See your loan the way an underwriter does.
See how the mortgage math works, with the rulebook open
Plain-language explanations of how lenders calculate a house payment, debt-to-income, loan-to-value, mortgage insurance, and closing costs for Conventional, FHA, VA, and USDA loans. Every rule links to the official guideline it comes from, with the date we last checked it.
Try “escrow”, “discount points”, “Closing Disclosure”, or “child support”.
Browse by topic
Getting started
What goes into a monthly payment, the steps from application to funding, and the documents lenders ask for.
Loan programs and qualifying
Conventional, FHA, VA, and USDA rules, DTI and LTV, credit-score tiers, and minimum down payments.
Mortgage insurance
PMI, FHA premiums, the VA funding fee, USDA fees, and when each one ends.
Closing
Closing costs, the Loan Estimate and Closing Disclosure, title, liens, and inspections.
Taxes and escrow
Why escrow payments jump, tax value vs. sale price vs. appraisal, and homestead exemptions.
Rates and ARMs
Adjustable-rate caps, discount points, and temporary buydowns.
Special situations
Child support and alimony in a mortgage file, and buying a newly built home.
Reference
Mortgage glossary, A to Z
Plain definitions of 75 terms, each linked to the page with the full rules. Jump to a common one:
Calculators
Every calculator runs in your browser, starts blank, and shows the rule it uses with its source.
Payment calculator (PITI)
Principal and interest, taxes, insurance, HOA, and the program’s mortgage insurance or upfront fee.
DTI calculator
Front-end and back-end debt-to-income ratios, with what counts as a monthly debt.
LTV and CLTV calculator
Loan-to-value and combined loan-to-value, using the lower of price or appraised value.
Mortgage insurance comparison
PMI, FHA MIP, the VA funding fee, and USDA fees side by side on the same numbers.
Closing cost calculator
Add up costs the way the Loan Estimate groups them and estimate cash to close.
Escrow jump calculator
The new payment after a tax or insurance increase and an escrow shortage.
ARM worst-case calculator
The highest rate and payment an ARM’s caps allow.
Points break-even calculator
How many months of lower payments it takes to earn back the cost of points.
Amortization calculator
How each payment splits between principal and interest, month by month or year by year, with a chart.
Extra payments calculator
How extra monthly, yearly, or one-time principal payments change the payoff date and total interest.
How we source things
Each rule on this site cites the handbook, guide section, regulation, or agency page it comes from. See Sources & editorial policy for the full list.