Simple Interest Calculator
Calculate simple interest and compare it with compound interest to see the power of compounding.
Simple Interest
₹24,000
Principal
₹1.00 L
Total Amount
₹1.24 L
| Year | Interest for Year | Total Interest | Total Amount |
|---|---|---|---|
| Year 1 | ₹8,000 | ₹8,000 | ₹1.08 L |
| Year 2 | ₹8,000 | ₹16,000 | ₹1.16 L |
| Year 3 | ₹8,000 | ₹24,000 | ₹1.24 L |
About the Simple Interest Calculator
Simple interest is the foundation of financial mathematics. While compound interest dominates most real-world products, understanding the difference between SI and CI is fundamental to recognizing when you are paying more than you think (credit cards, personal loans) or earning less than you could (short-term FDs vs long-term MFs). The power of compounding - Einstein's alleged 'eighth wonder of the world' - is most viscerally understood by comparing simple interest returns side by side with compound interest returns over long periods.
Simple Interest Formula
SI = (P x R x T) / 100 | Amount = P + SI
P = Principal (initial investment or loan amount) | R = Rate of interest per annum (%) | T = Time period in years
Worked Example
1 lakh invested at 8% for 10 years
Simple Interest: 80,000 | Total Amount: 1,80,000 | vs Compound Interest (annual): 1,15,892 interest, Total 2,15,892 - compounding earns 35,892 more (44% extra)
Tips & Insights
- 1
Most bank FDs use compound interest (quarterly compounding), not simple interest. Effective yield is higher than the stated rate.
- 2
The Rule of 72: divide 72 by the interest rate to find years to double (compound interest). At 8%, money doubles in 9 years. At 12%, 6 years.
- 3
Simple interest is more common in short-term instruments (< 1 year) where compounding frequency has minimal impact.
- 4
Credit card debt charges compound interest daily or monthly at 36-42% p.a. Even a small outstanding balance grows explosively.
- 5
Personal loans state an annual rate but use reducing balance method (a form of compound interest). Always calculate total payout, not just EMI.
Why this matters for you
Simple interest calculations are the entry point into financial literacy. A student who understands SI can then grasp why CI on a 10-year investment earns 40% more, why credit card debt at 3%/month destroys wealth, and why starting a SIP at 25 vs 35 makes a difference of crores at retirement. The SI vs CI comparison in this calculator is designed to make that compounding gap visceral and memorable.