Crunch My Mortgage

How much house $50k, $75k, $100k, and $150k can support

A price that fits an income is the price whose full housing payment stays inside the debt-to-income limits you set. The same limits, run at four incomes, do not produce four prices in a straight line.

By Crunch My Mortgage Editorial Team Sources How we test

Gross income is the number people quote. The payment the house requires is the number that has to fit. Lenders turn that fit into ratios. The Consumer Financial Protection Bureau defines a debt-to-income ratio as monthly debt payments divided by gross monthly income, and it says different loan products use different limits. The home affordability calculator does not look up a product. It takes the front-end and back-end caps you type and finds the highest price, rounded down to the nearest $100, whose housing cost still fits the tighter cap. This page runs that function at $50,000, $75,000, $100,000, and $150,000 of gross income. The rate and the tax figure below are inputs to the example. They are not a quote and not a local tax bill.

Two ratios, and the lower one wins

The front-end ratio is the housing payment divided by gross monthly income. Housing here means principal and interest, property tax, insurance, association dues, and mortgage insurance when the loan is large relative to the price. The back-end ratio adds the other monthly debts the lender counts: a car payment, a student loan, the minimum on a card, support that is included. It is housing plus those debts, divided by the same gross income.

A household can clear one cap and miss the other. If other debts are small, the front-end cap is often the one that stops the price. If other debts already use a large share of income, the back-end cap stops it first, and raising the front-end number does nothing. The calculator uses the lower of the two housing budgets. Gross income is pay before taxes. The amount that reaches a bank account is smaller, so a ratio that meets a published cap can still be tight on take-home pay.

The down payment changes the loan, and the loan changes both the principal-and-interest payment and whether mortgage insurance is charged. In this calculator, mortgage insurance is applied when the loan is over 80 percent of the price. A larger pile of cash for the down payment can remove that line and raise the price that fits. Cash that is spent on the down payment is cash that is not available for closing costs, which are a separate total.

What Fannie Mae and FHA publish

Fannie Mae’s Selling Guide, section B3-6-02, sets a maximum total debt-to-income ratio of 36 percent of stable monthly income for a manually underwritten loan. That maximum can go to 45 percent when the borrower meets the credit-score and reserve requirements in Fannie Mae’s Eligibility Matrix. For a loan casefile underwritten through Desktop Underwriter, the maximum allowable ratio is 50 percent. The same section lists transactions with a different ceiling, including some cash-out refinances, high-LTV refinances, loans without a credit score, and loans with a non-occupant borrower. A conventional lender can also apply a tighter test than Fannie Mae’s ceiling. The guide says a more conservative approach is acceptable when the lender applies it consistently.

FHA’s Handbook 4000.1, in the manual-underwriting section last revised August 12, 2026, uses two ratios: the total mortgage payment to effective income, and the total fixed payment to effective income. The approvable-ratio chart starts at 31/43. Borrowers with a minimum decision credit score below 580, or with no credit score, may not exceed 31/43, except that energy-efficient homes may use 33/45. At 580 and above, 31/43 needs no compensating factor. The same chart allows 37/47 with one listed factor, 40/40 when there is no discretionary debt, and 40/50 with two listed factors. Those factors are cash reserves, a minimal increase in the housing payment, residual income, and, for the 40/50 band, significant additional income that is not already in effective income. A loan run through FHA’s TOTAL Mortgage Scorecard is underwritten under a different part of the handbook. This page does not treat the manual chart as that automated decision.

Neither chart is a price. A ratio limit becomes a price only after a rate, a term, taxes, insurance, and a down payment are applied. Change any of those and the price moves, even if the income and the ratio stay put. The debt-to-income calculator starts from a payment you already have and reports the ratios. The affordability calculator starts from the ratios and searches for a price.

What this example types in

The four runs share one set of inputs so the income is the thing that changes. The front-end cap is 28 percent. The back-end cap is 36 percent. Other debts are $350 a month. Cash available for the down payment is 20 percent of that run’s annual income, not 20 percent of the price. The note rate typed in is 6.5 percent, the term is 30 years, property tax is typed as 1.1 percent of the price per year, insurance is $1,400 a year, and there is no association due. Mortgage insurance is typed as 0.5 percent of the loan per year, and it is charged only while the loan is over 80 percent of the price.

