Money calculator

Simple interest calculator

Find the interest and total amount, or work backwards to the rate or time. The working is shown, so it's handy for maths homework too.

Find

Interest Rate Time

Principal (₹)

Rate (% per year)

Time

Simple interest

–

–total amount (P + SI)

Simple interest formula

SI = P × R × T ÷ 100 A = P + SI

P is the principal, R the rate % per year and T the time in years. Change months to years by dividing by 12, and days by dividing by 365. To find the rate, use R = SI × 100 ÷ (P × T). To find the time, use T = SI × 100 ÷ (P × R).

Where is simple interest used in real life?

Short FDs, some personal and gold loans, and money lent between people. Most savings and long loans use compound interest instead.

Example: ₹10,000 at 6% for 3 years

SI = 10,000 × 6 × 3 ÷ 100 = ₹1,800. Amount = 10,000 + 1,800 = ₹11,800.