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Mortgage Pre-Approval Calculator 2026: 43% DTI Real Numbers
Enter your income, debts, credit score, and down payment. See your maximum pre-approval amount and your comfortable affordability number side by side. No email required. No lender upsell. Just the math.
Rates last verified May 2026 | Conforming limit: $832,750 | FHA floor: $541,287
Your Financial Details
Monthly Debt Payments
Total: $850/mo
Leave blank to auto-fill from credit score. Override to test scenarios.
Quick Scenarios
Maximum Pre-Approval
$288,455
$259,609 loan + $28,846 down
DTI up to 43% | 6.125% rate
Comfortable Affordability
$180,284
$1,369/mo total payment
25% of $5,475 take-home
The gap: A lender may approve you for $288,455, but your comfortable number is $180,284. That is a $108,171 difference. The maximum stretches your budget to the limit; the comfortable number leaves room for savings, maintenance, and life.
Monthly Payment at Maximum Approval
Your DTI Ratios
Lender limit: 28%
Lender limit: 43%
How We Calculate This
Step 1: Your gross monthly income is $90,000 / 12 = $7,500
Step 2: Your existing monthly debts total $850
Step 3: Maximum housing payment = ($7,500 x 43%) - $850 = $2,375
Step 4: After property tax, insurance, and mortgage insurance, maximum P&I = $1,577
Step 5: At 6.125% over 30 years, that supports a $259,609 loan, or a $288,455 home with 10.0% down.
How Lenders Calculate Your Pre-Approval Amount
The single most important number in mortgage pre-approval is the debt-to-income ratio (DTI). Lenders calculate two versions: front-end DTI (housing costs only divided by gross monthly income, capped at 28%) and back-end DTI (all monthly debts including housing, divided by gross monthly income, capped at 43% for conventional or up to 50% for FHA).
The formula: (monthly debts + proposed housing payment) / gross monthly income = back-end DTI
Here is a worked example at $90,000/year income with $850/month in existing debts. Gross monthly income = $7,500. At 43% DTI limit, maximum total debt = $3,225/month. Subtract existing debts: $3,225 - $850 = $2,375 available for housing. Housing costs include principal and interest, property tax (~1.1% of home value annually), homeowner insurance (~$1,800/year), and PMI/MIP if under 20% down. After taxes, insurance, and PMI, roughly $1,800-$1,950 remains for P&I. At 6.37% on a 30-year term, that supports a loan of approximately $290,000-$310,000.
Compensating factors can push approval above standard DTI limits. With a credit score above 720, cash reserves of 6+ months of mortgage payments, or minimal payment increase from current rent, lenders using automated underwriting (Fannie Mae Desktop Underwriter) may approve back-end DTIs up to 50% on conventional loans. FHA manual underwriting allows similar flexibility with documented compensating factors.
Credit Score Impact on Mortgage Rates
April 2026 estimated rates based on a 30-year fixed mortgage. Monthly payments calculated on a $400,000 loan.
| Score Range | Est. Rate | Monthly P&I | 30-Year Interest |
|---|---|---|---|
| 760+ | 6.00% | $2,398 | $463,353 |
| 740-759 | 6.125% | $2,430 | $474,870 |
| 720-739 | 6.25% | $2,463 | $486,459 |
| 700-719 | 6.50% | $2,528 | $509,828 |
| 680-699 | 6.75% | $2,594 | $533,454 |
| 660-679 | 7.00% | $2,661 | $557,327 |
| 640-659 | 7.25% | $2,729 | $581,434 |
| 620-639 | 7.50% | $2,797 | $605,769 |
The difference between 760+ (6.00%) and 620-639 (7.50%) on $400,000 is $399/month or $142,416 over 30 years.
Down Payment Scenarios on a $400,000 Home
At 6.37% (30-year avg, April 2026). PMI estimates based on good credit (700+). Property tax 1.1%, insurance $1,800/year.
| Down Payment | Cash Needed | Loan Amount | Est. PMI | Total Monthly |
|---|---|---|---|---|
| 3% (Conv) | $12,000 | $388,000 | $162/mo | $2,736 |
| 3.5% (FHA) | $14,000 | $386,000 | $177/mo* | $2,747 |
| 5% | $20,000 | $380,000 | $158/mo | $2,669 |
| 10% | $40,000 | $360,000 | $150/mo | $2,508 |
| 20% | $80,000 | $320,000 | None | $2,167 |
*FHA MIP is 0.55% annually and does not drop off if you put less than 10% down. Conventional PMI drops off automatically at 78% LTV.
What to Do Before Applying for Pre-Approval
Pay down revolving balances
Paying off a $5,000 credit card with a $150/month minimum frees up $150/month in DTI capacity. That translates to roughly $24,000 more in mortgage approval. Target cards below 30% utilization, ideally below 10%.
Avoid new credit applications
New hard inquiries drop your score 5-10 points temporarily. New accounts reduce average account age. Do not open credit cards, finance furniture, or co-sign for anyone in the 3-6 months before your mortgage application.
Gather your documents early
Lenders need 2 years of W-2s or tax returns, 30 days of recent pay stubs, 2-3 months of bank statements, and government ID. Self-employed borrowers also need 2 years of business tax returns and a year-to-date P&L. Having these ready turns a 2-week process into days.
Save beyond the down payment
Closing costs run 2-5% of the loan amount ($6,000-$19,000 on a $380,000 loan), and lenders want to see 2-3 months of mortgage payments in reserves after closing. On a $2,400/month payment, that means $4,800-$7,200 in cash reserves beyond your down payment and closing costs.
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