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MasterMath

Amortization Schedule Calculator

On 150,000 at 4% over 30 years the payment is 716.12, and you repay 257,804 in total. The first payment is 500 interest; the last is 2.38. See the full schedule year by year.

Currency and number format for

Monthly payment

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Monthly payment—
Total interest—
You will repay in total—
Number of payments—
Interest in the first payment—
Interest in the last—

How this was worked out

    The formula

    payment = principal × i ÷ (1 − (1 + i)^−n)

    Where it comes from

    An amortization schedule shows where every payment goes. The payment itself never changes, but its make-up does: interest is charged on whatever is still owed, so it starts high and falls as the balance drops, and the principal portion grows to fill the gap.

    How to work it out by hand

    1. Work out the fixed payment from the amortisation formula
    2. For each month, interest is the outstanding balance times the monthly rate
    3. The rest of the payment reduces the balance
    4. Repeat with the new balance until it reaches zero

    What is worth knowing

    The schedule is what makes the real cost visible: on this loan you pay 107,804 in interest, which is 72% of what you borrowed. It also shows why the timing of overpayments matters so much. An extra 100 in month one removes interest that would have accrued for 359 more months; the same 100 in the final year removes almost nothing. Halfway through a 30-year term you will still owe around 63% of the original balance, which surprises most people — the curve is far flatter at the start than intuition suggests.

    Frequently asked questions

    Why is so much of the early payment interest?

    Interest is charged on what you still owe, and at the start that is nearly the whole loan. The payment is fixed, so whatever is left after interest goes to principal — and at first that is very little.

    When is the best time to overpay?

    As early as you can. An overpayment removes all the future interest that balance would have generated, so the earlier it lands the more it saves.

    How much will I still owe halfway through?

    On a 30-year loan at typical rates, roughly 60 to 65% of the original amount. The balance falls slowly at first and quickly at the end.

    Does this include taxes, insurance or fees?

    No. It shows the interest on the amount borrowed. Property taxes, insurance and arrangement fees are real costs on top of this.