How loan amortization works

Open an amortization schedule and you can see the loan unwind month by month: same EMI, shifting mix of interest and principal, balance ticking down to zero. Below is a full twelve-month example from the same math the EMI calculator uses, not a separate spreadsheet.

What each column means

For a reducing-balance loan the schedule typically shows:

• Month: payment number
• Payment: the installment applied that month (usually the fixed EMI; the last month may adjust for rounding)
• Principal: how much of that payment reduced the balance
• Interest: charge on the prior balance
• Prepayment: optional extra principal (zero in this example)
• Balance: what remains after the payment

If flat versus reducing methods are still fuzzy, read flat vs reducing-balance interest first. This schedule is reducing balance only.

Method

1. Compute the fixed EMI with the standard formula.
2. Each month: interest = balance × monthly rate; principal part = EMI − interest (with ordinary currency rounding); subtract principal (and any prepayment) from the balance.
3. Stop at the planned tenure (or earlier if prepayments clear the loan).
4. Total interest is the sum of interest rows; total payment is principal plus that interest.

Worked example

Principal ₹120,000, annual rate 10%, tenure 12 months, no prepayment. From the calculator:

• Monthly EMI = ₹10,549.91
• Total interest = ₹6,598.89
• Total payment = ₹126,598.89
• Schedule length = 12 months

First three months:

Month 1 interest is ₹1,000.00 because 120,000 × 10% ÷ 12 = 1,000. By month 3 interest has already fallen to ₹840.17 as the balance drops.

Last month:

Payment in month 12 is ₹10,549.88, two paise under the usual EMI, because the calculator clears the final rounding residual so the balance hits exactly zero. That last-row tweak is part of the same code path, not hand editing.

Notice the arc: early payments are interest-heavy relative to the later ones; by the end almost the entire installment is principal. Stretching tenure stretches that arc and usually raises total interest. See how loan tenure affects EMI and total interest. Adding a monthly prepayment shortens the schedule; that story is in how prepayment changes EMI and total interest.

Rounding and the last row

Currency is rounded to two decimals in the calculator. Over a year those pennies can leave a tiny residual, so the final payment may differ slightly from the steady EMI, as in month 12’s ₹10,549.88. That is cleanup, not a hidden rate change. When you audit a bank PDF, expect similar last-row adjustments; the important part is that the closing balance is zero and the summed interest matches the disclosed total.

Show the schedule in the tool

Enter the same inputs and expand the amortization table. The numbers should match the rows above. If you change the rate or tenure, rebuild your expectations from the new first interest line instead of copying this article’s figures.

Reading a lender’s schedule

Ask for the same columns. Check whether prepayments recalculate EMI or simply cut principal after a fixed installment (products differ). Match the opening balance, rate, and first interest line against your sanction letter before you trust a brochure total.

Bring three checks to any PDF schedule you receive:

1. Opening balance equals the amount you actually financed (after disbursement cuts, if any).
2. First interest matches balance × monthly rate under the stated annual rate.
3. Final balance is zero, and the sum of interest columns is close to the “total interest” headline.

If those three line up, you understand the shape of the loan even before you debate fees. If they do not, the schedule is incomplete or the product is not a simple reducing-balance EMI, and you should get a written explanation before you sign.