Mortgage affordability calculator

Enter your income, debts, deposit and rate, and see the highest home price each lending rule allows and which rule stops you first.

Each country option uses the figures its regulator publishes. Custom uses the limits you type.

Before tax. In France, net income before income tax.

Car, card, student and personal loan payments.

The cash you can put toward the price.

The rate on the offer, before any buffer.

The number of years the loan runs.

Share of monthly income for the mortgage payment and housing costs. 0 leaves it off.

Share of monthly income for housing plus every other debt. 0 leaves it off.

The most a lender lends as a multiple of yearly income. 0 leaves it off.

Percentage points added to the rate for the payment test.

The payment test uses at least this rate. 0 leaves it off.

Settings

Optional. Steady income a lender counts, such as rent or a pension.

Optional. Counted as a housing cost each month.

Optional. Counted as a housing cost each month.

Optional. Heating, condo or HOA fees, or borrower insurance in France. Canada counts half of condo fees.

Maximum home price

0.00

The largest loan every rule allows, plus the deposit.

Maximum loan
0.00
Monthly payment on that loan
0.00
Which rule sets the limit
-
Rate used for the payment test
0.00%
Payment at the qualifying rate
0.00
Other housing costs a month
0.00
Housing costs as a share of income
0.00%
All debts as a share of income
0.00%
Loan as a multiple of income
0.00

Your data stays in your browser. Nothing is uploaded.

For information only, not financial, tax or legal advice.

Last updated . Method checked . Methodology

This calculator works out how much you can borrow and the highest home price that fits a lender's rules. Enter your yearly income, the payments on other debts, your deposit, the mortgage rate and the term. Pick a country's rules or type your lender's own limits. Canada uses the CMHC debt service ratios of 39% and 44% at a qualifying rate. The UK option shows 4.5 times income, the level from which a loan counts as high loan to income. France applies the 35% debt ratio and the 25 year term limit, and Australia adds a 3 point buffer to the rate. The result names the rule that sets the limit and lists what every rule allows. A lender also looks at your credit file, spending and job, so the figure is a starting point to compare with an offer. The sums run on your device, and no income or debt figure you enter leaves it.

How to use the Mortgage Affordability Calculator

  1. Pick the lending rules for your country, or Custom to type the limits a lender gave you.
  2. Enter your income a year, your other debt payments a month and the deposit you have saved.
  3. Enter the mortgage rate and the term in years. Tip: In Canada and Australia the payment test uses a higher rate than the offer, so the loan comes out lower than the rate alone suggests.
  4. Open the settings to add other income, property tax, home insurance and other monthly housing costs.
  5. Read the maximum price, the rule that sets it and the table of every rule's limit.

Worked example

A buyer with a lender that allows 28% of income for housing and 36% for all debts. All figures are USD.

InputValue
IncomeUSD 90,000.00 a year (USD 7,500.00 a month)
Other debt paymentsUSD 500.00 a month
DepositUSD 40,000.00
Mortgage rate and term6.5% over 30 years (360 monthly payments)
Lender limits28% for housing, 36% for all debts
 
Monthly income = 90,000 / 12 = USD 7,500.00
Housing limit = 28% x 7,500 = USD 2,100.00 a month for the mortgage payment
Total debt limit = 36% x 7,500 = USD 2,700.00, less 500.00 of other debts = USD 2,200.00 a month
The housing limit is lower, so it sets the payment at USD 2,100.00
Monthly rate r = 6.5% / 12, n = 360. The payment on 1 of loan is r x (1 + r)^n / ((1 + r)^n - 1) = 0.00632068
Maximum loan = 2,100.00 / 0.00632068 = USD 332,242.72
Maximum price = 332,242.72 + 40,000.00 = USD 372,242.72
Maximum home price
USD 372,242.72
Maximum loan
USD 332,242.72
Monthly payment on that loan
USD 2,100.00
Which rule sets the limit
Housing costs (front ratio) sets the limit.

