EMI Calculator — Instalment, Interest Split and Prepayment

Quickly calculate your monthly loan installment, total interest, and full repayment amount. Whether you are planning a home loan, car loan, or personal loan, this free EMI calculator gives you a clear repayment picture before you commit.

Every EMI Is Two Payments Wearing One Number

An equated monthly instalment stays the same every month, which makes it easy to budget and easy to misunderstand. The total is fixed; what it consists of changes with every payment.

Each instalment covers the interest that accrued on the outstanding balance since the last one, and whatever is left over reduces the balance. Because the balance falls each month, the interest portion falls too, and the principal portion grows to fill the gap.

Interest this month = Outstanding balance × Monthly rate
Principal this month = EMI − Interest this month
New balance = Outstanding balance − Principal this month

Take a 500,000 loan at 12% a year over five years. The monthly rate is 1%, and the instalment works out at about 11,122.

The instalment never moves. The split shifts a little every month, and it accelerates: by the final year almost the whole payment is principal. Across the full sixty months this borrower pays about 667,000 in total, of which roughly 167,000 is interest.

The front-loading is mild over five years and severe over twenty-five, because the effect compounds with term. On a long mortgage the early years barely touch the balance at all — the mortgage calculator shows how extreme that becomes.

The Formula, and Why It Looks Like That

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

P is the amount borrowed, n is the number of monthly payments, and r is the monthly rate — the annual rate divided by twelve and by a hundred. A 12% annual rate is 0.01 as a monthly r, not 12 and not 0.12, and getting this conversion wrong is the most common reason a hand calculation disagrees with a lender's figure.

The shape of the equation follows from a single requirement: find the fixed payment whose present value, discounted at the loan rate, equals the amount borrowed. Everything else is algebra. It also explains why the relationship between rate and instalment is not proportional — doubling the rate does not double the payment, and the effect of a rate change grows with the term.

Term and Rate Pull in Different Directions

Borrowers usually optimise for the monthly figure, which is the wrong variable to fixate on if total cost matters. Lengthening the term lowers the instalment and raises the total substantially.

Moving from three years to seven cuts the monthly commitment by roughly half and nearly triples the interest. Neither choice is wrong — a lower instalment can be the difference between affordable and not — but it should be made knowing what the extra breathing room costs.

Prepayment: Why Timing Matters More Than Amount

A lump sum paid against a loan comes off the principal, which removes all the future interest that principal would have generated. Because interest accrues on the balance, the earlier the payment lands, the more interest it cancels.

The same 50,000 has a very different effect in year one than in year four of a five-year loan. Early, it removes four years of interest on that amount. Late, it removes months. This is why prepaying at the start of a loan is disproportionately effective and why doing it near the end achieves comparatively little.

Two things to check before prepaying:

• Whether a penalty applies. Some agreements charge a percentage of the amount prepaid, which can outweigh the interest saved on a loan already well advanced.
• Which variable the lender reduces. After a prepayment they can either shorten the term and keep the instalment, or keep the term and lower the instalment. The first saves markedly more interest; the second improves monthly cash flow. Lenders often default to one without asking, so state which you want.

Flat Rate and Reducing Balance Are Not Comparable

Two loans can advertise very different rates and cost almost the same, because they are quoted on different bases.

A reducing balance rate charges interest on what you still owe, which falls every month. This is what the EMI formula above assumes and what most mortgages and bank loans use.

A flat rate charges interest on the original amount for the whole term, regardless of how much you have repaid. On a 500,000 loan at 10% flat over five years, the interest is 250,000 — ten percent of the full amount, five times over — giving a total of 750,000 and an instalment of 12,500.

That headline 10% is not comparable to a 10% reducing-balance rate. To produce the same 12,500 instalment on a reducing-balance basis, the rate would need to be close to 17%. The flat quote sounds like a better deal and is considerably worse.

When comparing offers, ignore the advertised rate unless you know which basis it uses, and compare the instalment and the total repayable instead. Those two figures are directly comparable whatever the quoting convention. Our loan calculator sets out how to compare competing offers including fees.

What Happens If a Payment Is Missed

Missing an instalment has three separate consequences, and only the first is obvious.

There is usually a late fee, which is a fixed and generally modest cost. Interest continues accruing on the unreduced balance, so the loan quietly gets more expensive. And the missed payment is typically reported to credit reference agencies, which affects borrowing terms for years — normally the most expensive of the three by a wide margin.

Where a payment is going to be missed, contacting the lender before it happens is materially better than after. Restructuring, a payment holiday, or a term extension are all easier to arrange in advance, and an arrangement made ahead of time is usually recorded differently from a default.

EMI Questions