Home Affordability Calculator With Debt

Max Home Price by Income: How the Calculator Works

Most affordability widgets assume one ratio and hand back a single number. Underwriters check three things instead: your housing payment against gross income, your total debt payments against gross income, and whether your cash covers the loan's minimum down payment. They lend up to whichever limit you hit first. The calculator runs all three, reports the lowest as your max home price, and tells you which one it was.

Working backward from a budget is harder than it looks, because property tax, insurance and mortgage insurance all grow with the price. The engine searches for the highest price whose full payment still fits: principal and interest, 0.9% property tax, 0.6% insurance, PMI or FHA premium, and HOA. That search also handles the 20%-down kink. With $80,000 down, a $115,000 income and no other debt, the ceiling lands on exactly $400,000, because one dollar more would drop you below 20% down and add PMI to the whole loan. At a $120,000 income the budget clears that step and the ceiling moves to $407,775 with PMI included.

The 28/36 Rule, and Why 43% Is No Longer a Hard Wall

The front-end ratio compares your housing payment with gross monthly income; the back-end ratio adds every other monthly payment on your credit report. The classic 28/36 rule holds them to 28% and 36%. Because the two limits sit 8 points apart, debt payments under 8% of gross income never bind, and the housing ratio stops you first. Past that line, every dollar of debt payment comes straight out of the housing budget. Leave the switcher on Classic 28/36 and the tool behaves as a 28/36 rule calculator, with both ratios shown in the formula panel.

For years 43% DTI was the ceiling for a General Qualified Mortgage. The CFPB replaced that cap with a price-based test in its December 2020 General QM rule, with compliance mandatory from October 1, 2022, so today's practical limits come from investor guidelines. Fannie Mae's Selling Guide sets 36% for manually underwritten loans, 45% with qualifying credit scores and reserves, and 50% for loans run through Desktop Underwriter. The Conventional stretch and DU maximum settings reproduce those ceilings, and neither applies a separate housing ratio.

Back-End DTI: The Home Price Ceiling Your Debts Set

Debt costs less house than people expect, until it costs more. In the default example ($85,000 income, $25,000 down, 6.5%), the full $700/mo of car and student-loan payments trims the ceiling by only $16,186. The first 8% of income in debt payments hides inside the gap between the 28% and 36% limits. Past that line it is a different story: each extra $100/mo of payments removes $12,140 of price.

Lenders read the required monthly payment, not the balance, so the calculator asks for payments. A credit card with a $6,000 balance and a $180 minimum hurts your ratio exactly as much as a car loan with a $180 payment. That makes payment-to-balance the ratio to watch when choosing what to clear first: an auto loan with a few months left carries a big payment on a small balance, while paying down a large student loan on a long schedule frees up very little payment.

How Much House Can I Afford With Student Loans?

Student loans shrink the budget through the payment lenders count, and that figure depends on who backs the mortgage. Fannie Mae accepts a documented income-driven repayment amount, even $0; without one it uses 1% of the balance or the fully amortizing payment. Freddie Mac uses 0.5% of the outstanding balance when the reported payment is $0. FHA uses the reported payment when it is above $0, and 0.5% of the balance otherwise.

The gap between those rules is real money. A $40,000 balance on a $0 IDR plan counts as $0 with a Fannie Mae loan and $200/mo with Freddie Mac or FHA. Enter the figure your lender will use in the student-loan field, then flip between rule sets: if the back-end ceiling is binding, that $200 difference shows up directly in the price.

FHA Affordability vs Conventional: Which Lets You Afford More?

HUD Handbook 4000.1 puts FHA's manual-underwriting benchmarks at 31% for housing and 43% for total debt, with room to 37/47, 40/40 or 40/50 when compensating factors such as verified cash reserves apply. Loans approved through FHA's TOTAL Scorecard can go further still. Add the 3.5% minimum down payment at a 580+ credit score (10% between 500 and 579) and an FHA loan usually produces a higher ceiling than the 28/36 rule. Select FHA in the switcher and the rule-set chart lines it up against every conventional option.

The price is mortgage insurance that does not switch off at 20% down. HUD Mortgagee Letter 2023-05 set the annual premium at 0.55% of the loan for most 30-year loans with less than 5% down and 0.50% at 5% or more, on top of a 1.75% upfront premium that is usually financed. It lasts 11 years with at least 10% down and the life of the loan below that. Against the calculator's 0.8% default PMI, FHA's premium is often cheaper month to month for a low down payment; PMI can be cancelled and FHA MIP usually cannot, which is why refinancing into a conventional loan at 20% equity is a common exit.

