EMIs – understanding the math

EMIs are a big part of our home purchase decision. We explain how a percentage of your monthly income pays the home loan. 

If you are about to take a home loan, you are justifiably worried about the ‘EMI’ you have to pay the bank every month. The higher the EMI, the higher is the deduction from your monthly income till the loan is completely repaid. The EMI computation can also get slightly tricky, so it is best to understand how your bank calculates the numbers.

The EMI (Equated Monthly Instalment) is an amount of money calculated by the lending institution after taking certain factors into account. These factors include, and are a combination of, the principal amount (P), interest payable (I), and total number of instalments (N). The loan tenure is calculated on the basis of the number of years chosen but in terms of the number of months.

Do note the formula that your bank uses to compute the EMI:

[P x I x (1 + I) x N] ÷ (1 + I) x (N-1)

Now suppose you seek a home loan of Rs 40 lakh (P) at an interest rate of 12% (I) for a tenure of 10 years, i.e. 120 months (N). You may use the formula above to arrive at the EMI calculation. Or if you don’t want to be bogged down by the mathematics of it all, simply use your bank’s online home loan EMI calculator to arrive at the estimated EMI payable per month.

Points to note about the EMI calculations:

1. The EMI does not comprise equal parts principal amount and interest. In the initial years of the loan, the interest component is higher. It gets correspondingly lower as the loan progresses, while the principal amount is higher.
2. Thus, you cannot think that half of your loan is repaid after 5 years out of a total tenure of 10 years.
3. The EMI structure is liable to change during the repayment tenure, for three reasons:

• You may opt for a floating rate of interest, which can reset the interest periodically.
• You choose to pay differential or staggered EMIs, i.e. lower amounts for a few years and then larger EMIs later. This option is offered only by a few financial institutions in India.
• You repay incremental amounts in addition to the regular EMIs. The prepayment amounts reduce the principal amount of the loan and the interest is recalculated on the balance amount.

Premier banks and housing finance institutions offer an online home loan calculator that makes the EMI calculations easy. All you have to do is fill in the numbers as prompted for a close estimate of the EMI you will pay for your home loan.