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Debt & Loans

Principal

The original sum of money borrowed in a loan or invested in an account, before interest, fees, or returns are added.

Principal

In finance, principal refers to the original amount of money borrowed in a loan or placed in an investment, before interest, returns, or fees are added or subtracted.

Principal in Loans

When you take out a loan, the principal is the amount you initially borrowed. Your loan payments are split between:

  • Principal: Reduces your outstanding balance
  • Interest: Paid to the lender for the use of their money

Early in an amortizing loan (like a mortgage), most of each payment goes to interest. As the principal balance decreases, interest costs decline and more of each payment reduces the principal.

Example:

  • Mortgage amount: $350,000 → this is the principal
  • Monthly payment: $2,200
  • Month 1: $1,750 interest, $450 principal reduction
  • Month 180 (year 15): $1,100 interest, $1,100 principal reduction

Principal in Investments

In investing, the principal is the initial amount invested — before any returns, dividends, or gains.

  • You invest $10,000 → principal is $10,000
  • After one year at 7% → total is $10,700; principal is still $10,000; $700 is interest/return

The distinction matters because:

  • Return of principal = getting your original investment back (not a gain, not taxed as income)
  • Return on principal = the profit generated by the investment (taxable as capital gains or income)

Principal Balance

The principal balance on a loan is the current outstanding amount owed, not including any accrued interest. It decreases with each principal payment made.

Interest-only loans do not reduce principal — monthly payments cover only interest, leaving the principal balance unchanged until the loan is paid off in a lump sum (balloon payment) or refinanced.

How to Pay Down Principal Faster

For amortizing loans, any additional payment above the required monthly payment goes directly toward principal (if specified). This:

  • Reduces future interest accrual (since interest is calculated on the remaining principal)
  • Shortens the loan term
  • Reduces total interest paid

On a $300,000 mortgage at 6.5% for 30 years, paying an extra $200/month saves over $90,000 in interest and pays off the loan 5+ years early.

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