Payoff tool · West Capital Lending, Inc.
Mortgage Calculator With Extra Payments
See exactly how extra principal payments shorten your loan and cut your interest — month by month, not guesswork.
Extra payments applied to principal shrink the balance your interest is charged on, so the loan ends sooner and costs less overall. This calculator runs a true month-by-month amortization, so the payoff date and interest saved are precise for the numbers you enter — not a rough rule of thumb. Adam DeCraene (NMLS# 2811542), Mortgage Loan Originator with West Capital Lending, Inc., built it for homeowners weighing extra payments against refinancing or a HELOC.
Your loan & extra payments
The pre-filled figures are examples only — replace them with your own. They are not current rates, quotes, or offers.
Enter your numbers to see how much sooner you could pay off your loan.
Without extra payments
Your loan on its standard schedule.
$0/mo Standard monthly principal & interest- Payoff time
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- Total months to payoff
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- Total interest paid
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With extra payments
Same loan, with the extra principal you entered.
— New payoff time- Total months to payoff
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- Total interest paid
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- Monthly payment (standard + extra monthly)
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Estimates only. This calculator is an educational estimate based on a true month-by-month amortization — not a rate quote, an offer of credit, a commitment to lend, or financial advice. It assumes payments are made on time and that extra amounts are applied to principal. It shows principal and interest only and excludes taxes, insurance, HOA dues, and mortgage insurance (PMI/MIP). The final payment is adjusted so the balance never goes below zero. When you make extra payments on a real loan, designate them as principal with your loan servicer so they reduce your balance instead of prepaying interest. For exact numbers on your situation, talk to Adam DeCraene, Mortgage Loan Originator, NMLS# 2811542 — call or text 949-393-6360.
The mechanics
How Extra Payments Work
A mortgage is amortized: every month, interest is charged on the balance you still owe, and whatever is left of your payment reduces that balance. Early in the loan the balance is at its largest, so most of each payment is interest. Anything extra you pay toward principal removes that amount from the balance — and from every future month's interest calculation.
That is why an extra dollar paid in year one saves more than the same dollar paid in year twenty: the early dollar stops accruing interest for the entire remaining life of the loan. It is also why extra payments compound quietly — a lower balance this month means less interest next month, which means more of next month's payment reaches principal, and so on.
One thing extra payments do not do: change your required monthly payment. Your standard payment stays exactly the same — the loan simply ends early, sometimes years early, because the balance reaches zero sooner. If your income changes, you can stop the extra payments at any time and fall back to the standard schedule.
Two practical details matter. First, tell your servicer to apply extra amounts to principal — many servicers let you set that instruction permanently, so you don't have to specify it every month. Second, most modern mortgages have no prepayment penalty, but that isn't universal — check your own loan documents to be sure before you start. These are general points about how amortization works, not advice about your specific loan.
Worked example
One Loan, Run Step by Step
These are the calculator's pre-filled example figures, worked by hand so you can see exactly where each number comes from. The 6.5% rate is an example assumption entered for the estimate — it is not a rate quote.
Start with the loan
A $420,000 loan at the example rate of 6.5% over 30 years has a standard principal & interest payment of $2,655/month.
See the baseline cost
Paid on the standard schedule — 360 payments, no extras — that loan costs $535,687 in total interest before it is paid off in 30 years.
Add $200 a month to principal
Paying $200 extra toward principal every month shrinks the balance faster each month, so every following month's interest charge is smaller too.
Watch the payoff move up
The loan is gone in 24 years, 8 months — 5 years, 4 months sooner — and total interest falls to $422,464.
Count the savings
$535,687 − $422,464 = $113,223 in interest saved, from $200 a month. Try your own loan in the calculator above — the results update as you type.
| Extra principal per month | Mortgage-free in | Total interest | Interest saved |
|---|---|---|---|
| $0 (standard schedule) | 30 yrs 0 mos | $535,687 | — |
| +$100/mo | 27 yrs 0 mos | $471,329 | $64,358 |
| +$200/mo (calculator default) | 24 yrs 8 mos | $422,464 | $113,223 |
| +$300/mo | 22 yrs 9 mos | $383,762 | $151,925 |
| +$500/mo | 19 yrs 9 mos | $325,790 | $209,897 |
Estimates computed by true month-by-month amortization at the example rate of 6.5% — a modeling assumption, not a rate quote. Your loan's figures will differ.
