Mortgage Affordability Calculator
Estimate how much you could borrow, based on income, existing debts and a debt-to-income limit.
Your figures
Result
How to use this tool
- Enter your figures in the fields on the left.
- Results update instantly as you type — there is no button to press.
- Change any input to see how sensitive the answer is to it.
Lenders assess debt-to-income ratio. 36% is a common conventional threshold, though some programmes allow up to 43% or higher. This is an estimate, not a pre-approval.
How it works
The calculation runs in your browser as you type — there is no submit button and nothing is sent anywhere. Change any figure and the results update immediately, which makes it easy to see how sensitive the answer is to each input.
Every formula used here is standard and documented in the questions below. Where a result depends on an assumption, the assumption is stated rather than buried.
Frequently asked questions
What debt-to-income ratio do lenders use?
36% is a common conventional guideline for total debt including the new mortgage. Some government-backed programmes permit 43% or more.
Why is my lender’s figure different?
Lenders include property tax, insurance and HOA in the ratio, and apply their own credit and reserve rules. Treat this as a starting point.
Should I borrow the maximum?
Rarely. The maximum leaves nothing for maintenance, rate rises, or life changes. Many people target a payment well below their ceiling.
Is this calculator free?
Yes, with no account, no limits and no data collection. It runs entirely in your browser.
Should I rely on this for a financial or medical decision?
No. It is a planning estimate built on standard formulas and stated assumptions. For decisions that matter, speak to a qualified professional who can account for your full circumstances.
Is this calculator accurate?
The arithmetic is exact — it uses the standard formula, shown in the questions above. What limits accuracy is the assumptions: the figures you enter, and factors the formula does not model such as fees, taxes and rule changes. Treat the result as a well-founded estimate rather than a quotation.
Do I need to sign up or download anything?
No. It runs in your browser, updates as you type, and stores nothing. There is no account, no download, and no limit on how many times you use it.
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Your files stay on your device. This tool runs entirely in your browser. No file is uploaded, transmitted, or stored. You can verify this by opening your browser's Network tab while using the tool.
Disclaimer. This calculator provides estimates based on standard formulas and the assumptions stated above. It is not financial, medical, tax or legal advice. For decisions that matter, consult a qualified professional. See our full disclaimer.