Home Affordability Calculator

Mortgage affordability is not a single number; it is the smaller of two separate debt-to-income tests applied to your gross monthly income. The front-end ratio, sometimes called the housing ratio, measures the proposed monthly housing payment (principal, interest, taxes, insurance, HOA dues, and mortgage insurance, collectively PITI) against gross monthly income. The back-end ratio, also called the total debt-to-income ratio, adds every other recurring monthly obligation on your credit report, including car payments, student loans, credit card minimums, and personal loans, and measures that combined total against the same gross income figure.

Conventional guidelines commonly cited are 28% front-end and 36% back-end, often written as 28/36. FHA loans typically allow up to roughly 31/43, and can stretch further with strong compensating factors such as reserves or a high credit score. VA loans do not enforce a strict front-end ratio and instead rely primarily on residual income analysis alongside a back-end guideline near 41%, though many VA lenders will still underwrite comfortably above that with automated underwriting approval.

The lender computes the maximum PITI allowed under each ratio and then takes the more restrictive of the two, because both constraints must be satisfied simultaneously. If your monthly gross income is $9,167 (equivalent to $110,000 per year), a 28% front-end limit allows a PITI of $2,567. If you already carry $450 of monthly debt, a 36% back-end limit allows total obligations of $3,300, leaving $2,850 for housing after subtracting the $450. In this example, the front-end test is more restrictive at $2,567, so it becomes the binding constraint and the back-end ratio never gets close to its ceiling.

Once the maximum PITI is known, the calculator works backward to a home price. It solves iteratively for the price at which principal and interest (based on your rate, term, and the loan remaining after your down payment) plus property taxes (as a percentage of price), insurance, HOA dues, and private mortgage insurance, if applicable, together equal the maximum PITI. That price, not a multiple of income, is the actual affordability ceiling, because taxes and insurance both scale with price and eat into the housing budget as price rises.

This structure explains why two buyers with identical income can qualify for very different prices. A buyer in a low-property-tax state with no HOA and a 20% down payment (avoiding PMI) will qualify for meaningfully more home than a buyer with the same income facing a 2% property tax rate, a $300 monthly HOA fee, and only 5% down.

Consider a household with $110,000 gross annual income, $450 in monthly debts, a $40,000 down payment, a 6.75% rate on a 30-year fixed loan, a 1.2% property tax rate, $1,600 annual homeowners insurance, no HOA dues, and 0.6% annual PMI if the loan-to-value exceeds 80%.

Monthly gross income is $9,166.67. At a 28% front-end limit, the maximum PITI is $2,566.67. At a 36% back-end limit, the maximum PITI is ($9,166.67 x 0.36) minus $450 debts, which is $2,850. The front-end ratio is binding at $2,566.67, so that is the housing budget the calculator uses to size the price.

Working backward, a $2,566.67 PITI at these tax, insurance, and rate assumptions supports a home price in the neighborhood of $370,000 to $385,000, depending on exactly how PMI phases out as the loan-to-value crosses 80%. The exact figure requires iteration because property tax and PMI both depend on price, which is why this calculator solves it numerically rather than with a single closed-form formula.

Now suppose the same buyer raises their down payment to $76,000, pushing the loan-to-value below 80% at the solved price and eliminating PMI entirely. The freed-up PMI dollars flow directly into principal and interest capacity, typically raising the maximum price by an amount larger than the extra cash put down, because that cash also reduces the loan itself. This is why crossing the 80% LTV threshold is one of the highest-leverage moves a buyer can make to increase purchasing power.

Finally, suppose this buyer wants to know the income required to afford a specific $450,000 target price rather than solving for the maximum price their current income supports. The calculator reverses the process: it computes the PITI required to carry $450,000 at the given rate, tax rate, insurance, HOA, and PMI assumptions, then divides that PITI by 28% to get the front-end-required income and separately computes the back-end-required income by adding monthly debts before dividing by 36%, and reports the larger (more restrictive) of the two as the income actually needed.

Whether the front-end or back-end ratio binds depends almost entirely on how much non-housing debt the borrower already carries. A borrower with no car payment, no student loans, and no credit cards will almost always be constrained by the front-end ratio, because the back-end limit has essentially the full 36% (or 43% for FHA) available for housing once nothing has been subtracted for other debts.

