Monthly income is your gross annual divided by 12 — that's what lenders use. The DTI rule caps your housing-related spending at a percentage of that monthly income. 28% front-end means PITI alone; 36% back-end means PITI + car loans + student loans + minimum credit-card payments. 43% is the legal ceiling for a "qualified mortgage" in the US after Dodd-Frank. PITI stands for principal, interest, taxes, insurance. Your principal & interest payment is solved from the standard amortization formula (P&I = L × r(1+r) n / ((1+r) n −1) where L is loan amount, r is monthly rate, n is months). T&I is approximated as a percentage of home value per year — typically 1.0–2.5% in the US depending on state, much lower in most of Europe. We solve the home price algebraically : maxPITI = (H − down) × piFactor + H × tiFactor, then re-arrange for H. Loan principal is then maxHome − down payment.

PMI is not included. If your down payment is under 20%, expect 0.3–1.5% of the loan amount per year in private mortgage insurance. This calculator does not account for it — assume your real max is 5–10% lower than the figure shown when LTV > 80%. HOA / condo fees aren't modelled. A condo with $400/month HOA effectively reduces the housing budget by $400 — subtract it from your income inputs by adding $400 to monthly debts, or just mentally adjust. Tax/insurance varies wildly by location. 1.5% is a US average. Texas and New Jersey are 2.5%+; California is around 1.1%; most of Europe is well under 1%. Look up your area before relying on this number. DTI is a ceiling, not a recommendation. Living right at 36% DTI leaves no buffer for car repairs, kids, or a roof. Many financial planners suggest 25–30% housing including taxes as a comfortable target. Lenders also look at credit score, employment history, and reserves. A DTI calculator tells you the maximum a lender would underwrite assuming everything else is fine — it doesn't guarantee approval. Variable-rate mortgages need a stress test. If your rate could rise 2 percentage points, recompute at the higher rate and make sure that's still livable.

loan-calculator — once you pick a target price, switch over to see the full month-by-month amortization, total interest, and "what if I pay extra" scenarios. percentage-calculator — for quick sanity checks on down-payment percentages, fee splits, etc.

Mortgage Affordability Calculator

How much house can I afford? Income + monthly debts + down payment + interest rate → max purchase price under the 28/36 DTI rule.

Gross annual income

Monthly recurring debts (car, cards, student loans)

Down payment

Interest rate (annual %)

Term (years)

Property tax + insurance (% of home price / year)

DTI rule

Currency symbol

Result

What is this for?

Before you fall in love with a listing, it's worth knowing the ceiling. This calculator answers "how much house can my income support?" by inverting the standard mortgage math: instead of asking what a $400,000 home costs per month, it asks what home price corresponds to the maximum monthly payment your debt-to-income ratio allows. The result is the price at which a lender stops underwriting — useful for setting a budget, shortlisting neighbourhoods, or sanity-checking what your agent says you "qualify for".

How it works

Monthly income is your gross annual divided by 12 — that's what lenders use.
The DTI rule caps your housing-related spending at a percentage of that monthly income. 28% front-end means PITI alone; 36% back-end means PITI + car loans + student loans + minimum credit-card payments. 43% is the legal ceiling for a "qualified mortgage" in the US after Dodd-Frank.
PITI stands for principal, interest, taxes, insurance. Your principal & interest payment is solved from the standard amortization formula (P&I = L × r(1+r)ⁿ / ((1+r)ⁿ−1) where L is loan amount, r is monthly rate, n is months). T&I is approximated as a percentage of home value per year — typically 1.0–2.5% in the US depending on state, much lower in most of Europe.
We solve the home price algebraically: maxPITI = (H − down) × piFactor + H × tiFactor, then re-arrange for H. Loan principal is then maxHome − down payment.

Common gotchas

PMI is not included. If your down payment is under 20%, expect 0.3–1.5% of the loan amount per year in private mortgage insurance. This calculator does not account for it — assume your real max is 5–10% lower than the figure shown when LTV > 80%.
HOA / condo fees aren't modelled. A condo with $400/month HOA effectively reduces the housing budget by $400 — subtract it from your income inputs by adding $400 to monthly debts, or just mentally adjust.
Tax/insurance varies wildly by location. 1.5% is a US average. Texas and New Jersey are 2.5%+; California is around 1.1%; most of Europe is well under 1%. Look up your area before relying on this number.
DTI is a ceiling, not a recommendation. Living right at 36% DTI leaves no buffer for car repairs, kids, or a roof. Many financial planners suggest 25–30% housing including taxes as a comfortable target.
Lenders also look at credit score, employment history, and reserves. A DTI calculator tells you the maximum a lender would underwrite assuming everything else is fine — it doesn't guarantee approval.
Variable-rate mortgages need a stress test. If your rate could rise 2 percentage points, recompute at the higher rate and make sure that's still livable.

Pairs with

loan-calculator — once you pick a target price, switch over to see the full month-by-month amortization, total interest, and "what if I pay extra" scenarios.
percentage-calculator — for quick sanity checks on down-payment percentages, fee splits, etc.