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Mortgage Affordability Calculator

Work out the loan a given income and deposit supports, using the debt-to-income limits lenders actually apply.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Loan supported

391299.86 loan

Check your inputs

Arithmetic on the figures you enter. Not a lending decision, not an offer, and not regulated financial advice — speak to a qualified adviser before acting on it.

Monthly income
6250
Total debt allowance at the stated DTI
2687.5
Available for the mortgage
2287.5
Other debts consuming allowance
400

For the dimensions entered, expect a loan supported of 391300. Note that gross annual income and other monthly debt payments sit at the edge of the range this calculator was checked against, so treat the output as indicative rather than settled. Moderate confidence — sound arithmetic, but allow for the variation any real site introduces. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Add the equipment this sizes

This result is a specification — 391,299.858 loan — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • 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

Your workspace

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.

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.