3VNSYSTEMS

Extra payment calculator

Put a number against the question. How much does an extra $200 a month actually take off the loan — and how much of that is still on the table if you don't start until year ten?

Run your numbers

Free, and no account needed to calculate.

When you start matters more than how much

Every guide tells you extra payments save money. Almost none of them tell you that the same $200 a month is worth wildly different amounts depending on when you begin — because early payments are almost all interest, and a dollar of principal paid in year one avoids twenty-nine years of interest on that dollar.

$400,000 at 6.5% over 30 years. Adding $200 to every payment, starting at different points.
Extra $200 startingPaid off inInterest saved
Year 124.4 years$111,892
Year 526.0 years$71,472
Year 1027.3 years$41,859
Year 1528.2 years$21,475
Year 2029.1 years$8,690

Waiting ten years costs you $70,033 of the available saving — and you'd still be paying the same $200 every month for most of the loan. That's the argument for starting small now rather than waiting until you can afford to start big.

It cuts the other way too. If you're twenty years into a mortgage, extra payments are close to the least effective thing you can do with the money, because there's barely any interest left to avoid. At that point the comparison isn't extra payments versus nothing — it's extra payments versus almost anything else.

How much extra is worth it

On the same loan, starting from day one, each additional $100 a month buys less than the one before:

Still a good return at every step, just a shrinking one. There's no threshold below which extra payments stop mattering — $50 a month from year one beats $200 a month from year fifteen.

Make sure it goes to principal

Extra money sent without instruction is often applied to your next scheduled payment rather than the balance — which means it sits there and saves you nothing. Most lenders have a "principal only" option; some need it in writing. Check the first statement after you start, and confirm the balance dropped by what you sent.

Before you commit the money

Questions

Does paying extra reduce my monthly payment?

No. It shortens the loan instead — the payment stays the same and you make fewer of them. Reducing the payment itself needs a recast, which some lenders offer for a fee after a large lump sum.

Is a lump sum or a monthly extra better?

For the same total, earlier beats later, so a lump sum now generally beats the same amount spread over a year. The bigger factor is consistency: a monthly amount you actually keep up with beats a lump sum you keep meaning to make.

What if I can only pay extra some months?

It still works. There's no schedule to commit to and no penalty for skipping — every extra dollar that reaches the principal shortens the loan by whatever it shortens it by.

I'm already ten years in. Is it too late?

Not too late, just worth less — $41,859 instead of $111,892 in the example above. Enough to be worth doing, not enough to be an obvious priority over other uses of the money.

Are these numbers accurate?

They're computed with standard amortization maths on the example loan described, rounded to whole dollars, principal and interest only. Run your own loan through the calculator for figures you'd act on.

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Built by 3VNSYSTEMS. Practical software tools, built one at a time. Nothing here is financial advice.