See what extra payments do to your payoff date and lifetime interest.
How to use this calculator
Every field updates the result as you type — there is no submit step. The inputs below are pre-filled with a realistic example so you can see how the tool behaves before entering your own figures.
| Field | Unit | What it means |
|---|---|---|
| Remaining balance | $ | Enter a numeric value. |
| Interest rate | % | Enter a numeric value. |
| Months remaining | mo | Enter a numeric value. |
| Extra monthly payment | $ | Enter a numeric value. |
| One-time lump sum now | $ | Enter a numeric value. |
Worked example
Using the default values loaded into the calculator above, the result is:
| Input | Value |
|---|---|
| Remaining balance ($) | 250000 |
| Interest rate (%) | 6.5 |
| Months remaining (mo) | 300 |
| Extra monthly payment ($) | 300 |
| One-time lump sum now ($) | 0 |
| Output | Value |
|---|---|
| Interest saved | $85,737.48 |
| Current payment | $1,688.02 |
| New payment | $1,988.02 |
| Original payoff | 300 months |
| New payoff | 212 months |
| Original total interest | $256,405.37 |
| New total interest | $170,667.89 |
Reading the result
Financial projections compound small assumption changes into large differences over time. Rates, fees and tax treatment vary by lender and jurisdiction, so treat the output as a well-structured estimate for comparing options rather than a quotation.
Figures that change annually — tax bands, contribution limits, statutory rates — are exposed as editable inputs. Check them against current published values before relying on the result.
Sharing and saving a calculation
The "Copy link" button encodes every value you have entered into the page URL. Opening that link restores the calculation exactly, which makes it easy to bookmark a scenario, send it to someone else, or keep several variations side by side in separate tabs.
Frequently asked questions
What does the Mortgage Payoff Calculator do?
See what extra payments do to your payoff date and lifetime interest.
What result do the default values produce?
With the values pre-loaded in the calculator, interest saved comes to $85,737.48.
Is this calculator free to use?
Yes. It is free, requires no account, and runs entirely in your browser — nothing you enter is transmitted or stored on a server.
Can I save or share a calculation?
Yes. The "Copy link" button builds a URL containing all your entered values. Anyone opening that link sees the same calculation.
How accurate is the result?
The calculation itself is exact for the inputs given. Real-world accuracy depends on how well those inputs reflect your actual situation, so review the assumptions before relying on the figure.