How Loan EMI Is Calculated (and How Prepayments Save Interest)

Home loans, car loans and personal loans are usually repaid in equal monthly instalments, the EMI. The amount looks simple, but how it's made up changes month by month. Understanding it helps you compare offers, plan prepayments, and see how much the loan really costs.

The EMI formula

For a loan amount P, a monthly interest rate r (annual rate ÷ 12 ÷ 100) and n monthly payments:

EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)

Example: ₹10,00,000 at 9% a year for 5 years (60 months):

• r = 9 ÷ 12 ÷ 100 = 0.0075
• EMI ≈ ₹20,758
• Total paid ≈ ₹12,45,500, so total interest ≈ ₹2,45,500.

The Loan Calculator does this for you, with the total interest and a full amortization schedule you can download as CSV.

Why early EMIs are mostly interest

Each month, interest is charged on the outstanding balance. At the start, the balance is highest, so most of the EMI goes to interest and little reduces the principal. As the balance falls, the interest part shrinks and the principal part grows, while the EMI stays the same.

The amortization schedule shows this month by month: payment, interest, principal and remaining balance.

The effect of tenure

A longer tenure lowers the EMI but raises the total interest, often dramatically. Compare the same loan over different tenures in the calculator: the difference in total interest is usually the most eye-opening number.

Extra payments (prepayments)

Paying extra reduces the outstanding balance directly, so every later month has less interest. Prepayments early in the loan save the most. The Loan Calculator lets you add extra payments and shows how much sooner the loan ends and how much interest you save.

Before prepaying, check:

• Prepayment charges in your loan agreement (rules depend on the loan type and lender).
• Whether the lender reduces the tenure or the EMI after a prepayment. Reducing tenure usually saves more interest.
• Your emergency fund: don't use money you might need soon.

What the calculator doesn't include

The calculation covers principal and interest. Processing fees, insurance, taxes and other charges your lender adds come on top. Some lenders compound interest daily or round differently, so their figures can differ slightly. For floating-rate loans, the EMI or tenure changes when the rate changes.

Compare loan offers properly

• Compare the total cost (interest plus fees), not only the EMI.
• Check whether the rate is fixed or floating.
• Look at the effective annual rate when fees are significant.

Savings vs prepayment

If you're deciding between prepaying a loan and saving, the Compound Interest Calculator shows how savings would grow at a given rate. Comparing the loan's interest rate with what your savings earn after tax is a useful starting point. This is general information, not personal financial advice; for decisions about your own finances, consult a qualified adviser.

Common questions

Why does my bank's EMI differ slightly? Different rounding or day-count methods, or the first EMI covering a partial month.

Is my data stored? No. The calculation happens in your browser, and your loan details never leave your device.

Summary

• EMI depends on amount, rate and number of months.
• Early EMIs are mostly interest.
• Prepay early, prefer reducing tenure, and check charges.