What an amortization schedule actually tells you
An amortization schedule is the month-by-month map of your loan: how much of each payment goes to interest, how much pays down principal, and what you still owe after every single payment. Early on, the split is brutal — on a 30-year loan at 6.5%, roughly 86 cents of every principal-and-interest dollar in month one is interest. It takes until around year 19 before more of your payment goes to principal than to interest. Seeing that flip point is the moment most people finally understand their mortgage — and start beating it.
The cheapest money you'll ever save: extra principal
Every extra dollar you send goes straight to principal — and every dollar of principal you remove stops earning interest against you for the rest of the loan. That's why small numbers do shocking things: $200 extra a month on a $300,000 loan at 6.5% saves roughly six figures of interest and pays the loan off years early. Use the What if tools above to test extra monthly payments, a one-time lump sum (a bonus, a tax refund, an inheritance) in any month you choose, or a recurring annual payment. Click any row of the schedule to drop an extra payment right there and watch the whole table recompute.
The truth about biweekly payments
Biweekly plans work — but not for the reason the brochures imply. Paying half your payment every two weeks means 26 half-payments a year: that's 13 full payments instead of 12. The magic isn't the frequency; it's the sneaky extra payment. You don't need to pay a servicer's "biweekly program" fee to get it — just add one-twelfth of your payment to each month, or make one extra payment a year. Toggle biweekly in the calculator above and see the payoff date move.
15-year vs 30-year: what the schedule reveals
A 15-year loan isn't just "the same loan, faster." Because the balance falls faster, dramatically less interest accrues — a 15-year at today's rates typically costs less than half the total interest of a 30-year on the same amount. The trade is a higher required payment and less flexibility. The nerd move many of our readers choose: take the 30-year for safety, then use the payoff-target tool above ("pay off in 15 years") to see the exact extra payment that gets you 15-year results with a 30-year escape hatch.
Does making extra payments change my monthly bill?
No — on a fixed-rate mortgage, extra principal payments shorten the loan and cut total interest, but your required monthly payment stays the same. The benefit shows up at the back of the schedule, not on next month's bill.
Why is my early payoff date an estimate?
The schedule assumes your rate, payment and extras stay as entered. Escrow changes (taxes, insurance) alter your total bill but not the principal-and-interest math shown here.