Search Ctrl K
Home / Tools
THE FEUTEX TOOLKIT

Mortgage Amortization and Extra Payments

Plan mortgage amortization and extra payments with transparent inputs, a detailed result and clearly stated assumptions.

Finance workspace● Runs in your browser
01 Your input
02 Your result
View or copy raw result data
Sources and model references

How to use this tool

  1. Enter your values, or load the example to see the input structure.
  2. Run the calculation and review its assumptions and detailed results.
  3. Copy or download the full result for your records.

Try this example

{
  "principal": 250000,
  "rate": 5,
  "months": 360,
  "extra": 100,
  "tax": 200,
  "insurance": 80
}

Accuracy and scope

Uses your supplied values. Estimates do not include unstated taxes, fees, policies or changing provider rules. Financial projections assume fixed rates and are scenarios, not forecasts or personalized advice. Mortgage schedule uses a fixed nominal rate divided by 12; no prepayment penalties or variable rates.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.