Skip to main content
Financial Planning

Extra Payment Savings Calculator

Calculate how much interest and time you save by adding a fixed extra principal payment every month.

Your inputs

Results

Interest saved

$86,231.98

Months saved
93
New payoff time (months)
267
Regular payment
$1,498.88
Interest without extra payments
$289,593.37
Interest with extra payments
$203,361.39

✓Exact calculation — rounded only for display

Inputs are never added to links for financial, salary or health calculators.

What this calculator does

Adding a little extra to every payment goes straight to principal, which reduces the interest charged in every following month. Over a long mortgage the savings can be very large.

Formula and method

Each month: interest = balance × i; principal = payment − interest + extra. The loan is simulated with and without the extra amount, and the totals are compared.

Worked example

Calculated by this tool with its default inputs:

Inputs

  • Loan amount: 250000 (any currency)
  • Interest rate (annual): 6 %
  • Term: 30 years
  • Extra principal each month: 200 (any currency)

Results

  • Interest saved: 86,231.98
  • Months saved: 93
  • New payoff time (months): 267
  • Regular payment: 1,498.88
  • Interest without extra payments: 289,593.37
  • Interest with extra payments: 203,361.39

How to read the results

Months saved shows how much sooner you will be debt-free; interest saved is the guaranteed return on the extra payments.

Assumptions and limitations

  • Make sure your lender applies extra payments to principal, not to future payments.
  • Interest is rounded to the cent each month.

Financial results are estimates based on the inputs and assumptions shown. They are not financial advice; confirm figures with your lender, provider or a qualified adviser before making decisions.

Questions

Is monthly extra better than an annual lump sum?

For the same yearly amount, monthly extra payments save slightly more because they reduce the balance sooner. The Mortgage Prepayment Comparison Calculator shows the difference.

Methodology and verification

Result type
Exact mathematical calculation (rounded only for display)
Formula version
1.0
Automated verification
3 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
Editorial review
Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.

Privacy

Everything you enter is calculated in this browser and is not sent to Numerith or anyone else. Because this calculator can involve personal financial or health details, your inputs are never added to share links or saved to history. Privacy policy