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Mortgage Payment Shock Calculator
Lenders watch payment shock — the jump from your current rent or mortgage to the new PITI. This calculator quantifies it in dollars and as a share of income.
rent or current mortgage PITI
P&I + taxes + insurance + HOA
Monthly payment shock
+$1,250
57% more than today
New housing % of income
31.4%
target: under 28% on conventional
Old housing % of income
20.0%
Income share increase
+11.4% pts
Reading the number
Significant payment shock. Lenders may scrutinize affordability — and you should run a real post-purchase budget before signing.
Lenders look at payment shock when underwriting first-time buyers. A jump from $1,200 rent to $3,500 PITI is a flag even if DTI mathematically works, because it tests your ability to actually live within the new budget.
How to Use
- Enter your current housing payment — rent, or current mortgage PITI if you're buying up.
- Enter the new mortgage PITI (principal, interest, taxes, insurance, HOA).
- Enter gross monthly household income.
- Read the dollar and percentage shock plus the change in housing-to-income ratio.
Frequently Asked Questions
Why do lenders care about payment shock?
Big jumps from rent to PITI signal that the borrower hasn't been living at the new payment level. Even with a passing DTI ratio, payment shock above 100–150% raises underwriting questions, especially for first-time buyers.
What's an acceptable payment shock?
Under 50% is comfortable. 50–100% is a yellow flag — make sure you've already practiced saving the difference. Above 100% is a red flag and lenders may ask for compensating factors (large reserves, strong credit, low LTV).
How is this different from DTI?
DTI compares total debt obligations to income. Payment shock specifically compares your prior housing cost to the new one. You can have a healthy DTI with a huge payment shock, or vice versa.
Can I lower payment shock?
Yes — bigger down payment, longer term, paying down points to lower the rate, or buying less house. The fastest lever is usually price: a smaller mortgage produces less PITI and less shock.
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