Flat vs Reducing Balance Interest Rate: Which Loan Costs More?
A 10% flat rate costs far more than 10% reducing. See why, with a worked ₹5 lakh example, how to convert a flat rate to its real rate, and what to ask lenders.
The short answer
A flat rate charges interest on the full loan amount for the whole tenure, even after you have repaid part of it. A reducing balance rate charges interest only on the amount you still owe each month. That is why the same number is not the same cost: a ₹5,00,000 loan for 3 years costs ₹1,50,000 in interest at a 10% flat rate, but about ₹80,809 at 10% reducing. To compare offers fairly, convert any flat rate to its reducing equivalent and check it in the EMI Calculator, which uses the reducing balance method.
How each method works
Flat rate
The lender works out interest once, on the original principal, and spreads it evenly:
The interest part of every EMI stays the same from the first month to the last, even though the amount you owe keeps falling.
Reducing balance rate
Each month, interest is charged only on the outstanding balance:
The EMI itself stays fixed, but the split changes: early EMIs are mostly interest, later EMIs are mostly principal. Home loans and most bank loans in India are quoted this way. Flat rates tend to appear on some consumer durable, vehicle and small personal loans, which is exactly where the difference catches people out.
Worked example: ₹5 lakh for 3 years at "10%"
| Item | 10% flat | 10% reducing |
|---|---|---|
| Interest formula | 5,00,000 × 10% × 3 | Charged on the falling balance |
| Total interest | ₹1,50,000 | ₹80,809.24 |
| Total repaid | ₹6,50,000 | ₹5,80,809.24 |
| EMI (36 months) | ₹18,055.56 | ₹16,133.59 |
The flat-rate loan costs ₹69,190.76 more, and its EMI is about ₹1,922 higher every month. The reducing figures are what the EMI Calculator shows for ₹5,00,000, 10% and 36 months.
Look at month one of the reducing loan: interest is 5,00,000 × 10% ÷ 12 = ₹4,166.67, so ₹11,966.93 of the first EMI goes to principal. After 12 EMIs you owe about ₹3,49,629. On the flat loan, the lender still charges interest as if you owed the full ₹5,00,000 in month 36.
How to convert a flat rate to its real (reducing) rate
There is no simple multiply-by formula that is exact, but you can find the equivalent rate in a minute with the calculator:
For the example, 17.92% reducing gives an EMI of ₹18,056.14, almost exactly the flat-rate EMI. So a "10% flat" loan over 3 years really costs about 17.9% a year on a reducing basis.
A second example: ₹3,00,000 for 5 years at 8% flat. Interest is ₹1,20,000 and the EMI is ₹7,000. Entering 14.13% for 60 months gives ₹7,000.71, so 8% flat is roughly 14.1% reducing. The same ₹3,00,000 at a true 8% reducing rate would have an EMI of ₹6,082.92.
The gap grows with tenure, which is why a low-looking flat rate on a long loan can be the most expensive offer on the table.
Rough rule of thumb (and why not to rely on it)
You will often see "the reducing rate is about 1.8 to 1.9 times the flat rate". The two examples above give 1.79 and 1.77 times, so the idea is in the right range, but the exact ratio depends on the tenure and the rate. Use it only to spot a suspicious offer, then check with the calculator.
What to ask a lender before you sign
- "Is this a flat rate or a reducing balance rate?" Ask in writing if the advertisement just says "10% interest".
- "What is the APR?" In India, the RBI's circular of 15 April 2024 requires banks, NBFCs and other regulated lenders to give a Key Facts Statement (KFS) for retail and MSME term loans sanctioned from 1 October 2024. The KFS must show the Annual Percentage Rate, which includes the interest rate and the other charges linked to the loan, along with the repayment schedule.
- "What is the EMI and total amount payable?" Compare these numbers between offers rather than the headline rate.
- "Are there processing fees or insurance added to the loan?" These raise the real cost even when the rate looks the same.
Common mistakes
- Comparing a flat rate with a reducing rate directly. A 12% flat car loan is not cheaper than a 15% reducing personal loan just because 12 is smaller. Convert first.
- Calculating flat-rate loans in a reducing-balance calculator. If you enter "10%" for a flat-rate loan in an EMI calculator, you will see a lower EMI than the lender will actually charge.
- Ignoring the tenure. The longer the loan, the further apart the flat and reducing costs become.
- Forgetting prepayment. On a reducing balance loan, prepaying cuts the balance and future interest. On a flat-rate loan the interest was fixed at the start, so check the lender's foreclosure terms before assuming you will save much.
Checking the amortisation schedule
The EMI Calculator can show the month-by-month schedule for a reducing balance loan: the EMI, the interest and principal parts, and the balance after each payment. Use it to see how much principal you will have repaid by a certain month, for example before deciding whether to prepay or switch lenders. For more on how EMIs are calculated, read the EMI Calculator Guide.
This guide explains the general rules and is not tax advice.
Frequently asked questions
Is a flat interest rate better than a reducing rate?
No, for the same number a flat rate costs more. A ₹5,00,000 loan for 3 years costs ₹1,50,000 interest at 10% flat but about ₹80,809 at 10% reducing.
How do I convert a flat rate to a reducing rate?
Work out the flat-rate EMI, then find the rate that gives the same EMI in a reducing balance EMI calculator. A 10% flat rate over 3 years equals about 17.9% reducing.
Which interest method do Indian home loans use?
Home loans and most bank loans are quoted on a reducing balance basis, where interest is charged only on the outstanding amount each month.
What is APR on a loan?
The Annual Percentage Rate is the yearly cost of the loan including interest and other charges. RBI rules require lenders to show it in the Key Facts Statement for retail and MSME term loans.
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