Interactive tool · Free · Updated for 2026

Extra Payment Mortgage Calculator

See how extra payments, bi-weekly, and lump sums cut years off your mortgage.

Test any combination of extra-payment strategies (monthly, extra payments per year, bi-weekly, or a one-time lump sum), see exactly how many years come off, and get the refinance-equivalent rate your plan works out to.

  • 3 extra-payment types
  • Effective-rate verdict
Calculate now How it works
Save
Live calculation
runs locally
see two plans side by side
Loan basics
Loan balance
Interest rate
%
Extra monthly payment
Extra monthlyadded to every payment, straight to principal
Interest saved
$116.6K
27.9% of lifetime interest · 7 yr 1 mo sooner
Monthly P&I
30-yr schedule
$1,996
New payoff date
was Aug 2056
Jul 2049
Total payments cut
over the loan lifetime
$116.6K
Plan works like a rate of
vs your actual 7.00%
5.33%
Effective-rate verdict
Your plan works like refinancing from 7.00% to 5.33%, without closing costs.

A no-extras loan of $300.0K over 30 years would need a 5.33% rate to match the $301.9K of total interest your plan pays. Extra payments buy that rate cut with no application, no appraisal, and no fees, and you can stop any month.

Suggested plans

What each extra-payment level buys you.

$100/mo extra
Interest saved
$69.3K
Debt-free byJun 2052
Total paid$649.2K
Extra monthly$100
$250/mo extra
Interest saved
$135.3K
Debt-free byApr 2048
Total paid$583.2K
Extra monthly$250
$500/mo extra
Interest saved
$200.2K
Debt-free byDec 2043
Total paid$518.3K
Extra monthly$500
What moves this result

Which extra payment earns the most, ranked.

Left alone, this loan costs 140% of the principal in interest. Your plan already cuts that by 28%, and the moves below show where the next push pays off most.
Switch on bi-weekly payments (13 full payments a year)Biggest impact
debt-free 3 yr 6 mo sooner
+$53.5K saved
Make one extra full payment each year
$1,996 to principal every December, debt-free 3 yr 5 mo sooner
+$50.9K saved
Add $100 more to every monthly payment
debt-free 2 yr 4 mo sooner
+$34.9K saved
Refinance your rate down to 6.50%
or negotiate with your current lender
+$22.7K saved
Add $2.5K to your one-time lump sum
applied at month 12, debt-free 6 mo sooner
+$8.8K saved
Balance comparison
With and without extra payments
Side-by-side

Without extras vs. with your plan.

Metric
Without extras
With your plan
You save
Loan duration
30 yr
22 yr 11 mo
7 yr 1 mo sooner
Total interest
$418.5K
$301.9K
$116.6K
Total paid
$718.5K
$601.9K
$116.6K
Debt-free by
Aug 2056
Jul 2049
-
Interest as % of principal
140%
101%
−39 pp
Shareable

Share your extra-payment plan.

The PDF report ranks every extra-payment lever with your real numbers; the savings card downloads as a PNG for a quick brag.

The PDF carries your inputs, results, and scenarios, plus a link that re-opens this calculator with everything pre-filled.

lazysmirkextra-payment-mortgage-calculator
My extra-payment plan
Saving $116.6K
7 yr 1 mo earlier · debt-free by Jul 2049.
Balance
$300.0K
Rate
7%
Extra
$200/mo
lazysmirk.comBuild less. Win more.
Quick Answers

Extra Payment, in 30 seconds.

Direct answers to the most common questions, in plain language. Skim if you're in a hurry; dig deeper below.

What happens if I pay an extra $200 a month on my mortgage?

Answer

On $300k at 7% for 30 years: about $116,600 saved, paid off 7 years early.

Running this calculator's own amortization on a $300,000, 30-year loan at 7%: an extra $200/month saves about $116,640 in interest and clears the loan 85 months (just over 7 years) early, in roughly 23 years instead of 30. That plan produces the same lifetime interest as a no-extras loan at about 5.33%, so it works like a 1.7-point refinance with zero closing costs.

How much does an extra mortgage payment save?

Answer

$100/mo extra typically saves 4–6 years and 20–30% of interest.

