Mortgage Extra Payment Calculator

FINANCE MORTGAGE PAYOFF
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By Checked against sources by , Founder & Architect, RECATOOLS Published Updated Last reviewed

Apply extra principal to your mortgage (monthly / annual / lump sum). See years off the loan + total interest saved + payoff date.

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Mortgage Extra Payment Calculator

⚠ Disclaimer: Estimates only. This calculator does not constitute financial, tax or legal advice, and RECATOOLS is not a licensed financial adviser in any jurisdiction. Rates, rules and product terms vary by country and change over time — check the figures against the relevant authority or provider, and consult a licensed adviser before making decisions.

Your mortgage

$

Extra principal payments (set any or all)

$
Added to every payment from month
$
Paid in loan month and every 12 months after
$
Paid in loan month
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How to use the Mortgage Extra Payment Calculator

Enter your current mortgage

Current balance (not original loan amount — your CURRENT balance), interest rate (the rate, not APR), and remaining term in years. For a 30-year loan with 2 years already paid, enter 28 years remaining.

Choose your extra-payment strategy

Three ways to accelerate, each combinable. Extra per month: simplest — add $100, $200, $500 to every monthly payment. Extra per year: paid in the loan month you choose (month 12 by default) and every 12 months after — e.g. a tax refund or year-end bonus. Lump sum: one-time large payment (inheritance, bonus, sale of asset).

Read years saved + interest saved

The hero number is years saved off the loan. The interest saved is total dollars NOT paid to the lender. On a $350K mortgage at 6.5% with 30 years to run, $200/month extra saves about 6 years and $108K in interest; with 28 years to run (the default above) it saves about 5.3 years and $92K.

Compare against investing instead

Critical question: is paying extra principal better than investing the same money? Rule of thumb: if your mortgage rate > your expected real investment return, payoff wins. At 7%+ mortgage rates, payoff almost always beats investing. At 3-4% mortgage rates with index investing, the math often favours investing. The tool gives you the payoff side; you compare against your alternative.

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Extra mortgage payments — the highest-leverage debt move most homeowners ignore

Every dollar of extra principal you pay on a mortgage skips ALL the future interest that dollar would have accrued. On a 30-year mortgage at 7%, $1 of extra principal paid in month one grows at the loan's rate for the remaining 359 months — (1 + 0.07/12)359 ≈ 8.1 — so it removes about $8 of future payments, roughly $7 of it interest. That saving is risk-free, immediate, and earned in after-tax dollars. Few financial moves match it, especially in high-interest-rate environments. The math is so elegant that aggressive payoff is one of the few cases where you can mathematically prove it's better than investing — when the mortgage rate exceeds your realistic investment return.

How extra payments compound

A standard 30-year mortgage at 6.5% on $350K has a monthly payment of about $2,212. Over 30 years you pay $796K total — $446K of which is interest. Now add $200 extra per month from day one. The accelerated payoff finishes after 286 payments instead of 360 — saving about 6.2 years and roughly $108K in interest. You committed an extra $57K of principal over those 23.8 years and avoided $108K of interest. Earlier payments compound more savings because they remove principal that would otherwise accrue interest for the longest time. $200/month in years 1-5 saves far more than $200/month in years 25-30.

On a 30-year mortgage at 7%, $1 of extra principal in month one removes about $8 of future payments — roughly $7 of it interest. Risk-free, immediate, and earned in after-tax dollars. Few financial moves match it.

The APAC mortgage angle

The amortisation arithmetic is the same everywhere; what differs is the rate you are paying and the alternative you would put the money into. In Singapore, extra repayment competes with the CPF Ordinary Account rate (2.5% for 1 October to 31 December 2026) and with any partial-redemption terms in a bank package; in Malaysia, with EPF dividends and fixed-deposit yields. The general rule holds in every market: the higher your mortgage rate relative to the safe return you could otherwise earn, the stronger the case for paying down.

When NOT to make extra payments

Three situations to skip the extra payment strategy. (1) You have higher-interest debt — a credit-card balance at several times your mortgage rate takes priority. (2) You don't have an emergency fund yet — extra mortgage payments are illiquid (you can't easily get the money back if you need it). Build 3-6 months emergency fund first. (3) Your mortgage rate is below what the money would earn elsewhere, after tax and risk — then every year you accelerate, you give up the difference. Run the comparison both ways and pick consciously.

