Give your loan the second look: your real payoff date, what it truly costs in interest, and exactly how much an extra payment every month buys back — in dollars and in months.
How to use it: pick your loan type, enter the balance, rate, and term, then try an extra payment — The Math shows exactly what it buys back.
Every extra dollar goes straight to principal.
Principal & interest only — mortgage figures exclude taxes, insurance, and PMI. Assumes fixed rate and no prepayment penalty. Estimates for planning, not a loan offer.
A 30-year amortization is front-loaded: in the early years, most of each payment is interest, because the balance it's charged on is still nearly the whole loan. That's exactly why extra principal is most powerful early — a dollar sent in year two skips being borrowed for the next twenty-eight years. Run the accelerator above and watch the interest-saved number: it's largest when the loan is young, and it shrinks as you approach the finish line.
Aim the money carefully. If your payment includes escrow for taxes and insurance, "paying extra" through the normal channel can land in the escrow account, where it saves you nothing. The extra needs to reach principal — most servicers have a separate field or checkbox for it, and it's worth confirming on the next statement that the balance dropped by the full amount.
You may get pitched a "biweekly payment plan," sometimes with an enrollment fee. The entire trick is that 26 half-payments equal 13 full payments a year — one extra payment, dressed up. You can do the same thing free by adding one-twelfth of your payment to each month, which is exactly the kind of number the accelerator above is built to test. Prepayment penalties, meanwhile, are rare on recent conventional loans — but the note you signed is the final word, so check it once.
Two honest framings before you commit serious money. Paying down a mortgage is a guaranteed return equal to your rate — nothing to be ashamed of at today's rates, but it competes with keeping cash liquid and with higher-rate debts that should probably die first. And if what you actually want is a lower required paymentrather than a shorter loan, that's a different tool: our recast vs. refinance calculator compares the two ways to turn a lump sum into breathing room.
Estimates are principal and interest only. Check your loan contract for prepayment terms, and tell your lender extra payments go to principal — some default to advancing your due date instead.