Mortgage Affordability Calculator

SettingsSettings for this calculationUS

Market

Imperial · sales tax

Gross annual income

Household income before tax.

Include both applicants where the mortgage is joint. Lenders treat variable income — bonus, commission, self-employment — more cautiously than salary, often averaging it over two or three years or discounting it.

Other monthly debt payments

Car finance, loans, card minimums, child maintenance.

Everything a credit check will show. Card balances count at their minimum payment, not their balance. Student loans count in most markets, though the treatment varies.

Debt-to-income limit (%)

The share of gross income the lender allows for all debt.

43% is the common ceiling for a US qualified mortgage; some products stretch to 50%. UK and Australian lenders assess differently — against a stressed rate and a spending assessment rather than a flat ratio — so treat this as a screening figure, not their answer.

Interest rate (% per year)

The rate to test affordability at.

Test at a rate above the one you are offered. Lenders do — a stress test at two or three points higher is standard, and running it yourself tells you whether the payment survives a reversion.

Term (years)

Mortgage term.

The term you would actually take, because it changes what you can borrow and not only what you repay: a longer term lowers the monthly payment, which raises the loan a debt-to-income limit allows. Twenty-five years is the common default; thirty and thirty-five are widely offered and buy a larger loan at a materially higher total cost. Lenders also cap the term at a stated age, so a long term taken late is often shortened by the lender rather than by you.

Available for the mortgage

$2,288

Medium confidence

Figures that depend on a rate wait for yours — this page does not assume one.

Monthly income: $6,250
Total debt allowance at the stated DTI: $2,688
Other debts consuming allowance: $400

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

Debt-to-income limits: US conventional underwriting commonly caps total DTI at 43-50%; UK and AU lenders assess affordability against stressed rates under FCA MCOB 11 and APRA guidance
The DTI limit is a user input here because it varies by lender, product and jurisdiction

Inputs used

Gross annual income: 75000
Other monthly debt payments: 400
Debt-to-income limit (%): 43
Interest rate (% per year)
Term (years): 25

Intermediate steps

Monthly income: $6,250
Total debt allowance at the stated DTI: $2,688
Other debts consuming allowance: $400

Final result$2,288

What this calculation does not cover

A screening figure. Real underwriting also weighs credit history, employment stability, deposit source and the property itself.
UK and Australian lenders assess against a stressed rate and a detailed spending review rather than a flat debt-to-income ratio, so this will not reproduce their answer.
Excludes property tax, insurance and service charges, which some lenders include inside the ratio.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations2

Debt-to-income limits: US conventional underwriting commonly caps total DTI at 43-50%; UK and AU lenders assess affordability against stressed rates under FCA MCOB 11 and APRA guidance
The DTI limit is a user input here because it varies by lender, product and jurisdiction

Cite this page

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Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

How to calculate mortgage affordability in 6 steps

Gross annual incomeHousehold income before tax.

Other monthly debt paymentsCar finance, loans, card minimums, child maintenance.

Debt-to-income limit (%)The share of gross income the lender allows for all debt.

Interest rate (% per year)The rate to test affordability at.

Term (years)Mortgage term.

Loan supportedThe tool computes the loan supported from those figures and shows the formula, its sources, and a confidence rating alongside it.

Frequently asked questions

Why does clearing a car loan raise what I can borrow so much?

Because the debt allowance is a fixed share of income, and every pound of other debt payment comes straight out of it. At 5% over 25 years, removing a 400 monthly payment frees roughly 68,000 of borrowing — far more than the outstanding balance on most car finance.

Should I test at the rate I have been offered?

Test above it. Lenders stress-test at two to three points higher precisely because rates move, and a payment that only works at the offer rate is a payment that fails on reversion. If it still works at the stressed rate, the loan is genuinely affordable.

Why does this not match my lender's figure?

Because a flat debt-to-income ratio is a screening tool, not underwriting. Real assessment weighs credit history, how long you have been employed, where the deposit came from, and — in the UK and Australia — a detailed review of actual spending. This tells you the shape of the answer, not the answer.

Does a bigger deposit change what I can borrow?

It changes what you can buy, not usually what you can borrow. The loan is capped by income; the deposit adds to it. A larger deposit also moves you into a lower loan-to-value band, which usually buys a better rate — and a better rate does raise the loan this calculator supports.