What is the difference between flat and reducing rate?

Flat-rate interest is calculated on the full original principal for the entire tenure. Reducing-balance interest is calculated on the outstanding principal after each EMI. For the same quoted rate, flat costs almost 1.8× more than reducing.

EMI vs Flat Rate vs Reducing Balance Interest — A Plain-English Guide (2026)

Q: Which is better for the borrower?

Reducing balance is always cheaper for the borrower at the same quoted rate.

Updated 9 May 2026 · 6 min read · VyajPay Editorial

EMI flat rate and reducing balance interest calculator illustration

If a money lender quotes you "12% interest," your next question should be: flat or reducing? The same number means very different things. This guide breaks down all three concepts with examples and a free calculator.

Definitions

EMI (Equated Monthly Instalment): A fixed monthly payment that combines principal + interest.
Flat rate: Interest is computed on the full original principal across the entire tenure.
Reducing balance: Interest is recomputed each month on the remaining outstanding principal.

Worked example — ₹1,00,000 loan, 12% per year, 2 years

Flat rate

Total interest = 1,00,000 × 12% × 2 = ₹24,000 Total to repay = ₹1,24,000 EMI = 1,24,000 / 24 = ₹5,167

Reducing balance

EMI = [P × r × (1+r)^n] / [(1+r)^n − 1] = [1,00,000 × 0.01 × (1.01)^24] / [(1.01)^24 − 1] = ₹4,707 (approx) Total to repay = ₹4,707 × 24 = ₹1,12,968 Total interest = ₹12,968

The catch

At the SAME quoted 12%, flat costs almost 2× the interest of reducing (₹24,000 vs ₹12,968). The "effective annual rate" of a 12% flat loan over 2 years is roughly 21–22% reducing-equivalent.

Method	EMI	Total Interest	Effective Rate
Flat 12%	₹5,167	₹24,000	~22% reducing equivalent
Reducing 12%	₹4,707	₹12,968	12% (true)

When each is used

Flat rate: Local money lenders, vehicle finance from non-banks, some gold loans, BNPL.
Reducing balance: All bank loans (home, personal, auto), most NBFC personal loans, regulated lending.

How to convert quoted flat to true rate

Approximate formula: true reducing rate ≈ flat rate × (2n / (n+1)), where n is the number of EMIs.

For 24 EMIs: 12% flat ≈ 12% × 1.92 ≈ 23% reducing. Always ask your lender to convert before signing.

Why this matters for VyajPay users

VyajPay supports both methods. As a lender, choose the one that matches what you negotiated. As a borrower being lent to, ask the lender to use reducing-balance EMI in the app — it's transparent and the math is unambiguous.

Try the free EMI calculator

EMI Calculator All Calculators

FAQ

Which is better for the borrower?

Reducing-balance, always — at the same quoted rate it costs roughly half the interest.

Why do lenders quote flat?

Because the headline number sounds smaller than the equivalent reducing rate.

Does VyajPay show the effective rate?

Yes — when you create a loan with a flat rate, the app shows you the equivalent reducing rate so you and the borrower understand the true cost.