The 28/36 pair is inside Fannie Mae’s 36 percent manual ceiling and tighter on the front end than FHA’s 31 percent starting line. It is not those ceilings. Someone using the calculator can type 31 and 43, or 36 and 45, or any other pair the situation calls for. The prices below are what this function returns for this pair. They are not an approval, and they are not the most a program will allow.

Worked example

Each income is gross and annual. Monthly income is that figure divided by 12. The housing budget is the lower of the front-end cap and the back-end cap after the $350 debt. The price is the highest hundred-dollar price whose full housing cost is still inside that budget.

  1. $50,000 a year. Monthly income $4,166.67. Front-end room $1,166.67. Back-end room after debts $1,150.00. The back-end cap is the one that binds, so the housing budget is $1,150.00. With $10,000 for the down payment, the calculator’s price is $143,800. The loan is $133,800 (7% down). Principal and interest $845.71, tax $131.82, insurance $116.67, mortgage insurance $55.75. The full housing payment is $1,149.94, which is 27.6% of monthly income on the front end and 36.0% on the back end once the $350 debt is included.
  2. $75,000 a year. Monthly income $6,250.00. Front-end room $1,750.00. Back-end room after debts $1,900.00. The front-end cap is the one that binds, so the housing budget is $1,750.00. With $15,000 for the down payment, the calculator’s price is $226,500. The loan is $211,500 (6.6% down). Principal and interest $1,336.82, tax $207.63, insurance $116.67, mortgage insurance $88.13. The full housing payment is $1,749.24, which is 28.0% of monthly income on the front end and 33.6% on the back end once the $350 debt is included.
  3. $100,000 a year. Monthly income $8,333.33. Front-end room $2,333.33. Back-end room after debts $2,650.00. The front-end cap is the one that binds, so the housing budget is $2,333.33. With $20,000 for the down payment, the calculator’s price is $307,200. The loan is $287,200 (6.5% down). Principal and interest $1,815.30, tax $281.60, insurance $116.67, mortgage insurance $119.67. The full housing payment is $2,333.23, which is 28.0% of monthly income on the front end and 32.2% on the back end once the $350 debt is included.
  4. $150,000 a year. Monthly income $12,500.00. Front-end room $3,500.00. Back-end room after debts $4,150.00. The front-end cap is the one that binds, so the housing budget is $3,500.00. With $30,000 for the down payment, the calculator’s price is $468,400. The loan is $438,400 (6.4% down). Principal and interest $2,770.99, tax $429.37, insurance $116.67, mortgage insurance $182.67. The full housing payment is $3,499.69, which is 28.0% of monthly income on the front end and 30.8% on the back end once the $350 debt is included.

The four prices do not move in a straight line with the four incomes. The down payment grows with income, but it is a fixed dollar amount when the price is searched, so the loan-to-value ratio is different in each row. Mortgage insurance turns on only above 80 percent of the price, which puts a step in the housing cost. The cap that binds can switch too. On the $50,000 run, $350 of other debt is a large share of income, and the back-end cap is the one that binds. On the three higher incomes that same debt is a smaller share, and the front-end cap binds. From $50,000 to $100,000 the income doubles. The price does not land on twice the lower result, because the down payment, the flat insurance premium, mortgage insurance, and the binding cap do not all scale with income.

What the price leaves out

The figure is a housing payment that fits the caps. It is not the cash required on closing day. Closing costs, prepaid interest, and the escrow deposit sit on top of the down payment, and a seller credit or earnest money already paid changes the cash. The cash to close calculator adds those lines. A price the income supports can still fail if the cash is not there.

Taxes and insurance in the example are typed, not looked up. A higher tax rate or a higher premium lowers the price that fits, because those dollars come out of the same housing budget as principal and interest. Association dues do the same thing. The rate is an input: a higher note rate buys less price at the same payment. Nothing on this page fetches a market rate.

Reserves, credit history, the property, and the program’s own rules sit outside the formula. Fannie Mae’s 45 percent and 50 percent ceilings depend on the underwriting path and, for the manual loan, on the Eligibility Matrix. FHA’s bands above 31/43 depend on the compensating factors the handbook lists, and on whether the loan is manual or scored. A calculator that is given 28 and 36 will not apply those higher bands on its own. Type the caps that match the rule you are reading if you want the price under that rule.

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