A dollar of extra principal removes $8 of payments in year one, $1.42 in year 25

01

On a 30-year mortgage at 7%, $1 of extra principal in month one removes about $8 of future payments. The leverage fades as the loan ages: the same dollar in year 25 removes about $1.42.

02

The "bi-weekly trick": pay half the monthly amount every 2 weeks → 26 half-payments = 13 full payments per year. On a 30-year loan at mid-6% rates that removes roughly six years. See our Bi-Weekly Calculator.

03

US rules cap prepayment penalties on qualified mortgages at 2% of the amount prepaid in years one and two, 1% in year three, and nothing after that (12 CFR 1026.43(g)). Check your note before making large extra payments.

04

Extra payments must be designated as principal-only with most lenders — otherwise they may be applied as the next month's payment in advance. Always check your statement.

05

The US mortgage interest deduction covers interest on up to $750,000 of home-acquisition debt taken out after 15 December 2017 (IRS Publication 936) — and only if you itemise — so it can lower the after-tax rate the payoff earns.

06

In Singapore, CPF Ordinary Account savings (earning 2.5%) can pay down an HDB loan charged at 2.6% — a 0.10-point spread — while Special, MediSave and Retirement Account savings earn 4% (CPF Board and HDB, 1 Oct to 31 Dec 2026).

07

The "15-year refinance" achieves similar interest savings as extra payments but locks you into the higher monthly payment. Extra payments preserve flexibility (you can stop in lean months).

08

A $300K mortgage at 6% over 30 years saves about $91K in interest with $200/month extra — the borrower commits roughly $56K of extra principal over 23 years to avoid it, and finishes almost 7 years early.

09

In the 2020-2021 low-rate era — Freddie Mac's 30-year average bottomed at 2.65% in January 2021 — extra payments were mathematically weaker than investing, and many homeowners deliberately kept their mortgages.

10

Psychological argument for extra payments: debt-free is debt-free. Investing the extra produces a higher expected return but exposes you to market risk and behavioural risk (will you actually invest it consistently?). Payoff is guaranteed and certain.

📅 Research current as of 16 Oct 2026 · Sources: Schedule: RECATOOLS arithmetic in cents (MortgageKernel.extraPayments), checked against the CFPB sample Loan Estimate H-24(B). 12 CFR 1026.43(g) (prepayment penalties); IRS Publication 936 (2025); CPF Board, CPF interest rates (1 Oct to 31 Dec 2026); HDB, Interest Rate for HDB Housing Loan; Freddie Mac PMMS history; Damodaran, Historical Returns 1928–2025.
Rates, regulations, and lender practices change frequently — verify current figures with your provider or licensed advisor before acting.

Frequently Asked Questions

  • Depends on your mortgage rate vs realistic investment return. Rule of thumb: if mortgage rate > your expected real investment return, payoff wins. At 7%+ mortgage rates, payoff almost always beats investing. At 3-4% rates, investing often wins over long horizons — Damodaran's data (NYU Stern) put the S&P 500 with dividends at about 10% a year compounded over 1928–2025, before inflation, with deep falls along the way. Mixed approach: split the extra.

  • Yes, in almost all cases — but check for prepayment penalties first. For a US home loan covered by the ability-to-repay rule, a penalty is only permitted on a fixed-rate qualified mortgage that is not higher-priced, for at most three years, capped at 2% then 1% of the amount prepaid (12 CFR 1026.43(g)). Commercial loans and loans outside that rule can carry larger ones. ALWAYS designate extra payments as "principal only" — otherwise some lenders apply them as next-month-paid-ahead, which doesn't save you any interest.

  • EARLIER. At 7%, a $1 extra payment in month one of a 30-year mortgage removes about $8 of future payments; the same $1 in year 25 removes about $1.42. Earlier extra payments remove principal that would otherwise accrue interest for the longest remaining time. If you're 25 years into a 30-year mortgage, extra payments still save some money but the leverage is much weaker.

  • Refinancing changes the loan: new rate, new term. Extra payments keep the same loan but pay it faster. Refinancing makes sense when the monthly saving repays the closing costs well before you expect to move or refinance again; extra payments make sense when you can afford more than the minimum and want to pay down faster without committing to a new contract. Extra payments preserve flexibility (you can stop); refinancing locks in the new payment.

