Mortgage Extra Payment Calculator
Compare the original payoff schedule with an accelerated plan while keeping the regular principal-and-interest payment visible.
Verify this calculatorMaintained
See what the result uses—and what it cannot know.
Sumvoro calculates deterministically from the visible inputs. It does not invent lender terms, local rules, market values, medical facts, or professional judgments.
- 1 · InputsCheck every entered value against the latest statement, quote, measurement, or official source.
- 2 · Formula
The scheduled payment follows fixed-rate amortization; extra payments reduce principal after each month’s interest is calculated. - 3 · SensitivityUse Insights to run a lower and higher case. If the conclusion changes easily, collect better information or leave more margin.
- 4 · ScopeThis tool is maintained and covered by automated calculation tests. Provider timing, rounding, and omitted facts can still change a real-world result.
- Formula release
- 2026.10-r4
- Release date
- October 10, 2026
- Review status
- Maintained
- Source review
- September 12, 2026
Optional readingLearn how this calculator works
How the mortgage extra payment calculator works
See how recurring and one-time extra principal payments can shorten a mortgage and reduce interest.
The scheduled payment follows fixed-rate amortization; extra payments reduce principal after each month’s interest is calculated.
Read our calculation methodology and limitations.
Example
Adding $250 monthly to a 30-year mortgage can remove years of payments and materially reduce lifetime interest.
What affects the result
- Confirm that your servicer applies extra money to principal.
- Prepayment terms vary by mortgage.
- Taxes, insurance, and escrow are excluded because extra principal does not reduce them.
Frequently asked questions
Does this include escrow?
No. The comparison focuses on principal and interest because taxes and insurance generally continue independently.
Can I add a lump-sum payment?
Yes. Enter the one-time amount and the month when it will be applied.