Principal vs. Interest: Where Your Payment Actually Goes

Every mortgage payment is split into two parts: principal (reducing what you actually owe) and interest (the cost of borrowing). Early in your amortization, a larger share of each payment goes to interest, because interest is calculated on your outstanding balance — which is largest at the very start.

As you pay down the balance, less of each payment is consumed by interest and more goes toward principal — the split gradually shifts over the life of the mortgage, even though your total payment stays the same (on a fixed-rate mortgage).

This is why extra payments early in your mortgage have an outsized impact: they reduce the balance that a disproportionate amount of interest is being charged against, at the point in the mortgage where that balance — and the interest on it — is at its highest.

Our mortgage payment comparison and prepayment calculators both show this split visually, so you can see exactly how much of a given payment is actually reducing what you owe versus covering the cost of borrowing.