Mortgage Interest Calculator : Lifetime Cost of Home Loan Interest

Discover how much of your total mortgage payments go toward interest rather than equity. Compare 15-year vs 30-year terms to see dramatic interest savings.

Interactive Calculator

100% Client-Side Engine

Total Lifetime Mortgage Interest

$347,514.57

Interest represents 115.84% of the financed loan amount.

Financed Mortgage Balance

$300,000

Monthly P&I Payment

$1,798.65

Total Home Loan Repayment

$647,514.57

Step-by-Step Examples

$300,000 Mortgage at 6% for 30 Years

Lifetime mortgage interest calculation.

Inputs: Loan Amount: $300,000, Rate: 6%, Term: 30 Years

Result: Total Interest: $347,514.57, Monthly P&I: $1,798.65

Lifetime interest ($347.5k) exceeds the original $300k mortgage principal.

How to Use This Tool

Enter home value and down payment.
Enter mortgage interest rate (APR).
Specify mortgage loan term in years.
Review total lifetime interest paid and percentage of loan balance.

Frequently Asked Questions

A 15-year mortgage typically saves 50% to 65% of total lifetime interest because the principal is paid down twice as fast.

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