Strategies
Four Ways to Pay Extra
There is no single right schedule — each of these gets extra money to principal in a pattern that fits a different budget and pay cycle:
A fixed extra amount every month
The simplest approach: add a set amount — $100, $200, $300 — to every payment, designated as principal. It is predictable, easy to automate, and because it starts immediately, each dollar works for the longest possible time.
Biweekly half-payments
Pay half your monthly payment every two weeks instead of the full payment monthly. That is 26 half-payments a year, which equals 13 full payments — one extra payment a year, spread so smoothly most people barely notice it. Check whether your servicer applies the partial payments promptly or holds them until a full payment accumulates.
An annual lump sum
Send a bonus, a tax refund, or another once-a-year windfall straight to principal. The calculator models this too — enter it as an extra yearly payment, or as a one-time lump sum in a specific month, and compare it against the monthly route.
Round the payment up
Round your total monthly outlay up to the nearest $50 or $100 and send the difference to principal. On a $2,655 payment, paying $2,700 or $2,750 is painless for most budgets — and as the worked example shows, even $100 a month moves the payoff date by years.
Keep the order right: an emergency fund comes before extra principal — home equity is not money you can reach in a hurry. And extra payments are only one lever. Depending on your rate, your equity, and your goals, refinancing or a HELOC may do more for you than prepaying — Adam can run that comparison with the Refinance vs. HELOC calculator on the main site and walk through all three side by side.
Common questions
Extra Payment FAQs
How much do extra payments actually save?
It depends on your loan amount, your rate, and how early and consistently you pay extra — but the savings are often larger than people expect. On the worked example on this page — a $420,000 loan at an example rate of 6.5% over 30 years — adding $200 a month to principal pays the loan off 5 years 4 months early and saves about $113,223 in interest, while $500 a month saves about $209,897. Your own figures will differ; enter your loan in the calculator to see them. All figures are estimates computed from the numbers entered, not promises of savings.
Is it better to pay extra every month or one lump sum a year?
Paying extra every month saves slightly more than paying the same total as one lump sum at the end of the year, because interest is charged monthly on the remaining balance — every extra dollar stops accruing interest starting the month it is paid. The difference is modest, though. A steady monthly amount, an annual bonus or tax refund applied to principal, or a mix of both all work; the best plan is the one you will actually keep.
Do extra payments go toward principal automatically?
Not always. Many servicers apply extra money to principal when you designate it that way, but some apply an overpayment to future payments — effectively prepaying interest — unless you specify otherwise. Mark extra amounts "principal only" when you pay, and ask your servicer whether you can set a standing instruction so every extra dollar goes to principal automatically.
Do mortgages have prepayment penalties?
Most modern mortgages do not have prepayment penalties, but some loans do — it depends on the loan program and the terms you signed. Your loan documents, including the note and any riders, say for sure. Check them before you start paying extra; if you are unsure what to look for, Adam can point you to the language to check.
Should I pay extra on my mortgage or invest the money instead?
There is no universal answer, and this is an educational comparison, not personalized financial advice. Extra principal payments produce a guaranteed saving equal to your loan's interest rate, because every dollar of principal you remove is a dollar that never accrues interest again. Investing offers the possibility of higher returns, but those returns are not guaranteed, and invested money generally stays more accessible than home equity. Your emergency fund, other debts, taxes, and timeline all matter. A financial advisor can weigh your full picture; Adam can run the mortgage-side numbers.
Work With Adam
Adam DeCraene — Mortgage Loan Originator, NMLS# 2811542, CA DRE #02448241 — with West Capital Lending, Inc. Run your loan's numbers above, then talk through whether extra payments, a refinance, or a HELOC fits your situation best — with access to 175 wholesale lenders behind the comparison.