How EMI works — and why early EMIs are mostly interest
Watch a loan’s EMI split between interest and principal month by month, and see why tenure and early prepayments matter so much.
An EMI (equated monthly instalment) is the same amount every month. Inside it, though, two things happen: you pay interest on what you still owe, and whatever’s left reduces the loan. That split changes every single month.
Month one vs the last month
On a ₹50 lakh loan at 8.5%, the EMI is ₹43,391.
- Month 1: interest is ₹50,00,000 × 8.5% ÷ 12 = ₹35,417. Only ₹7,974 goes to the loan.
- Month 240: almost nothing is left to charge interest on, so nearly the whole EMI is principal.
Over the first year, about ₹4.2 lakh of your ₹5.2 lakh in EMIs is interest. Principal only overtakes interest in year 13 of a 20-year loan.
The formula (if you like that sort of thing)
EMI = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
- P is the loan amount
- r is the monthly rate (annual rate ÷ 12)
- n is the number of months
Every month: interest = balance × r, and principal = EMI − interest. The balance falls a little faster each month, so interest shrinks and principal grows. That’s why the curve bends.
Tenure is the biggest lever
Same ₹50 lakh at 8.5%:
| Tenure | EMI | Total interest |
|---|---|---|
| 15 years | ₹49,237 | ₹38.6 lakh |
| 20 years | ₹43,391 | ₹54.1 lakh |
| 25 years | ₹40,261 | ₹70.8 lakh |
| 30 years | ₹38,446 | ₹88.4 lakh |
Stretching from 20 to 30 years lowers the EMI by just ₹4,945 a month but adds ₹34 lakh in interest. Pick the shortest tenure whose EMI you can carry comfortably.
When rates change
Most home loans float with the RBI repo rate. A 0.5% change on our loan moves the EMI by roughly ₹1,600 a month (₹41,822 at 8%, ₹44,986 at 9%). When rates rise, banks usually keep your EMI and stretch the tenure, which is easy to miss and expensive. Check your loan statement after every rate change. RBI rules say your lender must tell you, and let you choose a higher EMI, a longer tenure or a switch to a fixed rate, so ask for the EMI to go up if you can afford it.
What this means for you
Because early EMIs are mostly interest, extra money paid early has the biggest effect. Every rupee you prepay in the first few years removes interest you’d otherwise pay for a decade or more. The prepayment calculator shows the saving, and the prepay or invest guide helps you decide if that’s the best use of the money.