Flat to Reducing Rate Conversion: Table, Formula and Calculator

Updated 2026-09-14·6 min read·Privena Editorial

Dealers, consumer-durable finance desks and informal lenders often quote a flat rate, because a small number sells better. To compare that quote against a bank or NBFC offer you have to convert it to a reducing-balance rate first. This page gives you the formula, a ready-made table and a live converter.

Flat vs Reducing Rate Calculator

Live comparison

Enter the rate a lender quoted you. We show the EMI both ways, and the reducing rate that flat quote really equals.

Loan amount₹50,000
₹5K₹10L
Quoted interest rate10.0% p.a.
5%36%
Tenure24 months
3 mo84 mo
Flat 10.0%
Monthly EMI
₹2,500
Total interest
₹10,000
Total payable
₹60,000
Reducing 10.0%
Monthly EMI
₹2,307
Total interest
₹5,374
Total payable
₹55,374
A flat rate of 10.0% p.a. over 24 months is the same cost as a reducing rate of about 18.2% p.a. — you pay ₹4,626 more than the reducing-balance loan at the same headline rate.

The conversion formula

Reducing rate ≈ flat rate × (2N ÷ (N + 1)), where N is the number of monthly instalments. For a 12-month loan the multiplier is about 1.85; for 24 months about 1.92; for 36 months about 1.95. The multiplier never quite reaches 2.

Flat to reducing rate conversion table

Flat rate quoted12-month loan24-month loan36-month loan
6% flat~11.1% reducing~11.5% reducing~11.7% reducing
8% flat~14.8% reducing~15.4% reducing~15.6% reducing
10% flat~18.5% reducing~19.2% reducing~19.5% reducing
12% flat~22.2% reducing~23.0% reducing~23.4% reducing
14% flat~25.8% reducing~26.9% reducing~27.3% reducing
15% flat~27.7% reducing~28.8% reducing~29.2% reducing
18% flat~33.2% reducing~34.6% reducing~35.0% reducing
24% flat~44.3% reducing~46.1% reducing~46.7% reducing

Indicative equivalents using the 2N ÷ (N + 1) approximation. Use the converter above for an exact figure on your own quote.

Converting in the other direction

To go from reducing to flat, divide instead of multiplying: flat ≈ reducing rate × (N + 1) ÷ 2N. A 28% reducing-rate loan over 24 months is roughly a 14.6% flat quote — useful when a lender insists on comparing like with like on their terms.

A real comparison

A dealer offers ₹60,000 over 24 months at 9% flat: interest is ₹10,800 and the EMI ₹2,950. A bank offers the same amount at 16% reducing: interest is about ₹8,500 and the EMI ₹2,854. The 16% offer looks nearly twice as expensive and is in fact more than ₹2,000 cheaper.

Rule of thumb: mentally double any flat rate before comparing it to a bank or NBFC quote. If the doubled number looks bad, the loan is bad.

How Privena prices its loans

Privena quotes only reducing-balance rates, with the APR — interest plus processing fee, annualised — printed in your Key Fact Statement before you accept. There is no flat-rate product and no conversion for you to do.

Frequently asked questions

How do you convert a flat rate to a reducing rate?
A quick approximation is reducing rate ≈ flat rate × (2N ÷ (N + 1)), where N is the number of EMIs. For a 24-month loan that is about 1.92 times the flat rate. For an exact figure, use the converter, which solves for the reducing rate that produces the same monthly outflow.
Is a 10% flat rate the same as 10% reducing?
No. Over 24 months a 10% flat rate is worth roughly 19% on a reducing basis, because the flat structure keeps charging interest on principal you have already repaid.
Why does the conversion factor change with tenure?
The longer the tenure, the more principal you have repaid by the time later interest is charged, so the gap between the flat and reducing structures widens. The factor rises from about 1.85 over 12 months towards 2 over long tenures.
Which rate should I compare between lenders?
Neither in isolation. Compare the APR in each Key Fact Statement, which annualises the reducing-balance interest together with the processing fee and other mandatory charges.

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