Reviewed by Finin2min Editorial Desk · Last reviewed 11 August 2026
Convert a flat-interest quote into total repayment and compare it with a reducing-balance EMI loan.
Compare loan quotations
A flat rate looks lower because interest is charged on original principal for the entire tenure.
Measure
Flat / Reducing
Monthly payment
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Total interest
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Total repayment including fee
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Approximate flat-loan annualised IRR
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How This Is Calculated
A flat-rate loan charges interest on the full original principal for the entire tenure, while a reducing-balance loan charges interest only on the outstanding balance, which shrinks with each payment — this means a flat rate that looks similar to a reducing rate on paper actually corresponds to a much higher effective (reducing-equivalent) rate, which this calculator solves for and shows explicitly.
Frequently Asked Questions
Why does a flat interest rate cost more than the same reducing-balance rate?
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Because flat-rate interest is charged on the original principal for the whole tenure, even as you pay down the balance — a reducing-balance loan only charges interest on what's actually still owed, so the same stated percentage rate results in meaningfully lower total interest under reducing balance.
How much higher is the effective rate of a flat-rate loan?
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Roughly, a flat rate can correspond to an effective (reducing-balance-equivalent) rate of nearly double, though the exact multiple depends on tenure — always convert a quoted flat rate to its effective rate before comparing it against a reducing-balance loan offer.
Evidence and verification checklist
Confirm the current, in-force text governing Flat Rate vs Reducing Balance Loan Comparator on the official source linked above - the summary on this page is an implementation aid, not a substitute for it.
Record the exact event/transaction date, since the applicable version of the law, form or threshold can change between the date of the underlying event and today.
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Before relying on this page
This page is a structured implementation summary, not the operative legal text. Portal or process acceptance of a filing does not by itself establish legal compliance - the underlying classification, authority, evidence and timeline still have to be independently correct. Where the facts are contested, high-value, or time-barred if delayed, verify the current position with the official source and, where appropriate, a qualified professional before acting.
Scope: Compares a flat-rate loan (interest charged on the original principal throughout the tenure) against a reducing-balance loan (interest charged only on the outstanding balance) at the same nominal rate, and computes the reducing-balance-equivalent effective rate of the flat-rate loan.
Calculation logic
Flat-rate EMI = (Principal + (Principal × Flat rate × Tenure in years)) ÷ Number of months — total interest is fixed at Principal × Flat rate × Tenure regardless of repayment progress.
Reducing-balance EMI = P × r × (1+r)n / ((1+r)n − 1), where r is the monthly rate and n is the number of months, per the standard amortising formula.
Solve for the reducing-balance rate that would produce the same EMI as the flat-rate loan, to show the flat-rate loan's true (higher) effective interest cost — flat-rate loans are commonly quoted at a lower headline rate but cost meaningfully more than the same headline rate under reducing balance.
Inputs and assumptions
This comparison assumes both loans have the same principal and tenure — only the interest-calculation method differs.
The effective-rate conversion uses numerical iteration to find the reducing-balance rate matching the flat-rate EMI, since there is no closed-form algebraic solution.
Exclusions and edge cases
Does not include processing fees or other charges that may differ between flat-rate and reducing-balance loan offers in the market — this is purely an interest-methodology comparison.
Real-world flat-rate loan products (e.g., certain consumer-durable or vehicle loans) may have additional structuring (e.g., fixed EMI regardless of computed value) not modelled here.
Sources
No specific external regulatory source applies beyond general market-linked instrument mechanics.
Review status: reviewed and approved by CA Nikhil Gupta on 17 July 2026.
Guides that use this calculator
Background, worked examples and the rules behind these numbers.