See exactly how mortgage payments evolve and where lifetime interest is concentrated.
Overview
Mortgage amortization makes clear why early refinancing and prepayment decisions matter.
The schedule shows period-by-period principal and interest allocation.
Most long mortgages pay interest heavily in initial years.
Understanding this timeline helps optimize payoff strategy.
Steps
Input financed principal balance.
Set APR and total years.
Review monthly payment breakdown.
Check balance at years 5, 10, and 15.
Compare accelerated payoff schedules.
Math
Interest_t = Balance_(t-1) × r; Principal_t = Payment - Interest_t
Interest is computed on current balance each period; remainder of payment reduces principal.
Worked cases
Generate months 1-12 amortization rows.
Interest dominates early payments in long-term mortgages.
Read balance and cumulative interest at period 120.
Useful for refinance and equity planning decisions.
Apply additional principal each month.
Schedule shortens and cumulative interest drops significantly.
Why use this
Questions