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Simple Interest Calculator

An interest calculator for simple interest: work out the interest and the total amount payable or receivable on any sum.

₹
%
years

Use decimals for months, e.g. 1.5

Total amount
₹59,000
Interest
₹9,000

Formula

SI = P × R × T ÷ 100 and Amount = P + SI, where P is the principal, R the yearly rate in % and T the time in years.

Example

₹10,000 at 8% for 3 years: SI = 10,000 × 8 × 3 ÷ 100 = ₹2,400, so the total is ₹12,400.

Where simple interest is used

  • Some personal and gold loans, and informal lending.
  • Short-term calculations and exam problems.
  • Most bank deposits use compound interest instead: the compound interest calculator shows the difference.

Frequently asked questions

How do I enter months?

Convert them to years: 6 months = 0.5, 18 months = 1.5.

How do I find the rate if I know the interest?

R = SI × 100 ÷ (P × T). For example, ₹1,800 interest on ₹20,000 over 2 years means R = 1,800 × 100 ÷ 40,000 = 4.5%.

Simple vs compound interest?

Simple interest is charged on the original principal only. Compound interest also earns on past interest, so it grows faster over time. ₹10,000 at 8% for 3 years earns ₹2,400 simple interest but ₹2,597 compounded yearly.

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