Flat Rate vs Reducing Rate: Why 6% Costs 10.85%
A dealer says "only 6% interest" on a ₹8 lakh car loan, 5 years. It sounds cheaper than most bank loans. Then you work out the real rate and it's 10.85%. Nothing illegal happened. The dealer just used a different way of counting, and most people never learn it exists until they've signed.
If you only read one bit
- A flat rate of 6% on 5 years works out to about 10.85% on a normal reducing-balance loan.
- Over 5 years, the real rate comes out at roughly 1.8 times the flat rate you were told.
- On ₹8 lakh, flat 6% costs ₹2,40,000 in interest. A genuine 6% reducing loan would cost about ₹1,27,974.
- Across common flat rates and tenures, the real rate lands at roughly 1.75 to 1.85 times the flat rate.
Two ways of charging interest
With a reducing-balance loan, interest each month is worked out on what you still owe. As you pay the loan down, the interest falls. That's how banks usually price home, car and personal loans.
With a flat-rate loan, interest is worked out once, on the full original amount, for the whole period. Then the total is divided into equal monthly payments. Even when you've repaid most of the loan, you're still being charged as if you owed the whole thing.
Both can be quoted as "6% a year". They are not the same price.
The dealer example, worked out
You're offered ₹8,00,000 over 5 years at a flat 6%.
- Interest: 8,00,000 × 6% × 5 years = ₹2,40,000.
- Total to repay: 8,00,000 + 2,40,000 = ₹10,40,000.
- EMI: 10,40,000 ÷ 60 = ₹17,333 a month.
Now ask a different question: what yearly rate on a normal reducing-balance loan gives an EMI of ₹17,333 on ₹8 lakh over 60 months? Solving for that gives 10.85%. You were quoted 6%, and you're actually paying nearly double. A true 6% reducing loan on the same amount would have an EMI of about ₹15,466 and cost ₹1,27,974 in interest, which is ₹1,12,026 less.
How much higher is the real rate?
Keep the tenure at 5 years and change the flat rate:
| Flat rate quoted | Real reducing rate | Real rate is |
|---|---|---|
| 5% | 9.15% | 1.83x |
| 6% | 10.85% | 1.81x |
| 7% | 12.50% | 1.79x |
| 8% | 14.13% | 1.77x |
| 9% | 15.71% | 1.75x |
Now keep the flat rate at 6% and change the tenure:
| Tenure | Real reducing rate | Real rate is |
|---|---|---|
| 1 year | 10.90% | 1.82x |
| 2 years | 11.13% | 1.85x |
| 3 years | 11.08% | 1.85x |
| 5 years | 10.85% | 1.81x |
| 7 years | 10.58% | 1.76x |
Two things stand out. The real rate stays at roughly 1.75 to 1.85 times the flat rate across all of these, so the multiplier is steady. And the tenure barely changes it: a flat 6% is already about 10.9% real on a 1-year loan, and still about 10.6% on a 7-year one. As a rough habit, I'd mentally double any flat rate I hear, which is slightly pessimistic but safe.
Check any offer in a minute
Flat rate converter
Enter the loan amount, the flat rate and the tenure you were quoted. You get the EMI, and the real reducing-balance rate hiding behind it.
What to ask before you sign
- "Is this a flat rate or a reducing-balance rate?" Ask it in exactly those words.
- "What's the total amount I'll repay over the full tenure?" Get a number, not a percentage.
- "What other charges are there?" Processing fee, documentation charges and insurance can all be added on top.
- Ask for the sanction letter or the written schedule, so the numbers can be checked, not just quoted.
Compare offers using the real reducing rate, or simply by the total repayment. Those two numbers don't change with how the lender chooses to describe the rate.
Two real-looking offers, side by side
This is where it gets useful. You need ₹8 lakh for a car over 5 years and you have two offers:
| Dealer offer | Bank offer | |
|---|---|---|
| Quoted rate | 6.5% flat | 10.5% reducing |
| Monthly EMI | ₹17,667 | ₹17,195 |
| Total interest | ₹2,60,000 | ₹2,31,707 |
| Real reducing rate | 11.68% | 10.50% |
The dealer's 6.5% looks four points cheaper than the bank's 10.5%. In reality it's the other way round. The dealer's loan costs about ₹28,000 more in total interest, and its real rate is around 11.7%. If you'd gone by the headline, you'd have picked the dearer loan and felt clever doing it.
Why lenders still use flat rates
It isn't always trickery. Flat-rate arithmetic is simple: interest is one multiplication, and the EMI is one division. Sales teams find it easy to explain, and a smaller headline number makes the loan feel affordable. The trouble is only that the number isn't comparable with the reducing-balance rates banks publish. It's most common in dealer-arranged finance and with some non-bank lenders, so those are the places I'd always ask the question.
Where else you'll meet it
Keep an eye out for flat-style pricing in two-wheeler loans, some consumer-durable financing and informal loans between individuals. The same habit applies to all of them: convert to the real rate, or compare total repayment. A third option is to ask the lender, politely, for the annual percentage rate. If they can't give you one, that tells you something too.
Questions people ask
Is flat rate interest legal in India?
It isn't banned, but it must be disclosed properly, and regulators expect lenders to show the effective rate. Flat rates are more common with dealer finance and some non-bank lenders than with direct bank loans.
Is flat rate always more expensive?
For the same quoted number, yes. A flat rate is always higher in real terms than a reducing rate of the same figure, because you never get credit for the principal you've already repaid.
Can I convert a flat rate to a reducing rate by hand?
Not simply. There's no clean formula, because it needs a numerical solution. That's why the converter above exists. A rule of thumb is to multiply by about 1.8 for typical car-loan tenures.
Do banks use flat rates?
Most banks quote reducing-balance rates for home, car and personal loans. If a bank or agent talks about a flat rate, ask for the equivalent annual percentage rate before comparing.
This article is for general information and education. It is not financial, tax or legal advice. Examples use illustrative round numbers and standard formulas. Your lender's actual rates, fees and rules will differ, so check your loan agreement or speak to a qualified adviser before making borrowing or investment decisions.
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