Compound Interest Calculator
See how your money grows with compound interest — choose principal, rate, time and compounding frequency, with a year-by-year breakdown.
About the Compound Interest Calculator
Compound interest is interest earned on interest — the engine behind long-term wealth building. This compound interest calculator shows the final amount and total interest for any principal, annual rate and time period, with your choice of compounding frequency: yearly, half-yearly, quarterly or monthly. A year-by-year table breaks down exactly how the balance snowballs.
The formula is A = P × (1 + r/m)^(m×t), where P is the principal, r the annual rate as a decimal, m the number of compounding periods per year and t the time in years. More frequent compounding grows money slightly faster: ₹1,00,000 at 8% for 10 years becomes ₹2,15,892 with yearly compounding but ₹2,21,964 with monthly compounding.
Use it to model fixed deposits (Indian banks typically compound FDs quarterly), recurring savings goals, bond reinvestment or simply to compare offers. The year-by-year table makes the acceleration visible — in later years your annual interest can exceed what the entire first few years earned, which is why starting early matters so much.
How to Use the Compound Interest Calculator
- 1Enter the principal amount you are investing or depositing.
- 2Enter the annual interest rate and the time period in years.
- 3Pick the compounding frequency — yearly, half-yearly, quarterly or monthly.
- 4Review the final amount, total interest and the year-by-year growth table.
Frequently Asked Questions
What is the compound interest formula?
A = P(1 + r/m)^(mt), where P is the principal, r the annual rate as a decimal, m the compounding periods per year and t the years. Total interest is A − P. For ₹50,000 at 7% compounded quarterly for 5 years: 50,000 × (1 + 0.0175)^20 ≈ ₹70,760.
What is the difference between simple and compound interest?
Simple interest is charged only on the original principal, so it grows linearly: ₹1 lakh at 8% earns ₹8,000 every year. Compound interest is calculated on principal plus accumulated interest, so it grows exponentially — the same deposit earns ₹8,000 in year one but over ₹15,000 in year ten.
Does compounding frequency really matter?
Yes, though the effect is modest at typical rates. Moving from yearly to monthly compounding at 8% raises the effective annual yield from 8% to about 8.30%. The gap widens with higher rates and longer periods. Indian bank FDs usually compound quarterly, so choose quarterly to model them accurately.
How long does it take to double my money?
The Rule of 72 gives a quick estimate: divide 72 by the annual rate. At 8%, money doubles in about 9 years; at 12%, about 6 years. This calculator gives the exact figure — enter your rate and scan the year-by-year table for the year the balance passes twice your principal.
Can I use this calculator for fixed deposits (FDs)?
Yes. Enter the FD amount as principal, the bank's quoted rate, the tenure in years, and select quarterly compounding — the convention used by most Indian banks. The final amount will closely match the bank's maturity value; small differences can arise from day-count conventions and TDS deductions.