How to Calculate EMI Manually

An Equated Monthly Instalment is a single fixed payment covering both interest and principal, sized so that the last instalment clears the loan exactly. Most people never calculate one by hand, but knowing how is useful for one specific reason: it lets you check whether the figure a lender has quoted is reasonable.

The formula

Every EMI comes from the same equation:

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

• P is the principal, the amount actually borrowed
• r is the monthly interest rate, not the annual one
• n is the tenure in months, not years

The two conversions in that list are where nearly every manual calculation goes wrong. An annual rate of 9% is not 9 in the formula, and a 15-year loan is not 15.

Converting the rate

Divide the annual percentage by 12, then by 100. A 9% annual rate becomes 0.09 ÷ 12 = 0.0075 per month. A 8.5% rate becomes 0.00708333.

A worked example

Take a home loan of ₹25,00,000 at 9% annual interest over 15 years.

1. P = 25,00,000
2. r = 0.09 ÷ 12 = 0.0075
3. n = 15 × 12 = 180
4. (1 + 0.0075)¹⁸⁰ = 3.83804
5. Numerator: 25,00,000 × 0.0075 × 3.83804 = 71,963
6. Denominator: 3.83804 − 1 = 2.83804
7. EMI = 71,963 ÷ 2.83804 = ₹25,357

Over 180 months that is ₹45,64,200 repaid against ₹25,00,000 borrowed — ₹20,64,200 of interest, or 45% of everything you hand over.

The awkward step

Step 4 is the part you cannot do in your head. Raising 1.0075 to the power of 180 needs a scientific calculator, a spreadsheet, or theEMI calculator on this site. In a spreadsheet the whole thing is one function:=PMT(0.09/12, 180, -2500000).

Why early instalments are mostly interest

The instalment never changes, but what it is made of changes every month. Interest is charged on the balance still outstanding, which is highest at the start.

In the first month of the loan above, interest is 25,00,000 × 0.0075 = ₹18,750. Of a ₹25,357 payment, only ₹6,607 reduces the debt. By the final year the position has reversed almost entirely.

Figures rounded. The crossover — the month where more of your payment goes to principal than to interest — falls around year seven on this loan, and around year eleven on a 20-year one.

Why this matters for prepayment

Because interest accrues on the outstanding balance, money paid in early removes principal that would otherwise have attracted interest for the entire remaining term. The same amount paid in the final years saves almost nothing, because there is little term left for interest to accumulate over.

Most Indian lenders apply a prepayment by shortening the tenure rather than reducing the EMI, which is usually the better outcome. It is worth confirming which your lender does, because it is often not automatic and the difference over a full term is substantial.

Checking your lender's figure

Your calculated EMI should land within a few rupees of the lender's. If the gap is larger, the usual explanations are:

• Processing fees rolled into the loan. A 1% fee on ₹25,00,000 adds ₹25,000 to the principal before interest is applied.
• Insurance bundled with the loan. Often financed alongside it and rarely mentioned in the headline rate.
• Daily rather than monthly rest. Some lenders compute interest daily, which shifts the figure slightly.
• A different rate from the advertised one. Advertised rates are usually the best available to the strongest applicants.

A difference of a few hundred rupees a month is worth asking about. Over 180 instalments, ₹300 a month is ₹54,000.

Try it

The EMI calculator does this as you type, with a year-by-year breakdown showing exactly where the crossover falls for your loan. Everything runs in your browser, so your figures never leave your device.

This page explains the arithmetic. It is not financial advice and cannot tell you whether a loan is right for you — see ourdisclaimer.