How much can an extra payment actually save?

On a 30-year $300,000 loan at 7%, an extra $200/month pays off 6 years early and saves roughly $100,000 in interest. The later in the loan you are, the less each extra dollar saves — early payments matter most because interest front-loads.

Is it better to invest extra money or pay down the mortgage?

Rough math: if your mortgage rate is 7% and you expect 8-10% on stock investments, investing wins long-term. But paying down mortgage is a guaranteed 7% return — no market risk. Many people do both: max retirement accounts first, then split.

What is a biweekly payment schedule?

Pay half the monthly payment every two weeks. Because there are 26 biweekly periods in a year, you make 13 full monthly payments instead of 12 — one extra payment annually. This alone cuts a 30-year loan to about 26 years.

Will my lender let me make extra principal payments?

Yes, in nearly all cases. Check your loan terms for 'prepayment penalties' — uncommon since 2010 but they exist. Send extra payments with a note specifying 'apply to principal' so they don't get credited against your next regular payment.

Should I refinance instead of prepaying?

Different decisions. Refinance changes your rate (lower rate = lower monthly payment but you start the amortization clock again, often 30 more years). Prepayment changes your timeline (same rate but pays off faster). Best of both: refinance to lower rate AND keep paying the higher original payment — that's effectively prepayment of the new lower-rate loan. Run both scenarios — sometimes refinance + prepayment beats either alone, especially if rates dropped 1.5%+ since you originated. Closing costs on refi are $3-6K typically; break-even is usually 18-36 months.

What's the order of operations for paying down debt vs other financial goals?

(1) Cover essentials and have a starter emergency fund ($1-2K). (2) Max employer 401k match (free money — typically 50-100% return). (3) Pay off high-interest debt (credit cards 18-25%, personal loans 10-15%). (4) Build full emergency fund (3-6 months expenses). (5) Max Roth IRA and 401k contributions. (6) Pay down medium-rate debt (mortgage at 6-7%, student loans 5-7%) OR invest in taxable brokerage — depending on rate vs expected return. (7) Other financial goals (529 for kids, second properties, etc.). Mortgage prepayment is rarely #1; it's usually optimal at step 6 after tax-advantaged accounts are full.

Money & Finance · Free tool

Mortgage Payoff Accelerator

Calculate how adding $100 or more to monthly payments can slash your mortgage timeline and total interest. A free, instant, no-sign-up online tool to weigh your options.

Updated June 2026

Loan balanceInterest rate %Original term (years)Extra payment per month

Standard payoff

Jun 2056

Accelerated payoff

Jan 2049

Time saved

7 yr 5 mo

Interest saved

$137,695

Impact of different extra payments

Extra / month	Payoff in	Years saved	Interest saved
$100	26 yr 5 mo	3.6	$68,618
$250	22 yr 7 mo	7.4	$137,695
$500	18 yr 5 mo	11.6	$209,212
$1,000	13 yr 8 mo	16.3	$285,780

Base monthly P&I: $2,293. Extra principal goes directly against the balance — the earlier you add it, the more interest you avoid.

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What it does

See exactly how much extra principal payment shortens your mortgage and how much interest you save. Tool runs the amortization with and without your extra-payment plan, showing months saved and dollar interest saved. On a 30-year $300,000 loan at 7%, an extra $250/month pays off about 7 years early and saves ~$120,000 in interest. Earlier extra payments save more (interest front-loads on amortizing loans), so $250/month starting in year 1 saves dramatically more than the same $250/month starting in year 15.

The math: every dollar of extra principal payment skips that dollar’s worth of future interest. On a 7% loan, an extra $1,000 paid in year 1 saves ~$5,000 in interest over the remaining loan life (compounding effect). Same $1,000 paid in year 20 saves only ~$700. This is why “round up your payment” or “biweekly schedule” strategies work so well — they front-load extra principal during the highest-interest years. Biweekly (paying half-payment every 2 weeks) results in 26 biweekly = 13 full monthly payments per year, an automatic 1-extra-payment-per-year acceleration without consciously allocating extra cash.

