Sources we use
We rely on primary sources: the Federal Reserve (H.15 and FRED data), the Consumer Financial Protection Bureau and Regulation Z, the IRS, HUD and FHA mortgagee letters, the Department of Veterans Affairs, FHFA, Fannie Mae and Freddie Mac guides, the U.S. Census Bureau, the Energy Information Administration, NREL and Lawrence Berkeley National Laboratory. We do not use lender or contractor marketing, forums or social media as sources of fact.
How calculators are checked
Every calculator uses published, standard formulas. The code is covered by automated tests that check known answers (for example, a $200,000 loan at 6% for 30 years has a monthly principal-and-interest payment of $1,199.10, and interest-only on a $50,000 HELOC balance at 7.5% is $312.50 a month). We show the formula next to each tool so anyone can verify the result by hand.
What we will not publish
- Loan offers, rate quotes or recommendations to borrow from a particular lender.
- Paid placements, affiliate links or reviews written for a lender, installer or contractor.
- Claims we cannot support with a source.
Updates and corrections
Each page shows the date it was last updated. When the prime rate, loan limits, HUD, VA or IRS rules, or the survey data behind our cost figures change, we update the affected pages. If you find an error, tell us through the contact page and we will review it and correct it.