"Get a car loan at just 7% flat!" sounds cheaper than a bank's 12% reducing rate — but it isn't. The flat 7% loan actually costs more. Understanding flat vs reducing interest is one of the most useful money skills you can have, because lenders quote flat rates precisely because they look smaller. Here's how it works.
The Two Methods
| Method | Interest charged on… |
|---|---|
| Reducing balance | The outstanding principal, which falls every month as you repay |
| Flat rate | The full original principal, for the entire tenure |
That single difference is why the same headline rate gives wildly different costs.
A Worked Example — ₹8 Lakh for 5 Years
At 10% Flat
- Total interest = 8,00,000 × 10% × 5 = ₹4,00,000
- Total payable = ₹12,00,000
- EMI = 12,00,000 ÷ 60 = ₹20,000
At 10% Reducing
- EMI = ₹16,997
- Total interest = ₹2,19,820
- Total payable = ₹10,19,820
Same "10%", but the flat loan costs ₹1.8 lakh more. In fact, that 10% flat rate is equivalent to roughly a 17–18% reducing rate.
The Rule of Thumb
For medium tenures, the effective reducing rate ≈ flat rate × 1.8 to 1.9. So:
| Flat rate quoted | ≈ Effective reducing rate |
|---|---|
| 6% flat | ~11% reducing |
| 8% flat | ~14.5% reducing |
| 10% flat | ~18% reducing |
| 12% flat | ~21.5% reducing |
Which Loans Use Which?
- Reducing balance: home loans, most personal loans, credit cards.
- Flat rate: some car loans, two-wheeler loans, gold loans, and appliance/phone EMI financing.
If a quoted rate looks surprisingly low, it's often flat. Always ask the lender to confirm the method.
How to Protect Yourself
- Ask: "Is this rate flat or reducing?"
- If flat, convert it to the effective reducing rate before comparing offers.
- Compare the total payable, not just the EMI or the headline rate.
Check the Real Cost
Use our Flat vs Reducing Rate Calculator to see exactly what a flat rate costs as an effective reducing rate, then put two real offers head to head with the Compare Two Loans tool. For a standard reducing-balance loan, the EMI Calculator gives your full schedule.