Finance
Mortgage Payoff Calculator
See how extra payments move up your payoff date and how much interest they save. Enter your balance, rate, and remaining term, then add an extra monthly amount, switch to biweekly, or drop in a lump sum — the baseline-versus-accelerated comparison updates live.
Strategy
Your mortgage
Add a fixed amount to every payment
What you still owe today
$
Your annual mortgage rate
%
Years left on the loan
yr
Added on top of your normal payment
$
Time saved
6 years 11 months
Interest saved
$103,449
Paid off in 23 years 1 month instead of 30 years
New 23y 1mBaseline 30y 0m
| Baseline | With extra | |
|---|---|---|
| Payment | $1,896.20 | $2,096.20 |
| Payoff | 30y 0m | 23y 1m |
| Interest | $382,633 | $279,185 |
| Total paid | $682,633 | $579,185 |
Try an example
No sign-up · Free
The basics
What paying off early actually does
A mortgage is front-loaded with interest: in the early years, most of each payment covers interest and only a sliver touches the principal. Every extra dollar you send goes straight to that principal, and because interest is charged on the balance, killing principal early erases all the future interest that balance would have generated. That is why a modest extra payment can save tens of thousands of dollars and years of payments.
interest = balance × monthly rate
Interest follows the balance
Interest each month is just the remaining balance times the monthly rate. Lower the balance faster and every future month's interest shrinks with it.
$300,000 × 0.0054 ≈ $1,625 in month one
extra → principal → less interest
Extra dollars compound in reverse
An extra payment removes principal that would otherwise accrue interest for the rest of the term. The earlier it lands, the more interest it cancels.
$100 extra now saves far more than $100 later
Method
How the calculation works
Two amortization schedules — one baseline, one accelerated — run side by side, and the difference is your savings.
- 1
Find the baseline payment
From your balance, rate, and remaining term, the standard amortization formula gives the fixed monthly payment that clears the loan exactly on schedule.
M = P·r(1+r)ⁿ ÷ ((1+r)ⁿ − 1) - 2
Run the baseline schedule
Each month, interest is the balance times the monthly rate; the rest of the payment reduces the balance. Repeat until it reaches zero to get the payoff time and total interest.
interest = balance·r; balance −= (M − interest) - 3
Run the accelerated schedule
Do the same, but add your extra to each payment (or a lump sum up front). The bigger payment kills principal faster, so the balance hits zero sooner.
balance −= (M + extra − interest) - 4
Subtract to get the savings
The gap between the two payoff times is your time saved; the gap between the two interest totals is your interest saved.
saved = baseline − accelerated
Worked examples
See it across strategies
The same loan, paid down three different ways. Each tab computes the baseline and the accelerated payoff from the numbers shown.
A typical new 30-year loan. Adding $200 to every payment is the most common strategy.
Given balance = $300,000, rate = 6.5%, term = 30 years
Baseline payment: $1,896.20 → paid off in 30 years
Total interest, baseline: $382,633
With this strategy: paid off in 23 years 1 month, interest $279,185
saves 6 years 11 monthssaves $103,449 interest
Same loan, same formula — only the extra payment changes. Earlier and larger extras save the most, because they kill interest that would otherwise compound for years.
Quick chart
How much does $X extra a month save?
Every common extra payment on a typical 30-year loan, with the new payoff time and the interest it saves. Pick the loan closest to yours and read the row — the answer to “what does an extra $200 a month do?” in one place.
30-year loan
| Extra / month | New payoff | Time saved | Interest saved |
|---|---|---|---|
| +$50 | 27y 10m | 2y 2m | $33,582 |
| +$100 | 26y 0m | 4y 0m | $60,995 |
| +$150 | 24y 5m | 5y 7m | $83,919 |
| +$200 | 23y 1m | 6y 11m | $103,449 |
| +$250 | 21y 10m | 8y 2m | $120,337 |
| +$300 | 20y 10m | 9y 2m | $135,115 |
| +$400 | 19y 0m | 11y 0m | $159,832 |
| +$500 | 17y 6m | 12y 6m | $179,759 |
| +$750 | 14y 9m | 15y 3m | $216,223 |
| +$1,000 | 12y 9m | 17y 3m | $241,162 |
Strategies
Four ways to pay it down faster
Every approach does the same thing — sends more to principal — but each suits a different budget and temperament.
add a fixed amount
Extra monthly payment
The simplest and most flexible: tack a set amount onto every payment. You control the size, and you can stop or change it any time. Mark it as principal-only so it actually shortens the loan.
half-payment every 2 weeks
Biweekly payments
Paying half your monthly amount every two weeks yields 26 half-payments — 13 full payments a year, one more than the usual twelve. It is painless because it tracks a biweekly paycheck, but confirm the servicer applies the halves correctly rather than holding them.
one big payment now
Lump sum
A bonus, tax refund, or inheritance applied to principal early erases the most future interest. Timing matters: the same lump saves far more in year two than in year twenty.
round up to the next $100
Round-up payments
Round a $1,847 payment up to $1,900 and the extra $53 quietly chips away at principal without a noticeable budget hit — the easiest habit to keep.
