Why the second home affordability calculator matters
The first mortgage counts as debt on the second application, which is why second homes feel far less affordable than the first did at the same income. This page turns that decision into a handful of inputs you can defend in a budget review: volume, unit cost, rate of adoption, and time. The output is a planning baseline, not a promise — it tells you whether the idea deserves a vendor quote, a pilot, or a pass.
- • Biggest swing factor: the existing mortgage payment consuming the debt allowance
- • Second-order factor: the deposit available for the second property
- • Often ignored: the rate premium on non-primary residences
What actually changes the answer
the existing mortgage payment consuming the debt allowance moves this number first, then the deposit available for the second property. Run a conservative case and an upside case before you commit. If the maths only works in the upside case, treat it as a time-boxed test with a kill date rather than a line in next year's plan.
What to do with the result
If rental income will offset the cost, get the lender's rules on counting it before you rely on it.
Related guides
Long-form playbooks on the same topic, written by the RevenueLab editorial team.
FAQ
What does the second home affordability calculator work out?
It applies Max payment = min(36% × monthly income − debts, 28% × monthly income); Loan = payment × [(1 − (1 + i)^−n) ÷ i]; Price = loan + down payment to the values you enter for gross annual income, existing monthly debt payments, down payment / cash available, interest rate, loan term (years). The first mortgage counts as debt on the second application, which is why second homes feel far less affordable than the first did at the same income.
How accurate is this second home affordability calculator?
Treats the existing mortgage as monthly debt. It does not credit any rental income, which some lenders partially allow. Replace the defaults with your own invoice, usage export, payroll data, statement, or vendor quote before making a commitment — the maths is exact, so the answer is only as good as the inputs you feed it.
Which input should I stress-test first?
the existing mortgage payment consuming the debt allowance. Re-run with a pessimistic value for it; if the decision flips, that assumption is the thing you need real data on before signing anything. After that, check the deposit available for the second property and the rate premium on non-primary residences.
Which scenario should I start from?
Start with the preset closest to your situation — cautious budget, today's numbers, stronger position — then edit the sliders. Presets are realistic starting points, not benchmarks to match, and every change updates the result instantly.
What should I do after running the numbers?
If rental income will offset the cost, get the lender's rules on counting it before you rely on it. A useful planning benchmark to compare against: Second-home loans usually require 10% or more down and price slightly above primary rates.
Can I share or save this calculation?
Yes. Your inputs are written into the page URL, so copying the link shares the exact scenario you are looking at — the person who opens it sees the same numbers. You can also export the inputs and results to CSV or PDF from the result card and keep it with the rest of your workings.
How this calculator is built
Independently maintained
Written by Sam Doshi and the RevenueLab editorial team. We don't sell the data feeds this tool is built on.
Sourced from primary data
Benchmarks come from public AdSense / Stripe / IRS disclosures and reader-submitted data — never third-party "$X per view" claims. Full methodology.
Last editorial review
Reviewed on a rolling quarterly cycle. Dated reviews are published on the methodology record for each calculator.
Editorial standards
See our editorial policy and disclaimer. Results are estimates, not advice.