Read the four numbers in each row
An amortization table follows the balance from one payment to the next. The opening balance is the amount owed before the payment. Interest is the charge for the period. Principal is the amount of the payment that reduces the debt. The closing balance becomes the next row’s opening balance. [1]
For a standard monthly model:
Interest = opening balance × annual interest rate ÷ 12
Principal repaid = payment − interest
Closing balance = opening balance − principal repaid
The lender is not arbitrarily deciding to “take all the interest first.” The early interest share is larger because the outstanding balance is larger. That distinction matters when evaluating an extra payment or a refinance.
A first-payment example
Assume a $200,000 fixed-rate loan, a 6% annual interest rate, and a 30-year repayment term. Its principal-and-interest payment is approximately $1,199.10.
| First payment component | Calculation | Amount |
|---|---|---|
| Interest | $200,000 × 0.06 ÷ 12 | $1,000.00 |
| Principal | $1,199.10 − $1,000.00 | $199.10 |
| Remaining balance | $200,000 − $199.10 | $199,800.90 |
In the second month, interest is calculated on about $199,800.90 rather than $200,000. The scheduled payment is unchanged, but slightly more reaches principal. The shift accelerates over time as the balance falls.
The table uses cents for readability. A lender’s posting rules, exact payment dates, and rounding can create small differences from an educational model.
Why an extra principal payment helps
Suppose an additional $100 is applied to principal with the first payment. The balance is $100 lower than it otherwise would have been. At 6% with monthly interest, that alone reduces the following month’s modeled interest by $0.50. Keeping the scheduled payment the same then repays a little more principal.
The benefit continues while that balance difference exists. It is not a one-time rebate, and it is not automatically the same as reducing the required payment. A recast, when offered, is a separate process that can change the payment after a substantial principal reduction.
Check for prepayment restrictions and confirm the servicer’s instructions. Keep an emergency reserve rather than putting every available dollar into equity that may be difficult to access later.
What a basic schedule leaves out
A principal-and-interest schedule does not normally include escrow deposits, property taxes, homeowners insurance, late charges, or mortgage insurance. An escrow adjustment may change the amount due even when the note rate and principal-and-interest payment stay fixed.
Daily-interest loans can differ from the monthly formula because payment timing changes the number of accrued days. Variable-rate loans require a new projection when the rate or payment changes. Interest-only and balloon loans do not follow a standard fully amortizing schedule throughout their lives.
Negative amortization means the unpaid balance grows because a payment does not cover accrued interest or because amounts are added to principal. Do not interpret a low initial payment as proof that a loan is being paid down.
Use the schedule to make a decision
Compare at least three columns when considering a change: cumulative interest, remaining balance, and total cash paid. A lower monthly payment after refinancing can coexist with more future interest if the term is extended.
For an extra-payment plan, run a baseline schedule and an identical schedule with only the extra principal changed. Keep the rate, starting date, and fees constant so that the difference actually measures the strategy. A shorter payoff estimate is useful only when the added payment fits the budget.
Before a final payoff, request an official payoff statement. The current statement balance may exclude interest accruing through the actual payoff date and other permitted charges.
Frequently asked questions
Why is so little principal paid at the beginning?
Interest is calculated on the outstanding balance, which is largest at the beginning. With a level payment, the remainder available for principal starts smaller and grows as the balance falls.
Does paying twice a month automatically save interest?
Not necessarily. Savings depend on how payments are applied and whether you pay extra over the year. Splitting one monthly payment into two parts is different from making 26 half-payments annually.
Is an amortization schedule a payoff quote?
No. It is a projection under stated assumptions. Obtain the lender’s payoff quote for the exact amount required on a particular date.
Sources & calculation notes
Primary references are linked below. Dates, limits, and product terms can change; confirm the applicable details before acting.
Use this guide thoughtfully. Educational information, not individualized financial, investment, tax, or legal advice. Examples are hypothetical unless a source is explicitly identified. Verify current terms and consider qualified professional guidance for your situation.