Convert flat interest rate to effective reducing-balance (diminishing) rate — or vice versa. Understand the true cost of your personal, vehicle or business loan.
By Aditya GuptaAccounting & Finance EducatorLast reviewed May 31, 2026Source: RBI
About this converter
Flat-rate quoting is the single most common pricing trick in Indian retail lending. The 10% flat rate on a 5-year ₹5 lakh personal loan actually costs you the equivalent of 18-19% on reducing balance — almost double. This converter translates between the two so you can compare loan offers honestly.
The math: in flat-rate, interest is charged on the original ₹5 lakh every year for 5 years, even as you pay down the principal. In reducing balance (used by RBI-regulated banks for home loans), interest is computed each month on what you still owe — which shrinks. Mathematically, for a 5-year loan, flat ≈ reducing rate ÷ 1.85. So 10% flat ≈ 18.5% reducing.
Where you’ll see flat-rate pricing in India: dealer-financed two-wheeler loans, used-car loans from NBFCs, some consumer-durable EMIs (TV, fridge), and shop-financed gold loans. Where you won’t: nationalised bank home loans, education loans, and most fintech personal loans. RBI rules require regulated lenders to display the Effective Annual Rate (EAR) on the sanction letter — that’s the reducing-balance equivalent. Always ask for it.
Frequently Asked Questions
What’s the difference between flat and reducing rate?
Flat rate charges interest on the original loan amount every month, even after you’ve paid back part of it. Reducing-balance charges interest only on the outstanding principal. A 10% flat rate is roughly 17-19% reducing balance — almost double the effective cost.
Why do lenders quote flat rates?
They sound lower. A 10% flat rate looks better than 18.5% reducing balance — but they’re the same loan. Dealer-financed two-wheeler and used-car loans are notorious for flat-rate quoting.
Is RBI’s MCLR a flat or reducing rate?
MCLR (and now repo-linked rates) are reducing balance rates by RBI mandate. All bank home loans, education loans, and most personal loans must use reducing balance.
How do I check what rate I’m actually paying?
Read the loan agreement — it states whether interest is computed on ‘flat’ or ‘reducing/diminishing’ balance. If it doesn’t, ask. Use this converter to translate to the effective rate.
Are zero-interest EMI offers really zero?
Usually not. The ‘interest’ is buried as a processing fee, GST on processing, or a hidden cost in the product price. Compute the equivalent reducing rate to expose the real cost.
In a flat rate loan, interest is calculated on the full principal throughout — even though you’re repaying it monthly. In a reducing balance loan, interest is only on the outstanding principal. A flat rate of 10% = ~18% reducing balance. Always ask lenders for the reducing rate (APR/IRR) when comparing loans.
Caution: Many NBFC personal loans and vehicle loans are quoted at flat rates. A 10% flat rate sounds cheap but is actually ~18% reducing balance. Always compare reducing rates.
Flat vs Reducing Rate — FAQ
Why do lenders use flat rates?
Flat rates make loans appear cheaper — a 10% flat rate sounds much lower than 18% reducing balance even though they’re equivalent. Some NBFCs, consumer finance companies and older vehicle loans still quote flat rates. The RBI mandates banks to quote APR (reducing balance equivalent) for transparency.
Which is better — flat or reducing rate?
Neither inherently — what matters is the total interest paid. A reducing balance loan costs less total interest if you prepay early. A flat rate loan’s total interest is fixed regardless. Always compare the total interest outflow and EMI, not just the headline rate.
How do I quickly approximate flat to reducing?
A rough rule of thumb: Reducing Rate ≈ Flat Rate × 1.8 to 2. So 10% flat ≈ 18–20% reducing. This varies slightly with tenure — shorter tenures have a higher multiplier. Use this converter for an exact calculation.
