How much of my personal loan payment goes to principal vs interest?

How amortization works: Personal loans use fully amortizing schedules. Each monthly payment is the same dollar amount, but the split between principal and interest changes every month. Early on, outstanding principal is high so more interest accrues. As principal declines, less interest accrues per month, freeing more of the fixed payment for principal reduction.

Example: $15,000 loan at 12% APR over 48 months = $395/month payment. Month 1: $150 interest, $245 principal. Month 12: $133 interest, $262 principal. Month 24: $108 interest, $287 principal. Month 36: $79 interest, $316 principal. Month 48: $4 interest, $391 principal.

Why this matters for prepayment: Extra principal payments early in the loan life save the most interest, because you reduce the balance accruing interest for the remaining months. Making an extra $500 payment in month 3 saves more total interest than the same payment in month 30.

How to see your amortization schedule: Most lenders provide a full amortization table in your loan documents or online account. A standard amortization calculator also generates this with your loan amount, rate, and term.

Total interest cost perspective: On the $15,000 at 12% over 48 months, total interest paid is approximately $1,960. This is the real cost of the loan and illustrates why a lower rate or shorter term dramatically reduces total cost.