Calculate simple interest on principal amount
Simple Interest Calculator is a comprehensive financial calculator designed to help you calculate simple interest on principal amount. Planning finances requires absolute precision; this calculator provides instant accurate projections for EMIs, compounding, loans, and investment portfolio returns.
Simple interest SI = P × R × T ÷ 100, where P is the principal, R is the annual rate in percent and T is the time in years. Total amount = P + SI. For ₹1,00,000 at 10% for 5 years, SI = 1,00,000 × 10 × 5 ÷ 100 = ₹50,000, and the total is ₹1,50,000.
Convert the time into years: months ÷ 12, or days ÷ 365. For ₹1,00,000 at 12% for 6 months, T = 0.5, so SI = 1,00,000 × 12 × 0.5 ÷ 100 = ₹6,000. This calculator takes time in whole years, so do this conversion yourself for shorter periods.
Simple interest is calculated only on the original principal, so it grows by the same amount each year. Compound interest is calculated on the principal plus accumulated interest, so it grows faster. On ₹1,00,000 at 10% for 5 years, simple gives ₹1,50,000 while yearly compounding gives about ₹1,61,051.
Rearrange the formula: R = SI × 100 ÷ (P × T) and T = SI × 100 ÷ (P × R). For example, if ₹1,00,000 earns ₹50,000 in 5 years, R = 50,000 × 100 ÷ (1,00,000 × 5) = 10% per year. The calculator computes the interest and total from principal, rate and time.
It is used in some short-term loans, informal lending, certain bonds and school-level maths problems, where interest is not added back to the principal. Bank deposits and most EMI loans work differently: FDs generally compound, and loans charge interest on the reducing balance. Always check how the lender or bank calculates it.
It shows the principal, the simple interest and the total amount, plus a chart of how the total amount and the interest grow each year over your chosen period of up to 30 years. Because the interest is simple, the line rises by the same amount every year.
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A reducing interest rate means interest is charged only on the remaining outstanding principal balance at the end of each period, rather than the initial loan amount.