Decision framework — when to prepay vs invest: Prepay if: mortgage rate is over your expected investment return after tax, you value certainty, you’re near retirement (don’t want loan in retirement). Invest if: rate is under expected investment return, you have years of time horizon, you’re maxing tax-advantaged accounts already. With a 7% mortgage and 8-10% expected stock returns, investing wins long-term but adds market-risk volatility. With a 3-4% mortgage (pre-2022 borrowers), investing wins more easily. Most CFP-recommended approach: (1) build emergency fund, (2) max employer 401k match, (3) pay high-interest debt, (4) max Roth IRA + 401k, (5) THEN consider mortgage prepayment vs taxable investing. Mortgage prepayment as the first move is usually a mistake — it’s the safest of financial moves but rarely the most profitable.

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How to use it

Enter your current mortgage balance (not original loan amount).
Enter your interest rate (current rate; check your monthly statement).
Enter remaining term in years (typical: 20-29 if started a 30-year recently).
Enter extra principal payment per month (the additional amount above your regular P&I).
Read months saved (typical: 60-100 months for $200-300/month extra) and total interest saved (typical: $60K-130K on a $300K loan).
Compare scenarios: try $100, $200, $500/month extra to find the right balance between accelerated payoff and other financial goals.

When to use this tool

High-rate mortgage (over 6%) where the guaranteed 'return' of avoided interest beats expected investment returns after tax.
Within 10-15 years of retirement when you want to be mortgage-free in retirement (reduces required income in fixed-income years).
After maxing employer 401k match + Roth IRA + emergency fund — when prepayment is a tax-efficient remaining option for surplus savings.
When you have low risk tolerance and prefer guaranteed savings to market-tied investment returns.

When not to use it

Low-rate mortgage (under 4%) where investing in index funds typically beats the avoided interest.
When you don't have an emergency fund — mortgage prepayment is illiquid; you can't easily get the money back if needed.
When you have higher-interest debt (credit cards 18-25%, personal loans 8-12%) — pay those off first.
When you haven't maxed tax-advantaged accounts (401k, Roth IRA, HSA) — those usually beat mortgage prepayment for after-tax wealth building.

Common use cases

Verifying a number or output before passing it on
Quick use during a typical workday
Pre-decision sanity-check on inputs and outputs
Educational use — demonstrating the underlying concept

Frequently asked questions

How much can an extra payment actually save?: On a 30-year $300,000 loan at 7%, an extra $200/month pays off 6 years early and saves roughly $100,000 in interest. The later in the loan you are, the less each extra dollar saves — early payments matter most because interest front-loads.
Is it better to invest extra money or pay down the mortgage?: Rough math: if your mortgage rate is 7% and you expect 8-10% on stock investments, investing wins long-term. But paying down mortgage is a guaranteed 7% return — no market risk. Many people do both: max retirement accounts first, then split.
What is a biweekly payment schedule?: Pay half the monthly payment every two weeks. Because there are 26 biweekly periods in a year, you make 13 full monthly payments instead of 12 — one extra payment annually. This alone cuts a 30-year loan to about 26 years.
Will my lender let me make extra principal payments?: Yes, in nearly all cases. Check your loan terms for 'prepayment penalties' — uncommon since 2010 but they exist. Send extra payments with a note specifying 'apply to principal' so they don't get credited against your next regular payment.
Should I refinance instead of prepaying?: Different decisions. Refinance changes your rate (lower rate = lower monthly payment but you start the amortization clock again, often 30 more years). Prepayment changes your timeline (same rate but pays off faster). Best of both: refinance to lower rate AND keep paying the higher original payment — that's effectively prepayment of the new lower-rate loan. Run both scenarios — sometimes refinance + prepayment beats either alone, especially if rates dropped 1.5%+ since you originated. Closing costs on refi are $3-6K typically; break-even is usually 18-36 months.
What's the order of operations for paying down debt vs other financial goals?: (1) Cover essentials and have a starter emergency fund ($1-2K). (2) Max employer 401k match (free money — typically 50-100% return). (3) Pay off high-interest debt (credit cards 18-25%, personal loans 10-15%). (4) Build full emergency fund (3-6 months expenses). (5) Max Roth IRA and 401k contributions. (6) Pay down medium-rate debt (mortgage at 6-7%, student loans 5-7%) OR invest in taxable brokerage — depending on rate vs expected return. (7) Other financial goals (529 for kids, second properties, etc.). Mortgage prepayment is rarely #1; it's usually optimal at step 6 after tax-advantaged accounts are full.

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