Amortization, a Worked Example

An amortization schedule is just the full month-by-month record of how a loan's fixed payment splits between interest and principal, from the very first payment to the very last. The last lesson showed the two ends of that story — now here's what the middle actually looks like.

Take that same $200,000 loan at a fixed 6% rate over 30 years. The payment stays at roughly $1,199.10 every month without exception, but look at how differently that same $1,199.10 gets divided depending on where the loan is in its life.

Loan: $200,000 | Rate: 6% fixed | Term: 30 years | Payment: $1,199.10/mo (constant)

Payment #1    (balance: $200,000.00) → Interest $1,000.00 | Principal $199.10
Payment #181  (balance: $142,097.98) → Interest   $710.49 | Principal $488.61
Payment #349  (balance:  $13,933.23) → Interest    $69.67 | Principal $1,129.43

The monthly payment never changes — only the mix inside it does.

On a fixed-rate mortgage, the total monthly payment stays constant, but the split between interest and ____ shifts throughout the loan.

By payment #181, roughly 15 years in, the balance has only dropped from $200,000 to about $142,098 — less than a third of the original loan, even though half the term is gone. That's the front-loaded nature of interest: it takes the biggest bite early, when the remaining balance is largest, so principal barely dents the total for a long stretch.

Why does the interest portion of a fixed mortgage payment shrink so much by the later years of the loan?

In a typical fixed-rate amortization schedule, the earliest payments are weighted more heavily toward interest than the final payments are.