PayDownMath builds free calculators for homeowners deciding what to do with extra money — a bonus, an inheritance, the proceeds from a house that just sold.
Most mortgage calculators are published by lenders and servicers, and they tend to show the option that suits the publisher. Ask a recast calculator whether to recast, and it will show you a lower payment. It will not show you what happens if you send the same money and keep paying your current amount instead — which frequently saves more.
Every calculator here shows the alternatives alongside the option you searched for, including the option of doing nothing.
Everything runs on standard amortization math in your browser. Nothing you type is transmitted to a server or stored. The formulas are the same ones your servicer uses: a fixed payment applied monthly against a declining balance at your stated rate.
What the calculators cannot know is your servicer's specific rules — minimum amounts, fees, eligibility. Those vary, and the pages here say so wherever it matters.
[Replace this section with your name and a short line about your background before publishing. Google evaluates financial content partly on who stands behind it, and an anonymous site is at a measurable disadvantage.]
PayDownMath is free to use. The site is supported by display advertising and, where relevant, referral relationships with lenders. Advertising never determines what a calculator recommends — the math produces the same result regardless of who is advertising on the page.
This is not financial advice, and nothing here is a commitment from any lender. The calculators produce estimates from the numbers you enter. Before acting on any of it, confirm the specifics with your loan servicer.
If something here is wrong, tell us. See the contact page. Corrections are made promptly and the review date on the page is updated.