PMI and the 20% Down Payment Line

Conventional loans add private mortgage insurance whenever the loan is more than 80% of the price. Urban Institute data puts the usual annual cost between 0.46% and 1.50% of the loan, driven mostly by credit score and down payment size. A home affordability calculator with PMI left out overstates your budget, so this one includes it and lets you replace the 0.8% default with the rate on your loan estimate.

PMI is also temporary. Under the Homeowners Protection Act you can ask your servicer to cancel it once the balance reaches 80% of the home's original value, and it ends automatically at 78%. Conventional minimums start at 3% down through Fannie Mae HomeReady and Freddie Mac Home Possible (97% LTV), which is the minimum the down-payment ceiling uses: $25,000 of cash covers 3% of a home up to $833,333, so for most conventional buyers savings are rarely the binding limit.

How Much House Can I Afford on My Salary?

Salary is only one input, but it anchors everything. The table uses 10% down, a 6.5% 30-year rate, 0.9% property tax, 0.6% insurance, 0.8% PMI and the classic 28/36 rule, first with no other debt and then with $700/mo of car and student-loan payments.

Read down the columns and a pattern appears. At $75,000 the $700 of payments is 11.2% of gross, well past the 8% line, and costs $26,530 of house. At $150,000 it is 5.6% of gross and costs nothing, because the housing ratio binds first. That is why a salary-only rule of thumb such as "three times income" breaks down: at 6.5%, $100,000 of salary supports 3.1 times income with no debt, and the multiple shrinks as rates or debts rise.

Dual-Income Home Affordability: Two Salaries, Two Debt Loads

Co-borrowers are qualified on combined gross income and combined debts, so switching on the co-borrower field changes both sides of every ratio at once. A second salary of $68,000 adds $5,667 of gross monthly income, which is $1,587/mo of extra room under a 28% housing ratio before any of that partner's own payments are subtracted.

The debts come along too. List both partners' car loans, student loans and card minimums in the debt panel; lenders will see all of them on the joint application. When one partner carries heavy payments on a modest income, run the numbers both ways with Scenario A vs B, since applying on one income occasionally beats a joint application.

Comfortable Mortgage Payment vs the Lender Maximum

Approval limits are built around default risk, not around daycare, retirement saving or a new roof. So beside the lender ceiling the calculator draws a comfort line at 25% of gross income for housing and 33% for all debt. It is our own conservative setting, not a lending rule, and it shows how much of the maximum is stretch.

The gap looks small per month and large in price. In the default example the comfort line allows a $1,638 payment against $1,850 at the maximum, just $212/mo apart, yet that is a $25,797 difference in the home you shop for. If you already know the payment that fits your budget, open the reverse solver's "Price from a payment" tab: enter the all-in monthly figure and it returns the price that payment buys at your rate, taxes and insurance.

Affordability by Interest Rate: What Each Point Costs

The rate cliff chart recomputes your ceiling across the current rate plus or minus 2 points in quarter-point steps, so you can see what a rate lock is worth before you shop. Going from 6.5% to 7.5% raises the 30-year payment per dollar borrowed by 10.6%, yet the default buyer's ceiling falls only 6.8%, because property tax, insurance and the down payment do not move with the rate.

A bigger down payment cushions rate risk for the same reason. The 20%-down saver preset loses 5.8% of its ceiling for the same one-point move, and a buyer at the 3% minimum loses more. The report card's Rate Resilience grade tracks exactly this: the share of your max price that a one-point rise would erase.

How Much Debt to Pay Off Before Buying a House

Paying off debt only helps when the back-end ratio is the binding limit. The reverse solver checks that for you: give it a target price and it solves three separate levers, the monthly debt payments to eliminate, the extra gross income needed, and the extra down payment. If paying off every debt still leaves you short, it says so instead of pointing you at a lever that cannot work.

In the default example that happens at $285,000. Even with zero debt the housing ratio caps the price at $261,980, so the debt lever is marked as not enough, while $10,765 more income a year or an extra $32,000 down would reach it. The solver also converts a monthly payment into a rough balance using a 5-year loan at 7%, a quick way to see whether a car loan is the cheapest path to the house you want.

A First-Time Home Buyer Affordability Checklist

First purchases fail on the number nobody checked. Before a pre-approval call, run these five checks in the calculator:

1. Enter the debt payments a lender will see on your credit report, including card minimums, not just the loans you think of as debt.
2. Compare Classic 28/36 with FHA 31/43. If FHA wins, weigh its lifetime MIP against the extra price.
3. Check whether the down-payment ceiling is binding. Conventional loans can start at 3% down and FHA at 3.5%, but closing costs come on top.
4. Look at the comfort line, not just the maximum, and decide which one you will shop at.
5. Move the rate one point up in the what-if sliders and make sure you could still buy the home you want.

Frequently Asked Questions

Related Finance Tools