How to Calculate EMI: Formula and a Worked Example

Learning how to calculate EMI is one of the most useful money skills you can pick up before signing any loan agreement. EMI, or Equated Monthly Instalment, is the fixed amount you pay your lender every month until the loan is fully repaid. Each instalment covers part of the interest and part of the principal, so the amount stays the same even though the split between the two changes over time. Once you understand the formula, you can check any lender’s quote, compare loan offers, and choose a tenure that fits your monthly budget.

This guide explains the EMI formula term by term, walks through the calculation step by step, and finishes with a worked example you can follow with a simple calculator. To check your own loan in seconds, use our free Loan EMI Calculator.

The Formula

The standard EMI formula is:

EMI = P x r x (1 + r)^n / ((1 + r)^n – 1)

Each letter has a clear meaning. P is the principal, the amount you borrow. r is the monthly interest rate, worked out as the annual interest rate divided by 12 and then by 100. So a 10% annual rate gives a monthly rate of 0.10 / 12, which is 0.008333. n is the total number of monthly instalments, so a 5-year loan means 60 months. The (1 + r)^n part is what makes the formula work: it accounts for interest being charged on the reducing balance month after month, rather than on the full original amount.

Two things about this formula are worth noticing. First, the EMI depends on the monthly rate, not the annual rate, so using 10 instead of 0.008333 would give a wildly wrong answer. Second, the formula assumes a fixed interest rate and equal monthly payments for the whole tenure. If your rate is floating, the EMI is recalculated whenever the rate changes.

How to Calculate EMI Step by Step

1. Write down the three inputs: the loan amount (P), the annual interest rate, and the tenure in years.
2. Convert the annual rate to a monthly rate: divide the annual rate by 12, then by 100. For 10% a year, that is 10 / 12 / 100 = 0.008333.
3. Convert the tenure to months: multiply the years by 12. A 5-year loan is 60 monthly instalments.
4. Work out (1 + r)^n, the growth factor. With r = 0.008333 and n = 60, this is about 1.6453.
5. Multiply P by r and by the growth factor, then divide by the growth factor minus one. The result is your monthly EMI.

Keep the intermediate numbers unrounded while you work, and round only the final EMI to two decimal places. Rounding the monthly rate early is the most common reason a hand calculation drifts a few rupees away from the calculator’s answer.

Worked Example

Take a loan of Rs 5,00,000 at 10% interest per year for 5 years. First, convert the inputs: the monthly rate r is 10 / 12 / 100 = 0.008333, and the number of instalments n is 5 x 12 = 60. The growth factor (1 + r)^n is (1.008333)^60, which is about 1.6453.

Now apply the formula: EMI = 5,00,000 x 0.008333 x 1.6453 / (1.6453 – 1) = Rs 10,623.52 per month. Over 60 months you pay 10,623.52 x 60 = Rs 6,37,411 in total. Subtracting the principal gives total interest of Rs 1,37,411. So the loan costs Rs 1,37,411 more than the amount borrowed, spread evenly across five years of equal monthly payments.

It also helps to see how the first instalment splits. In month one, interest is charged on the full Rs 5,00,000, which is 5,00,000 x 0.008333 = Rs 4,167. The rest of the EMI, Rs 6,457, repays principal. By the final months the balance is much smaller, so almost the whole EMI goes toward principal. That shifting split is why early repayments cut total interest so effectively.

Common Mistakes / Good to Know

• Using the annual rate as the monthly rate: always divide by 12 and by 100 before putting r into the formula.
• Using years instead of months: n must be the number of monthly payments, so multiply years by 12.
• Forgetting extra charges: processing fees, insurance, and prepayment penalties sit outside the basic formula, so your bank’s final figure can differ slightly from the formula’s answer.
• Choosing the longest tenure by default: a longer tenure lowers the EMI but raises total interest a lot, so compare total payment, not just the monthly figure.

One more point worth remembering: the EMI formula is an estimate for a fixed-rate, reducing-balance loan. It is accurate for standard home, car, and personal loans, but always confirm the final schedule with your lender before signing.

Frequently Asked Questions

Once you know your EMI, the next step is seeing how each payment is split. Use our Repayment Schedule Calculator to view the month-by-month interest and principal breakdown for the same loan.

And if you want to see how a loan payment fits into your monthly budget, read How to Calculate In-Hand Salary from CTC: Formula and Example to work out what actually lands in your bank account each month.