Loans

How Loan Interest Works

Most loans charge interest on the reducing outstanding balance, so interest falls as you repay. A flat rate charges on the original amount throughout and is effectively costlier.

Last updated2026-06-01· Educational content, not financial advice

Key Takeaways

  • Reducing-balance interest is charged on what you still owe.
  • Flat-rate interest is charged on the original principal throughout.
  • The same flat rate is more expensive than the same reducing rate.
  • Always compare loans on the effective (reducing-balance) rate.

Reducing-balance interest

In a reducing-balance loan, interest each period is calculated on the outstanding balance. As you repay principal, the balance shrinks, so the interest portion of each EMI falls over time. This is how standard EMIs work.

Flat-rate interest

A flat-rate loan charges interest on the full original principal for the entire tenure, regardless of how much you have repaid. Because you are effectively paying interest on money you have already returned, a flat rate is more expensive than the same-numbered reducing-balance rate.

Comparing fairly

When comparing loan offers, convert everything to an effective reducing-balance basis, or compare the total interest paid. A low-looking flat rate can cost more than a higher reducing rate. The EMI calculator uses the reducing-balance method and shows total interest so you can compare offers on a consistent basis.

Sources

We reference primary and official sources. Rate- and rule-dependent details must be verified against the latest official information.

Disclaimer: This article is for general education only and is not investment, tax, or financial advice. Statutory rates, tax rules, and regulations change over time — verify current figures with official primary sources before acting.