A Clear Path to Your Home Budget
A mortgage lender doesn't care how much you "feel" you can afford; they care about cold, hard mathematical risk. This calculator reverses the exact underwriting algorithm banks use to determine your maximum borrowing power.
By comparing your gross income against your existing consumer debt, and applying strict Debt-to-Income (DTI) limiters, we can calculate the absolute ceiling on your purchasing power. Knowing this number prevents you from wasting time touring houses you legally cannot buy.
The Golden Rule: 28/36 DTI
To use this calculator effectively, you must understand the two sliders at the bottom: the Front-End DTI and the Back-End DTI. The standard conventional lending standard is the "28/36 Rule".
- 28% Front-End Limit (Housing Ratio): A bank dictates that your total housing payment (PITI) should not exceed 28% of your gross monthly income.
- 36% Back-End Limit (Total Debt Ratio): A bank dictates that your housing payment plus all your other consumer debts (auto loans, student loans) should not exceed 36% of your gross income.
If you have zero debt, your Front-End ratio controls your destiny. If you have massive car loans, your Back-End ratio will throttle your purchasing power, severely limiting how much house you can afford.
What Does PITI Stand For?
When calculating affordability, you must calculate the total housing obligation, known as PITI.
- Principal: The portion of the payment that pays down the actual loan balance.
- Interest: The fee the bank charges you to borrow their money.
- Taxes: Annual property taxes assessed by your local county, divided by 12.
- Insurance: Mandatory homeowners insurance.
If you put down less than 20% in cash, a fifth letter is added: PMI (Private Mortgage Insurance). This is a punitive monthly fee that protects the lender if you default, driving your monthly costs up significantly.
Frequently Asked Questions
How can I quickly increase my home affordability?
You have three mathematical levers to pull:
- Destroy Consumer Debt: Paying off a $400/month car loan instantly frees up $400/month in your Back-End DTI, drastically increasing the size of the mortgage you qualify for.
- Save a Larger Down Payment: A massive down payment reduces the raw loan amount you need to borrow, which lowers the monthly payment constraint. Crossing the 20% threshold also eliminates the expensive PMI penalty.
- Increase Gross Income: Adding a side-hustle or applying with a high-earning co-borrower inflates the denominator of the DTI equation, granting you immediate purchasing power.
Should I choose a 15-year or 30-year loan term?
A 30-year loan stretches the math out, resulting in a much lower monthly payment. This artificially inflates your affordability, allowing you to buy a much more expensive home. However, you will pay staggering amounts of compound interest over three decades. A 15-year loan has aggressively higher monthly payments, suppressing your maximum purchase price, but it builds equity incredibly fast and saves hundreds of thousands of dollars in interest.