Loan Affordability Calculator
Estimate how large a loan you can afford. Enter your gross monthly income, existing debts, interest rate and term, and get the maximum loan amount, monthly payment and purchase price your debt-to-income (DTI) limits allow.
Input
Income & Debts
Car payments, student loans, credit-card minimums, etc.
Loan Details
Optional cash you'll put down. Added to the loan to give a maximum purchase price.
Standard front-end / back-end DTI limits. Choose Custom to set your own.
Output
| Metric | Value |
|---|---|
| No data yet | |
Estimates for informational purposes only — not financial advice. Lenders weigh credit score, employment history and other factors, so the amount you qualify for may differ.
Guides
The Loan Affordability Calculator works out how much you can realistically borrow. Instead of starting from a loan amount and telling you the payment, it starts from your income and existing obligations and tells you the largest loan, monthly payment and purchase price your budget can support.
It uses the same debt-to-income (DTI) ceilings that lenders apply, then runs the standard amortization formula in reverse to convert an affordable payment into an affordable principal.
How to use it
- Enter your gross monthly income (before tax).
- Enter your existing monthly debts — car payments, student loans, credit-card minimums and any other recurring obligations.
- Set the annual interest rate and loan term in years.
- Optionally add a down payment to see the maximum purchase price (loan + cash down).
- Pick a DTI preset — Mortgage (28/36), Personal Loan (40/43), Auto Loan (35/40) — or choose Custom to set your own front-end and back-end limits.
Results update automatically as you type.
How affordability is calculated
Two DTI limits cap the monthly payment you can carry:
- Front-end DTI — the housing/loan payment as a share of gross income.
- Back-end DTI — all debt payments (the new loan plus existing debts) as a share of gross income.
maxHousingPayment = income × frontEndDTI%
maxTotalDebt = income × backEndDTI%
maxMonthlyPayment = min(maxHousingPayment, maxTotalDebt − existingDebts)
Whichever limit is lower becomes your ceiling — reported as the Limiting Factor. That monthly payment is then converted to a loan amount with the amortization formula solved for principal:
P = M × (1 − (1 + r)^−n) / r
where M is the maximum monthly payment, r is the monthly interest rate (annual rate ÷ 12), and n is the number of payments (years × 12). The tool also reports the total of all payments, the total interest paid over the life of the loan, and — when you enter a down payment — the maximum purchase price.
Why do existing debts reduce how much I can borrow?
Lenders look at your total debt load, not just the new loan. Every dollar of existing monthly payment eats into the back-end DTI ceiling, leaving less room for the new loan's payment. Paying down a car loan or credit card before applying can noticeably raise how much you qualify for.
What are good DTI limits?
The classic mortgage rule of thumb is 28% front-end / 36% back-end. Personal and auto lenders often allow higher ratios (up to ~43%). Use the presets as a starting point and switch to Custom to model a specific lender's guidelines.
Is this an official pre-approval?
No. This is an estimate for planning purposes. Lenders also weigh credit score, employment history, assets and the property itself, so the amount you're actually approved for may differ.
Privacy
The calculator runs entirely in your browser. Your income, debts and other figures are never uploaded or stored.