On a 30-year, $300k mortgage at 7%, an extra $100/month cuts the loan by about 5 years and saves roughly $80,000 in interest. The savings scale roughly linearly with the extra amount.

Is bi-weekly payment the same as one extra monthly payment?

Answer

Yes, and it's 13 months of payments per year, not 12.

Paying half your mortgage every 2 weeks results in 26 half-payments per year, equivalent to 13 full monthly payments. That one extra payment per year shaves 4–5 years off a typical 30-year mortgage.

Should I pay extra or refinance?

Answer

Refinance for rate drops; extra payments for accelerated payoff.

Refinancing makes sense if rates drop 0.75%+ and you'll stay in the home long enough to recoup closing costs. Extra payments work at any rate; they're a guaranteed return equal to your mortgage rate.

Is there a penalty for extra mortgage payments?

Answer

Almost never on US conventional, FHA, or VA loans.

Federal regulations effectively prohibit prepayment penalties on most owner-occupied conventional, FHA, VA, and USDA loans. Some non-conforming or older loans may have penalties; check your note.

How it works

How extra payment works.

The mechanics in short answers. No jargon, no upsell.

01

Extras attack the principal directly.

Anything paid above your scheduled P&I goes 100% to principal. The next month's interest calculation uses the new, lower balance.

02

Early years matter most.

In year 1 of a 30-year loan, 75% of your payment is interest. An extra dollar in year 1 saves far more than the same dollar in year 25.

03

Bi-weekly = 1 extra payment per year.

26 half-payments per year ≠ 24. The "extra two halves" become one full extra payment that goes straight to principal.

04

Lump sums front-load the payoff.

A $10,000 tax refund applied to principal in year 3 saves dramatically more than spreading it out; earlier is always better.

The math behind it

Full transparency
EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
Each month: interest = balance × r; everything above interest (including your extra) reduces the balance
Interest saved = total interest (no extras) − total interest (with extras)
P
loan balance (amount borrowed)
r
monthly interest rate = annual rate ÷ 12 ÷ 100
n
total number of monthly payments (years × 12)
extra
extra monthly amount + extra full payments each year (× EMI) + bi-weekly equivalent (EMI ÷ 12) + one-time lump sum at month 12

Worked example: On a $300,000 loan at 7% for 30 years the EMI is about $1,996. Adding the default $200/mo extra saves roughly $117,000 of interest, pays the loan off about 7 years sooner, and costs the same lifetime interest as a no-extras loan at about 5.33%.

Both schedules are simulated month by month (extra yearly payments land each December, the bi-weekly option is modeled as its monthly equivalent, EMI ÷ 12 extra, and the lump sum lands at month 12) rather than using a closed-form shortcut. The effective rate is found by binary-searching the rate at which a no-extras loan matches your plan's total interest. Everything runs locally in your browser; your numbers never leave this page.

How to use

Four steps. About 20 seconds.

Designed so anyone can model their situation in under a minute, with or without a finance background.

  1. Step 1
    Enter loan details
    Current balance, rate, and remaining years.
  2. Step 2
    Add extra payment strategy
    Monthly extra, bi-weekly, or yearly lump sum; combine any.
  3. Step 3
    See the payoff date
    Years and months saved, plus the new debt-free date.
  4. Step 4
    Compare scenarios
    Toggle strategies to see which saves the most.
Benefits

Why this matters.

Cut years off the loan

Even modest extras shorten the loan by years; see the exact months.

Save massive interest

Tens of thousands over the life of the loan, guaranteed return at your rate.

Test multiple strategies

Monthly extra, bi-weekly, one extra payment per year, lump sum: compare all four.

See the payoff date move

Watch your debt-free date slide forward in real time.

No risk

Extra payments are a guaranteed return: no market exposure, no fees, no taxes.

Plan around life

Pause or accelerate extras any month, flexibility that refinance doesn't offer.

FAQ

Extra Payment, answered.

Everything you might ask before, during, or after using this tool.

Written for borrowers, not bankersPlain-language, jargon-freeReviewed quarterly
Should I pay extra principal or invest the money?