A borrower with significant existing debt, such as $900 per month in student loans and a car payment, will often find the back-end ratio binds first, because that debt eats directly into the 36% ceiling before housing is even considered. In that scenario, paying off or paying down a debt (especially one with a high required minimum payment relative to balance, such as a credit card) can increase housing affordability far more effectively than saving for a larger down payment, dollar for dollar.

FHA loans widen both limits relative to conventional (31% front-end, 43% back-end) which is why FHA is often the path that qualifies otherwise-marginal debt-to-income profiles, at the cost of upfront and ongoing mortgage insurance premiums that are typically higher and harder to remove than conventional PMI.

Lenders will also allow ratios above the stated guideline when automated underwriting systems (Desktop Underwriter for Fannie Mae, Loan Product Advisor for Freddie Mac) approve the file based on compensating factors: significant cash reserves after closing, a credit score well above minimums, a low loan-to-value, or residual income well above regional benchmarks. It is common in the mid-2020s market to see approved back-end ratios of 45% to 50% on strong files, which is materially higher than the textbook 36% figure most calculators default to.

Property tax rates vary enormously across the United States, from effective rates below 0.3% of assessed value in Hawaii to above 2.0% in parts of New Jersey, Illinois, and Texas. A buyer comparing a $400,000 home in a 0.5% tax jurisdiction to an identical $400,000 home in a 2.2% jurisdiction is comparing a $167 monthly tax bill to a $733 monthly tax bill, a difference large enough by itself to change the maximum affordable price by tens of thousands of dollars.

Homeowners insurance premiums have risen sharply in much of the country since 2021, particularly in states exposed to wildfire, hurricane, or severe convective storm risk. Annual premiums of $3,000 to $6,000 are no longer unusual in parts of Florida, Louisiana, and California, versus $1,000 to $1,500 in lower-risk inland markets. Because insurance is a fixed dollar add to PITI regardless of loan balance, high-premium markets compress affordability at every income level.

Private mortgage insurance applies to conventional loans with less than 20% down and typically costs 0.3% to 1.5% of the loan amount annually depending on credit score and loan-to-value, generally dropping off automatically once the loan amortizes to 78% LTV. FHA mortgage insurance premiums (an upfront premium plus an annual premium, currently 0.55% for most 30-year loans with the standard down payment) usually last for the life of the loan unless the borrower puts at least 10% down, which is a meaningful long-term cost difference worth modeling explicitly rather than assuming FHA and conventional PMI are interchangeable.

HOA dues are easy to overlook because they do not appear on a mortgage rate sheet, but they are treated exactly like housing debt in both the front-end and back-end ratio calculations. A $400 monthly HOA fee, common in many condominium developments and some planned communities, consumes the same qualifying capacity as roughly $65,000 to $75,000 of additional loan principal at a mid-6% rate, which is why condo buyers are frequently surprised that their maximum purchase price is lower than a single-family buyer with identical income.

Run the calculator with your actual credit-pulled monthly debts, not an estimate. Lenders use the minimum payment shown on the credit report for revolving accounts and the scheduled payment for installment loans, including any debt with more than 10 months of payments remaining (rules vary slightly by loan program), so a debt you consider nearly paid off may still count in full against your ratio.

Use a realistic property tax rate for the specific city or county you are shopping in, not a national average. Tax rates can differ by more than a full percentage point between adjacent towns in states with fragmented local taxing districts, and that single input change often moves the calculator's maximum price by 5% or more.

Model the effect of a slightly larger down payment before assuming you cannot afford more home. Because crossing the 20% down payment threshold removes PMI entirely, adding even $10,000 to $15,000 of down payment near that threshold can unlock more purchasing power than the raw dollar amount suggests.

Treat the back-end limit as the one most within your control in the near term. Paying off a car loan or consolidating credit card balances in the months before applying can shift the binding constraint from back-end to front-end and materially raise the qualifying price, often faster than saving an equivalent amount toward a down payment.

Remember that qualifying for a payment and being comfortable with a payment are different questions. Lenders will approve back-end ratios up to 45% or higher with compensating factors, but a household carrying that much of its income in fixed obligations has little room for savings, retirement contributions, or unplanned expenses. Many financial planners recommend keeping total housing costs closer to 25% of gross income, below what the lender will actually allow, particularly in markets with volatile insurance costs.

Use the required-income output to reverse-engineer a savings and career plan when a target home price exceeds current qualifying income, rather than assuming the gap is unbridgeable. Knowing precisely how much additional income (or debt reduction, or down payment) is needed turns an abstract goal into a concrete, trackable target.