The total debt limit alone would allow a payment of USD 2,200.00 and a larger loan, so the lower of the two applies. The loan is rounded down to the cent so its payment never passes the limit.

How the maximum loan is calculated

Monthly income I = (income + other income) / 12
Housing payment allowed = I x front ratio - housing costs
Debt payment allowed = I x back ratio - other debts - housing costs
Test rate q = the greater of (rate + buffer) and the minimum qualifying rate
Loan for a payment M = M / (q' x (1 + q')^n / ((1 + q')^n - 1)), where q' is q per month
Loan by income multiple = yearly income x multiple
Maximum price = the lowest loan of the active rules + deposit

Each active rule gives its own maximum loan. A ratio rule takes a share of monthly income, removes the other housing costs (and, for the total debt ratio, the other debt payments) and leaves the most the mortgage payment can be. That payment is turned into a loan with the standard payment formula run backward at the test rate over n monthly payments. An income multiple rule skips the payment and caps the loan at a multiple of yearly income.

The calculator keeps the lowest of these loans, so the price never passes what any active rule allows, and it names the rule that set it. The loan is rounded down to the cent. The monthly payment shown is the one at the mortgage rate itself, which is lower than the test payment whenever a buffer or a minimum rate applies.

Canada: CMHC limits gross debt service to 39% and total debt service to 44% of gross income. Housing costs are principal, interest, property tax and heating, plus half of condo fees. The test rate is the greater of the contract rate plus 2 points and 5.25%, the rule CMHC and OSFI both state, and a fixed rate compounds twice a year.

United Kingdom: a loan of 4.5 times income or more counts as high loan to income. From 28 October 2026 such loans are held to 15% of new lending across the market, not per lender, so the multiple shows where a loan becomes high loan to income rather than a ceiling.

France: the HCSF decision of 29 September 2021 caps the debt ratio at 35% of net income before tax and the term at 25 years. A longer term is cut to 25 years.

Australia: APRA keeps the serviceability buffer at 3 percentage points above the loan rate. The ratio limits come from your lender, so the tool applies the buffer to the limits you enter.

A US option is not included because no CFPB, HUD or FHA page we could read states a single pair of ratios. The CFPB notes that limits differ by loan product and lender, so US buyers can enter their lender's limits under Custom.

Frequently asked questions

How much house can I afford on my salary?

It depends on the rule your lender applies. A ratio rule caps the monthly payment at a share of income, so the loan also depends on the rate and term. With 90,000 a year, a 28% limit and 6.5% over 30 years, the payment can be 2,100 a month, which supports a loan of about 332,000. An income multiple rule ignores the rate and caps the loan directly.

What are GDS and TDS in Canada?

Gross debt service (GDS) is the share of gross income that goes to housing: principal, interest, property tax and heating, plus half of any condo fees. Total debt service (TDS) adds every other debt payment. CMHC limits them to 39% and 44% for an insured mortgage, and the payment is tested at the greater of the contract rate plus 2 points and 5.25%.

Is 4.5 times income a hard limit in the UK?

No. UK regulators count a mortgage of 4.5 times income or more as high loan to income. From 28 October 2026 such loans may make up 15% of new mortgages across the whole market, and a single lender may go above that share. So many buyers borrow less than 4.5 times, and some lenders offer more.

What is the 35% rule for a mortgage in France?

The Haut Conseil de stabilité financière (HCSF) requires lenders to keep the borrower's debt ratio at or below 35% of net income before tax, counting every loan payment. The term may not pass 25 years, with up to 2 more years of deferral for a new build or major works. Banks may go beyond these limits for up to 20% of the loans they grant each quarter.

What is the serviceability buffer in Australia?

APRA expects banks to check that a borrower could still pay at a rate 3 percentage points above the loan rate. At 6.5% the test rate is 9.5%, so the same monthly limit supports a smaller loan. Each lender then applies its own living cost and income checks, which this calculator does not know. Enter the limits your lender quotes in the two boxes.

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