Payment, total interest, and the full month-by-month amortization schedule. Then the part most calculators skip: what happens when you change something partway through — start paying extra in year four, or switch to biweekly in year seven.
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A $400,000 loan at 6.5% over 30 years costs $2,528.27 a month, and $510,178 in interest over its life. Here's what adding a fixed amount to every payment does to that, from day one:
| Extra per month | Paid off in | Total interest | Interest saved |
|---|---|---|---|
| — | 30.0 years | $510,178 | — |
| $100 | 26.8 years | $446,261 | $63,917 |
| $200 | 24.4 years | $398,286 | $111,892 |
| $300 | 22.4 years | $360,597 | $149,581 |
The shape of that is worth noticing: the first $100 buys you $63,917, the second only $47,975, the third $37,689. Extra payments have diminishing returns, and they're worth most in the early years when almost all of your payment is interest. On this loan, the first month's payment puts $2,167 toward interest and $362 toward the balance.
Paying half your monthly payment every two weeks means 26 half-payments a year — 13 full payments instead of 12. On the same loan that's $392,682 in interest instead of $510,178, and the mortgage clears 5.8 years early.
That's a real saving, but the mechanism isn't magic and it isn't the fortnightly compounding: it's the one extra payment a year. Paying $1,264 every two weeks and paying an extra $211 a month land in almost the same place. Biweekly wins for people who are paid fortnightly and find the rhythm easier to keep up — which is a genuinely good reason, just not the one usually given.
Some lenders hold each half-payment until the second one arrives and then apply a normal monthly payment, which removes the entire benefit. Others charge to set up a biweekly plan. Making one extra manual payment a year, or adding a twelfth of your payment to each month, achieves the same thing with no arrangement to sign up for.
Most calculators assume you decide everything on day one: this rate, this term, this extra payment, for thirty years. Real loans don't work that way. You get a raise in year four. You switch to fortnightly pay in year seven. You come into some money and put $10,000 down in year twelve.
This calculator lets you change the payment amount or the payment frequency at a point in the schedule and recalculates from there, on the balance you'd actually have at that moment — rather than making you start a fresh calculation and guess what your balance will be. That's the specific gap it was built to fill.
It doesn't estimate property taxes, insurance or PMI, so the payment it shows is principal and interest — usually smaller than what actually leaves your account each month.
No. Calculations and the full schedule work without signing in. An account is only needed to save a scenario and come back to it.
It's the principal-and-interest payment. Most mortgage payments also include property taxes, homeowners insurance and sometimes PMI, collected into an escrow account — so your real monthly figure will be higher.
It depends on the gap between your rate and current rates, on the closing costs, and on how long you'll stay. Refinancing a rate that's meaningfully higher than today's usually beats extra payments; a small gap often doesn't cover the costs. Model the extra payments here to get one side of that comparison, and get a real quote for the other.
That's a question about your whole financial position, not just the loan, and we're not in a position to answer it for you — a mortgage at 6.5% is a guaranteed 6.5% return, which competes with paying down more expensive debt, employer retirement matching, and an emergency fund. What this tool does is tell you exactly what the mortgage side is worth, so the comparison is with a real number.
Yes. Any loan with a fixed rate and regular payments amortizes the same way — car loans, personal loans and student loans all work.
They're computed with standard amortization maths on the example loan described, rounded to whole dollars. They're an illustration of the shape of the thing — run your own numbers for anything you're deciding on.
Built by 3VNSYSTEMS. Practical software tools, built one at a time. Nothing here is financial advice.