A walkthrough, end to end.
- 1
Enter your current loan balance, rate, remaining term, and the extra monthly principal you'll add.
- 2
The calculator compares the original payoff timeline against the accelerated one.
- 3
See years saved, total interest saved, and the new payoff date.
Accelerated payoff math
Same amortization formula, but with each month's payment increased by the extra amount. The extra goes 100% to principal, reducing the balance faster than the schedule. Less balance → less interest accrual → exponentially faster payoff.
What you can do with this.
Extra $100 per month
On a $300K, 30-year, 7% mortgage, an extra $100/mo cuts 4 years off the term and saves about $66K in interest. Small consistent additions compound dramatically.
Extra $500 per month
Same loan with $500/mo extra: cuts ~12 years off, saves ~$155K in interest. The leverage of paying down high-balance early years is enormous.
One-time annual lump sum
A single $5,000 annual prepayment (e.g. tax refund) on a 30-year mortgage saves ~$70K total interest and shaves ~4 years. Often easier to commit to than monthly extras.
Biweekly payment strategy
Half your monthly payment every 2 weeks = 13 monthly equivalents per year. Free 7-year speedup with no per-payment increase. Many lenders charge fees to enroll — DIY by sending the extra yourself.
Round up to next $100
Payment of $1,847? Round to $1,900. The extra $53/mo on a 30-year, 7% loan saves ~$36K interest and 2.5 years. Simple, sustainable, low-friction.
Should I pay extra or invest?
If your mortgage rate is below ~5%, investing typically wins long-term (7%+ historical returns). Above ~6%, the math leans toward paying down. 5–6% is a coin-flip; depends on risk tolerance.
Refinance vs. pay extra
Refinance lowers required payment; extra principal speeds payoff at the current payment. Combine: refinance to a lower rate, then keep paying the old higher payment as 'extra' — best of both.
Mortgage payoff 2026 — what's current
With current rates 6.5–7%, the math overwhelmingly favors prepayment for most borrowers — every extra dollar earns ~7% guaranteed (the rate you avoid). Hard to beat with risk-free investments.
Frequently asked.
Mainly opportunity cost — that money can't be invested elsewhere. Also liquidity: prepaid principal can't be re-borrowed without a refinance or HELOC.
By default usually yes, but ALWAYS write 'apply to principal' in the memo. Some lenders apply extra to next month's payment instead — that doesn't speed up payoff.
Most modern US mortgages have no prepayment penalty. Check your loan documents — older or specialty loans sometimes have them, typically expiring after 3–5 years.
No. Calculations run entirely in your browser.