The principal is the underlying amount you actually borrow. Every interest charge, every monthly payment, and every payoff figure is calculated from the principal balance — which shrinks as you pay the loan down.
Original vs remaining principal
Original principal is the loan amount on day one. Remaining principal is what you still owe at any given moment. Interest each period is charged on the remaining principal, which is why amortization is front-loaded with interest.
Paying down principal faster
Any payment beyond the scheduled minimum, if applied to principal, removes that dollar from future interest calculations. A $1,000 extra payment in year 1 of a 5-year, 12% APR loan saves roughly $300 in lifetime interest.
Frequently asked questions
Is my monthly payment all principal?
No. Each scheduled payment is split between interest (charged on the remaining principal) and principal. The split shifts toward principal over time.