  • Yes if your mortgage rate exceeds the rate you'd get on tax-advantaged savings. Tax refunds are "found money" psychologically — easier to commit to mortgage payoff than to cut everyday spending. Enter the refund as a yearly extra in the month it usually arrives to see what it does on your loan.

  • Only if you itemise. The deduction covers interest on up to $750,000 of home-acquisition debt taken out after 15 December 2017 ($375,000 married filing separately; $1 million for older debt) (IRS Publication 936). For an itemiser it lowers the after-tax rate: a 6.5% rate at a 24% marginal bracket is effectively 4.94% (6.5 × 0.76). If you take the standard deduction, it does not apply at all.

  • CPF Ordinary Account savings can be used for a housing loan (CPF Board), and HDB accepts partial capital repayments. For 1 October to 31 December 2026 the OA pays 2.5% and HDB charges 2.6%, so paying the loan down from the OA gains 0.10% a year on that money while taking it out of your CPF; CPF's housing rules and limits apply, and money used for housing stops earning in CPF. Special Account savings earn 4% for the same quarter.

  • Some lenders allow "recasting" after a large lump sum — they recalculate the monthly payment to amortise the new lower balance over the remaining term, sometimes for a fee. Reduces your monthly payment without changing the rate or term. Useful after a big windfall + you want lower monthly burden vs faster payoff.

  • Because extra payment timing matters. A closed-form formula for "years saved" doesn't exist when you have multiple extra-payment types (monthly + annual + lump). Month-by-month simulation captures the exact amortisation correctly and works regardless of how you mix the three payment types.

  • No. All calculation happens entirely in your browser via JavaScript. Open DevTools → Network and watch — there's zero outbound traffic.

Method & sources

How it computes

Base payment P·r(1+r)^n ÷ ((1+r)^n − 1), r = rate ÷ 12, n = months left, rounded to the cent; two schedules in integer cents, interest = start-of-month balance × r (rounded): baseline, and with extra principal — monthly from a chosen month, yearly in a chosen loan month and every 12th after, a one-off lump — each applied with that month's payment. Months and interest saved are the differences; dates from the Singapore business day (MortgageKernel.extraPayments).

What this tool implements

  • Level-payment annuity with monthly compounding; all extras applied to principal in the month paid
  • Month-by-month simulation rather than a closed form, because mixed extra-payment types have no closed-form payoff
  • US tax and prepayment-penalty statements quote IRS Publication 936 and 12 CFR 1026.43(g)
  • Integer-cent schedule (RECATOOLS arithmetic), shared with /loan-amortization-schedule/ and /mortgage-calculator/: instalment and interest rounded half-up to the cent; extras applied entirely to principal with that month's payment; the loan ends in the month the balance plus interest fits in what is due, the last payment settling it to exactly 0. Month 1 is next month on the Singapore business day.
  • Worked figures re-derived from the kernel: $350,000 / 6.5% / 30 years → $2,212.24, $446,404 interest, $796,404 paid; +$200 a month → 286 payments, 6.2 years and $108,096 saved, $57,000 of extras; 28 years left → 5.3 years and $91,890; $300,000 / 6% / 30 years +$200 → 81 months, $91,174 saved, $55,600 of extras. $1 at 7% in month 1 → (1 + 0.07/12)^359 ≈ 8.07; with 60 months left ≈ 1.42.
  • Corrected 2026-10-16: floating-point schedules; blank term read as 30 years and blank lump month as 12; lump month past the loan accepted; yearly extra labelled "every December" (it is loan month 12, 24 …, now chosen); no payoff date shown; US deduction "capped at $750K post-2018" (IRS Pub 936: acquisition debt after 15 Dec 2017, $375,000 married filing separately, itemisers only); CPF rates dated Q3 (now 1 Oct–31 Dec 2026); "CPF SA should never be used for housing" (restated from CPF: OA savings pay a housing loan); "typically halves payoff time" removed; "~1% lower" refinance rule and "7% real return" removed; S&P "9.9%, ~7% after inflation" (Damodaran: about 10.0% compounded 1928–2025, before inflation).

Sources

What can make this go out of date

  • CPF OA/SA rates (quarterly); Freddie Mac PMMS history quoted in fact 09
  • none at runtime

Abridged — the full review record for this tool runs longer than the list above.

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