Worth weighing
When paying extra isn't the best move
Prepaying a mortgage is a guaranteed return equal to your rate — but it is not always the highest-value use of a dollar. A few factual trade-offs to weigh (general information, not personalized advice).
opportunity cost
Higher-return uses exist
Prepaying earns a guaranteed return equal to your interest rate. If your rate is low, a diversified investment or a tax-advantaged retirement match may reasonably be expected to earn more over time — though without the same certainty.
clear costlier debt first
High-interest debt comes first
Credit cards and many personal loans charge far more than a mortgage. A dollar saves more interest on a 22% card than on a 6% mortgage, so those balances usually deserve the extra payment before the home loan does.
keep cash on hand
Emergency fund matters
Money sent to the mortgage is hard to get back without a refinance or sale. An adequate emergency fund and liquidity should generally come before locking cash into home equity.
lost liquidity & deductions
Liquidity and tax effects
Home equity is illiquid, and for those who itemize, mortgage interest can be partly deductible — slightly lowering the real cost of carrying the loan. Factor both into the comparison.
Worth knowing
Common mistakes and pitfalls
A handful of errors that quietly waste the effort of paying extra.
not principal-only
Extra not applied to principal
An unlabeled extra payment is often booked as next month's payment, not a principal reduction, so the loan never shortens. Always specify “principal only.”
confusing recast & prepay
Expecting a lower payment
Extra payments shorten the term, not the required monthly amount. Only a recast or refinance lowers the payment itself.
ignoring penalties
Overlooking a prepayment penalty
Most loans have none, but some older or non-conforming mortgages charge one in the early years. Check the loan documents before a large payment.
waiting too long
Starting late
Because interest is front-loaded, extra payments in the early years save dramatically more than the same payments near the end. Sooner beats bigger-but-later.
emptying the buffer
Draining savings to prepay
Locking every spare dollar into equity leaves nothing for emergencies. Keep a cash cushion before accelerating the mortgage.
forgetting escrow
Counting escrow as principal
Your payment also funds taxes and insurance through escrow. Only the principal-and-interest portion amortizes — extra must target principal specifically.
Related tools
Where to go next
This calculator focuses on the savings from extra payments. To see the full payment-by-payment picture or the flip side of compounding, these go deeper.
full schedule
Amortization calculator
Want every line of the schedule — principal and interest for each payment, with the balance ticking down? The amortization calculator builds the complete table from your loan amount, rate, and term.
the other side
Compound interest calculator
The same compounding that costs you interest on a mortgage works for you when you invest. The compound interest calculator shows what the money would grow to instead — useful for the prepay-versus-invest question.
How we calculate this
The formula and our assumptions
We build the baseline payment from the standard amortizing-loan formula, then simulate the loan month by month with your extra payments applied straight to principal. We show the working so you can check it.
M = P·r ÷ (1 − (1 + r)^−n)
The baseline payment
P is the balance you still owe, r the annual rate divided by twelve, and n the number of payments left. This is the scheduled payment before any overpayment.
balance −= (payment − interest)
The month-by-month simulation
Each month the interest is the balance times r; the rest of the payment cuts the balance. Every extra dollar goes straight to principal, so it removes the interest that dollar would have carried for the rest of the loan.
- The rate is fixed for the remaining term; adjustable-rate loans are not modelled.
- A biweekly plan is half the monthly payment every two weeks — 26 half-payments, about one extra full payment a year.
- Extra payments apply to principal in the month they are made.
- We assume no prepayment penalty — check your note, as a few loans still carry one.
- This models principal and interest only; escrowed tax and insurance are not part of the payoff math.
