Answer: Enter the amount, rate, and term and the Loan Payoff Calculator returns your exact periodic payment with a full amortization breakdown of principal versus interest.
See how extra payments save you thousands in interest and years off your loan
Making extra payments on your loan is one of the most effective ways to save money. Even small additional amounts applied directly to your principal can dramatically reduce the total interest you pay over the life of the loan and shorten your repayment term by years.
On a $250,000 30-year mortgage at 6.5%, the standard payment is $1,580 a month and the loan accrues $318,861 in interest over three decades. Adding just $200 a month saves nearly $98,000 of that interest and pays the loan off almost 8 years early. The earlier you start, the bigger the effect, because interest compounds against whatever balance is still standing.
It's worth seeing where a single payment actually goes. In month one of that loan, $1,354 of the $1,580 payment is interest — 86% of it. By the final year, interest is down to roughly 3% of each payment. Extra payments work precisely because they attack the balance while it's still interest-heavy, collapsing the schedule from the front.
| Extra per month | New payoff time | Years cut | Interest saved |
|---|---|---|---|
| $0 (baseline) | 30.0 years | — | — |
| $100 | 25.3 years | 4.7 | $58,860 |
| $200 | 22.1 years | 7.9 | $97,618 |
| $300 | 19.7 years | 10.3 | $125,514 |
| $500 | 16.2 years | 13.8 | $163,516 |
Computed on the reference loan: $250,000 at 6.5% for 30 years, payment $1,580. The pattern to notice is the diminishing-but-still-strong curve — the first $100 of extra payment does the heaviest lifting, and every increment after still earns a guaranteed return equal to your rate.
The famous biweekly-payment plan is just a schedule trick: 26 half-payments equal 13 full payments, so you sneak in one extra payment a year. On the reference loan that's worth about $131.68 a month, which pays the loan off 5.8 years early and saves roughly $72,700 — between the $100 and $200 monthly rows in the table above, exactly where it should land. You can replicate the same effect yourself by adding 1/12th of your payment every month and skipping the enrollment fees biweekly programs charge.
Lump sums work too, and timing matters more than size. A single $5,000 principal payment in month one saves about $27,900 over the life of the reference loan and clears the balance 20 months early. The same $5,000 sent in year five saves less, because five years of balance never got the relief.
This calculator uses standard amortization math to compute your monthly payment, then simulates what happens when you add extra money each month. It shows you exactly how much interest you save, how many years you cut off the loan, and provides a full month-by-month amortization schedule so you can see the impact over time.
The other two tabs cover the neighboring problems. The mortgage tab prices a full monthly payment — principal and interest plus property tax and insurance — for a new purchase, the same math as our mortgage calculator. The compound interest tab runs the same engine in reverse: money growing instead of debt shrinking, so you can compare what an extra $200 a month earns invested versus what it saves prepaid. For the month-by-month table view of any of these, the amortization schedule tool lays out the full timeline, and the compound interest calculator covers the investing side in more depth.
Prepaying a 6.5% loan is a guaranteed 6.5% return, which is excellent — but a few things beat it. Kill higher-rate debt first: a 24% credit card balance costs more than any mortgage saves, and the loan calculator makes the ordering obvious. Keep an emergency fund intact; a paid-off loan you re-borrow against in a crisis at a worse rate is a loss. If your loan carries PMI, extra principal can get you to the 20% equity threshold faster, which stacks a second saving on top. And if your employer matches 401(k) contributions, that match is a 100% return no prepayment can touch. The deeper playbook for mortgage-specific strategy is in our guide to mortgage payoff with extra payments, and the underlying mechanics are explained in how to calculate a loan payoff.
Not always. Some servicers apply any amount above the minimum to your next scheduled payment unless you designate it as a principal-only payment. After making an extra payment, check the transaction breakdown on your statement: if it shows the extra as an advance on next month rather than a principal reduction, call the servicer and have it re-applied.
Yes, and the effect is larger than most people expect. On a $250,000 30-year loan at 6.5%, one extra payment a year — the biweekly-payment trick — pays the loan off about 5.8 years early and saves roughly $72,700 in interest. The savings come from never letting that balance linger, not from any magic in the biweekly timing itself.
The earlier the money hits the balance, the more it saves, because interest accrues on whatever principal is outstanding. A $5,000 lump sum in month one of a $250,000 loan at 6.5% saves about $27,900 over the life of the loan; the same check sent in year five saves noticeably less, since five years of balance never got the benefit. If you have the cash and an emergency fund besides, sooner beats bigger.
Paying off a 6.5% loan is a guaranteed 6.5% return — no investment offers that guaranteed. Against riskier expected returns, the honest answer is that prepaying wins on certainty and cash flow, while investing wins on expected value if returns reliably exceed your rate. Many people split the difference: establish an emergency fund, capture any employer 401(k) match first, then direct the surplus at the loan.