How is your loan EMI actually calculated?
Every home, car or personal loan you take is priced by the same one-line formula. Once you can read it, lenders hold far fewer surprises.
The one formula behind every EMI
An Equated Monthly Instalment (EMI) is a fixed payment that clears both interest and principal over a set number of months. It is calculated as:
EMI = P × r × (1 + r)n ÷ ((1 + r)n − 1)
- P — the principal (amount you borrow)
- r — the monthly interest rate, i.e. the annual rate ÷ 12 ÷ 100
- n — the number of monthly instalments (years × 12)
Notice that the rate is converted to a monthly figure. A 9% annual rate is 0.75% per month, or 0.0075 as a decimal — that small number is what gets compounded over every instalment.
Why your first EMIs are almost all interest
The EMI itself stays constant, but its split between interest and principal does not. Interest each month is charged on the outstanding balance, which is highest at the start. So in the early years most of your payment services interest and only a sliver reduces the loan. This gradual shift is called amortization.
This is why two identical-looking loans can cost wildly different amounts of total interest: the longer the tenure, the longer that high-interest early phase lasts.
A worked example
Borrow ₹10,00,000 at 9% for 20 years and the EMI is about ₹8,997. Over 240 months you repay roughly ₹21.6 lakh — meaning you pay about ₹11.6 lakh in interest, more than the original loan. Cut the tenure to 10 years and the EMI rises to about ₹12,668, but total interest drops to roughly ₹5.2 lakh.
What moves your EMI the most
- Tenure has the biggest effect on total interest: a longer tenure lowers the monthly outgo but balloons the lifetime cost.
- Interest rate moves both the EMI and the total cost — even a 0.5% difference is worth lakhs on a long home loan.
- Principal scales everything linearly: borrow 10% less and your EMI falls by 10%.
Use it before you sign
Before accepting any loan, plug the exact principal, rate and tenure into a calculator and look at two numbers: the EMI you will live with each month, and the total interest you will pay over the life of the loan. The second number is the one lenders rarely highlight.
Try it with your own numbers
Put this into practice with the QuickyLoan EMI Calculator.
Open the EMI Calculator →More guides
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