Where to refinance
Where to lower the rate on the balance
Overpaying is one lever; refinancing to a lower rate is the other. Rows are ordered by borrower fit, not by any payout — the type that suits your situation comes first for you. Rates are shown as ranges only; get an exact quote from the lender, because pricing depends on your credit, the home and the day.
| Where | Examples | Best for | Typical pricing |
|---|---|---|---|
| Online marketplace | LendingTree, Credible | Comparing several refinance quotes from one form | Market range |
| Your current servicer | Whoever you pay now | A recast or streamline without a full refinance | Low or no fee |
| Credit union | Member-owned lenders | Lower fees and member pricing | Often below market |
| Direct lender / bank | Rocket, Chase, local banks | An existing banking relationship | Market range |
CalculateThis.io is not a lender and does not make credit decisions. When we add lender links they will be marked as sponsored, and we may earn a commission if you apply through one — it does not change the rate you are offered.
Sources
Where the method comes from
- Consumer Financial Protection Bureau — paying down your mortgage, prepayment and recasting.
- Freddie Mac Primary Mortgage Market Survey — historical mortgage-rate context for refinancing.
- Standard amortization formula for a fixed-rate, fully amortizing loan.
FAQ
Common questions
It depends on the balance, rate, and how long is left, but the effect is large because every extra dollar goes straight to principal and erases the interest that dollar would have generated for the rest of the loan. On a $300,000 balance at 6.5% over 30 years, an extra $100 a month pays the loan off roughly four years early and saves on the order of $70,000 in interest. Use the calculator with your own numbers — the savings scale with the balance and the rate.
Only if you tell the servicer to apply them to principal. An extra amount sent without instruction is often treated as a prepayment of the next scheduled payment, which does not shorten the loan. Most lenders let you mark an extra payment as 'principal only' online or by memo. This calculator assumes every extra dollar reduces principal — confirm your servicer does the same.
Biweekly payments — half your monthly payment every two weeks — add up to 26 half-payments a year, which equals 13 monthly payments instead of 12, so you make one extra payment a year automatically. A fixed extra each month gives you more control and can be larger or smaller than that one-payment-a-year equivalent. The math is the same: both just send more to principal. Pick whichever you will actually stick to.
A lump sum applied early is powerful because it removes principal before years of interest can accrue on it — the earlier it lands, the more interest it kills. A steady monthly extra eventually moves more total dollars but starts smaller. If you have a windfall, applying it now usually beats spreading the same amount over many months.
Paying down a mortgage is a guaranteed, tax-free return equal to your interest rate. Investing might earn more over the long run but is not guaranteed. As a rough rule, if your mortgage rate is higher than what you could reliably earn after tax, prepaying wins; if your rate is low and you have higher-return options or unpaid high-interest debt, those usually come first. This is general information, not personalized financial advice.
Most modern U.S. mortgages have no prepayment penalty, but some older or non-conforming loans do — typically within the first few years. Check your loan documents for a 'prepayment penalty' clause before making large extra payments. Even where a penalty exists, it is usually a percentage of the balance or a few months of interest, which the long-term interest savings can still outweigh.
No. Extra payments shorten the loan term but leave your required monthly payment the same — you simply finish sooner. To lower the required payment you would need to refinance or ask your servicer for a 'recast', where they re-amortize the loan over the remaining term after a large principal payment. A recast lowers the payment; extra payments shorten the schedule.
We compute your normal monthly payment with the standard amortization formula, then run two month-by-month schedules: a baseline that pays exactly that amount, and an accelerated one that adds your extra. Each month, interest equals the balance times the monthly rate, the rest of the payment reduces the balance, and we repeat until the balance reaches zero. The difference in the number of months is your time saved, and the difference in total interest is your interest saved.
Keep going
Related calculators
Keep reading
Further reading
Calculator
Gross vs Net: The Difference, With Dollar Examples
Gross is the total before deductions; net is what is left after deductions are subtracted. This guide explains gross vs net for pay, income, and profit with worked dollar examples and a quick comparison table.
Ugo Charles
Calculator
How to Write a Check: A Step-by-Step Guide
Writing a check takes six fields: the date, the payee, the amount in numbers, the amount in words, an optional memo, and your signature. This guide walks every field with one worked example and shows exactly how to write the cents.
Ugo Charles
Finance
The Compound Interest Formula: A = P(1 + r/n)^(nt), Explained
The compound interest formula is A = P(1 + r/n)ⁿᵗ, where P is the starting principal, r is the annual rate as a decimal, n is the number of times interest compounds per year, t is the number of years, and A is the final amount. This guide defines each variable, works a full example, and shows how compounding frequency changes the result.
Ugo Charles
Written by
UC
Author
Ugo CharlesBuilt and fact-checked against our editorial standards · Last updated June 2026
Did this solve your problem?