Question 1

What is the simple interest formula?

Accepted Answer

Simple Interest = Principal × Rate × Time, or I = P × R × T. The principal (P) is the initial amount, the rate (R) is the annual interest rate as a decimal (e.g. 8% = 0.08), and time (T) is in years. The total amount at the end is A = P + I.

Question 2

What is the difference between simple interest and compound interest?

Accepted Answer

Simple interest is calculated only on the principal amount — the interest does not accumulate on previously earned interest. Compound interest is calculated on the principal plus any interest already earned, causing the balance to grow faster over time. For the same principal, rate, and period, compound interest always results in a higher final amount than simple interest.

Question 3

When is simple interest used in practice?

Accepted Answer

Simple interest is used for short-term personal loans, auto loans, some fixed deposits, US savings bonds, and invoice financing. It is also the basis of most consumer instalment loans where the daily balance determines the interest charge.

Question 4

How do I calculate interest for months instead of years?

Accepted Answer

Divide the number of months by 12 to get the time in years. For example, 6 months = 0.5 years. Use the calculator's months input to do this automatically — it converts months to the fractional year value before applying the formula.

Question 5

What is the maturity value?

Accepted Answer

The maturity value (also called the total amount or future value) is the principal plus the total interest earned at the end of the period: A = P + I. If you invested ₹10,000 at 8% per year for 2 years, the interest is ₹1,600 and the maturity value is ₹11,600.

Simple Interest

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Simple interest formula