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Mortgage affordability calculator
Estimate mortgage buying power from a monthly payment, interest rate, loan term, deposit and upfront-cost scenario.
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No regional currency, unit or language profile is applied. This choice does not convert values or change formulas, results, routes or legal guidance.
Estimated buying power
$275,461.35Estimated loan: $225,461.35 · Upfront cash: $62,000.00- Loan supported
- $225,461.35
- Deposit included
- $50,000.00
- Monthly payment
- $1,500.00
- Rate and term
- 7% · 30 years
Compare affordability scenarios
These examples change one assumption at a time so you can see what drives the estimate.
| Scenario | Assumption | Estimated buying power | Difference |
|---|---|---|---|
| Current assumptions | 7% rate · $1,500.00/month | $275,461.35 | — |
| Rate 1 point lower | 6% rate · same payment | $300,187.42 | +$24,726.07 |
| Monthly budget 10% higher | $1,650.00/month · same rate | $298,007.49 | +$22,546.14 |
| Deposit 10% higher | $55,000.00 deposit · same loan | $280,461.35 | +$5,000.00 |
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Verification and calculation details
- Purpose
- Mortgage affordability calculator
- Variables and units
- Use the labelled fields and units shown in the calculator. Results use those units unless a conversion is stated.
- Formula and method
- The exact formula and worked example are shown below. Deterministic formula executed locally in the browser.
- Assumptions
- Only entered values and stated assumptions are included. Local fees, rules and professional requirements are excluded unless explicitly shown.
- Engine version
- 1.0.0
- Production verification baseline
- Release 63 · source
998803f - Verification run
release-v63-2026-09-20- Last verified
- — Automated release checks passing
Read the Calculation Standard · Report a calculation or source issue
How this calculator works
Supported loan principal is calculated by reversing the standard amortizing-loan formula. Estimated buying power = supported loan principal + deposit. Estimated upfront cash = deposit + entered upfront costs.
Variables and inputs
- Maximum monthly payment
- Required numeric input. finite numeric value; calculator-specific validation applies.
- Annual interest rate
- Optional numeric input. finite numeric value; calculator-specific validation applies.
- Loan term
- Optional numeric input. finite numeric value; calculator-specific validation applies.
- Deposit or down payment
- Optional numeric input. finite numeric value; calculator-specific validation applies.
- Estimated upfront costs
- Optional numeric input. finite numeric value; calculator-specific validation applies.
- Display currency
- Optional numeric input. fixed offline currency-code allowlist; presentation only; no exchange-rate conversion.
How to interpret the result
The calculator returns supported loan principal, estimated property buying power, deposit contribution, estimated upfront cash requirement, principal-and-interest payment scenario. Read each output against the assumptions you entered, compare alternatives one variable at a time, and use the result as an estimate rather than a promise.
Common mistakes to avoid
- Mixing units or entering a rate as a decimal when the field requests a percentage.
- Rounding intermediate values instead of the final displayed result.
- Leaving out a cost, timing rule or local requirement listed in the assumptions below.
Practical uses
Use the mortgage affordability calculator to check a real scenario, compare a changed assumption and explain the arithmetic before relying on a quote, specification or decision.
Worked example
A principal-and-interest budget of $1,500 per month at 7% over 30 years supports an estimated loan principal of about $225,461.35. With a $50,000 deposit, the buying-power scenario is about $275,461.35 before taxes, insurance and fees.
Assumptions and limitations
- the entered monthly budget covers principal and interest only at a fixed annual rate
- deposit and upfront costs are cash inputs and do not include taxes, insurance or lender affordability rules
- results are estimates; confirm rates, prices, units and professional requirements that apply
Important notes
Results are estimates based on the values entered. Confirm rates, prices, units and professional requirements that apply in your location. Review the Answer Atlas Calculation Standard and corrections policy for formula, privacy and correction rules.
Frequently asked questions
Is this the same as a lender approval?
No. Lenders may consider income, expenses, credit history, deposits, insurance, property taxes, insurance, legal costs and local affordability rules.
Why include a deposit or down payment?
A deposit can increase the estimated property price you may compare, but it does not change the principal-and-interest loan supported by the monthly payment.
Does this include taxes, insurance or closing costs?
No. Enter an upfront-cost estimate for planning, then confirm all local fees, transfer costs, insurance and professional requirements before making a decision.
Why does a lower interest rate increase affordability?
When less of each payment is used for interest, the same monthly budget can support a larger principal.