to-income ratios (36% maximum for manually underwritten loans, up to 45% or 50% in some cases)
- CFPB: What is private mortgage insurance?
- US Census Bureau, American Community Survey 2024 1-year estimates, table B25077: median value of owner-occupied homes
- US Census Bureau, American Community Survey 2024 1-year estimates, table B25103: median real estate taxes paid
This is an estimate for planning. A lender's pre-approval uses your credit, the loan program and local costs. It isn't financial advice.