A guaranteed 7% return (your mortgage rate) is hard to beat after taxes and risk. If your mortgage rate is below ~5%, investing in equities often wins long-term. If above ~6.5%, extra payments usually win. Around 5.5–6.5% is the messy middle, and many people do both.

Does the bank reduce my monthly payment after extras?

No; most lenders apply extras to principal but keep your monthly payment the same and shorten the loan. To "recast" (reduce the monthly), you usually pay a small fee ($250–500) and request it explicitly. Most borrowers don't recast because shortening the loan saves more interest.

Is bi-weekly always better than monthly?

Yes, slightly: bi-weekly results in one extra payment per year, plus the timing means interest is calculated on a slightly lower balance throughout the year. Total savings vs. straight monthly is usually 4–5 years and 15–20% interest reduction.

Should I make a big lump-sum payment from a bonus?

Almost always yes, assuming your high-interest debt is paid off and emergency fund is funded. A $10,000 lump sum applied to a 7% mortgage in year 3 saves roughly $25,000 in interest over the remaining loan.

Do I need to tell my lender it's an extra payment?

Yes; be explicit. Write "apply to principal" on a check, or use the principal-only option in online banking. Otherwise some servicers credit it as "next month's payment," which costs you interest savings.

What about my tax deduction?

Mortgage interest deduction matters less than it used to. After the 2017 SALT cap, most homeowners take the standard deduction and lose the mortgage-interest benefit anyway. Even with the deduction, the math typically still favors paying extra.

How much do I need to pay extra to cut 10 years off?

On a 30-year, $300k loan at 7%, paying about $400/month extra cuts the loan by roughly 10 years. The exact amount scales with loan size and rate; use this calculator with your specific inputs to find your target.

Should I pay extra or build my emergency fund first?

Emergency fund first, always. A 3–6 month fund is non-negotiable. Once that's funded, extra payments become a powerful tool. Skipping the fund to pay extra is fragile; one job loss undoes years of acceleration.

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The math of extra payments

Interest is calculated on remaining principal every month. Pay an extra $200 in year 2 of a 30-year loan and you erase $200 of principal that would have accrued interest for 28 more years.

That compounding-against-you-not-happening is where the savings come from. It's identical math to compound investing, just running in your favor.

The four extra-payment strategies

Monthly extra: simplest, most flexible. Pick an amount and add it to every payment.

Bi-weekly: 13 monthly payments per year instead of 12. Hands-off acceleration.

Annual extra payment: send one extra full payment each year, usually January.

Lump sum from bonus/refund: rare but powerful, since the earliest dollars matter most.

Recast vs shorten

Default behavior: extras shorten the loan, monthly payment stays the same.

Recast: for a small fee, the lender re-amortizes the loan with the new lower balance; your monthly payment drops, but the savings are smaller than just letting the loan shorten.

Pick shorten unless you actively need lower monthly cash flow.

Extra payment vs invest

Math: compare your mortgage rate to your after-tax expected investment return.

Below 5%: investing usually wins long-term.

Above 6.5%: extra payments usually win.

5.5–6.5%: muddy. Many people split 50/50.

Don't ignore the behavioral angle: guaranteed savings feels different from variable returns. That matters.

Common extra-payment mistakes

  • Not specifying "apply to principal", so the payment gets credited to next month.
  • Paying extra before killing higher-rate debt (credit cards, personal loans).
  • Recasting when shortening would save more.
  • Stretching to pay extra at the cost of retirement contributions.
  • Paying extra without an emergency fund.
Trust & transparency

How this tool behaves, and what it isn't.

Two short notes worth reading before you trust any number on this page.

Privacy

Calculations run locally in your browser.

Your loan amount, rate, and prepayment inputs never leave your device. No accounts, no cookies on your numbers, no analytics on the values you type. Disconnect from the internet and it still works.

  • No account required
  • No data stored or sent
  • Works offline
  • No third-party trackers
Disclaimer

Lazysmirk is a tools platform, not a financial institution.

We are not a bank, NBFC, advisor, broker, or distributor of any financial product. The numbers shown here are estimates for educational purposes only, based on the inputs you provide.

Results are not financial, legal, or tax advice. Please consult a qualified professional before any decision about your loan, investments, or personal finances. Actual loan terms and charges depend on your bank and individual circumstances.