Compound Interest Calculator India 2026 - CI Formula, Table & Investment Growth
TL;DR
Compound interest is the "interest on interest" that makes your money grow exponentially over time. The formula A = P(1 + r/n)^(nt) calculates the final amount based on principal, rate, compounding frequency, and time. In India, FDs compound quarterly, PPF annually, and savings accounts calculate interest daily. Understanding CI vs SI can mean lakhs of difference over 20-30 years. Key Facts:
- CI Formula: A = P(1 + r/n)^(nt), where P = principal, r = annual rate, n = times compounded per year, t = years
- ₹1 lakh at 10% grows to ₹6.73 lakh in 20 years (CI) vs ₹3 lakh (SI)
- Rule of 72: Divide 72 by interest rate to find doubling time (72/10 = 7.2 years)
- Monthly compounding gives slightly better returns than annual compounding
- PPF compounds annually; FDs compound quarterly; savings accounts compound daily
Compound Interest Formula Explained
The standard compound interest formula is:
A = P x (1 + r/n)^(n x t)Where:
A = Final amount (principal + interest)
P = Principal (initial investment)
r = Annual interest rate (as decimal, e.g., 10% = 0.10)
n = Number of times interest compounds per year
t = Number of years
Compound Interest (CI) = A - P
Compounding Frequencies
| Frequency | n value | Common In |
|---|---|---|
| Annually | 1 | PPF, NSC |
| Semi-annually | 2 | Some bonds |
| Quarterly | 4 | Bank FDs |
| Monthly | 12 | Recurring deposits |
| Daily | 365 | Savings accounts |
Example Calculation: ₹1,00,000 at 10% for 5 Years
Principal (P): ₹1,00,000
Rate (r): 10% = 0.10
Time (t): 5 yearsAnnual compounding (n=1):
A = 1,00,000 x (1 + 0.10/1)^(1x5)
A = 1,00,000 x (1.10)^5
A = 1,00,000 x 1.61051
A = ₹1,61,051
CI = ₹61,051
Quarterly compounding (n=4):
A = 1,00,000 x (1 + 0.10/4)^(4x5)
A = 1,00,000 x (1.025)^20
A = 1,00,000 x 1.63862
A = ₹1,63,862
CI = ₹63,862
Monthly compounding (n=12):
A = 1,00,000 x (1 + 0.10/12)^(12x5)
A = 1,00,000 x (1.00833)^60
A = ₹1,64,530
CI = ₹64,530
---
The Power of Compounding: Growth Over Time
See how ₹1,00,000 grows at different rates with annual compounding:
| Years | 7% (PPF-like) | 10% (Equity MF) | 12% (Aggressive MF) | 15% (High Growth) |
|---|---|---|---|---|
| 5 | ₹1,40,255 | ₹1,61,051 | ₹1,76,234 | ₹2,01,136 |
| 10 | ₹1,96,715 | ₹2,59,374 | ₹3,10,585 | ₹4,04,556 |
| 15 | ₹2,75,903 | ₹4,17,725 | ₹5,47,357 | ₹8,13,706 |
| 20 | ₹3,86,968 | ₹6,72,750 | ₹9,64,629 | ₹16,36,654 |
| 30 | ₹7,61,226 | ₹17,44,940 | ₹29,95,992 | ₹66,21,177 |
---
Compound Interest vs Simple Interest
| Feature | Compound Interest (CI) | Simple Interest (SI) |
|---|---|---|
| Formula | A = P(1+r/n)^(nt) | A = P(1+rt) |
| Interest earned on | Principal + accumulated interest | Only on principal |
| Growth pattern | Exponential | Linear |
| Better for | Long-term investors | Short-term loans |
| Example (₹1L, 10%, 10y) | ₹2,59,374 | ₹2,00,000 |
| Difference | -- | ₹59,374 less |
CI vs SI: ₹5,00,000 at 8% Over Different Periods
| Years | Simple Interest | Compound Interest (Quarterly) | Difference |
|---|---|---|---|
| 3 | ₹6,20,000 | ₹6,33,393 | ₹13,393 |
| 5 | ₹7,00,000 | ₹7,42,974 | ₹42,974 |
| 10 | ₹9,00,000 | ₹11,04,020 | ₹2,04,020 |
| 20 | ₹13,00,000 | ₹24,38,656 | ₹11,38,656 |
---
Rule of 72: Quick Mental Math
The Rule of 72 tells you approximately how many years it takes to double your money:
Doubling Time = 72 / Annual Interest Rate
| Interest Rate | Doubling Time |
|---|---|
| 6% | 12 years |
| 7% (PPF) | 10.3 years |
| 8% (FD) | 9 years |
| 10% (Balanced MF) | 7.2 years |
| 12% (Equity MF) | 6 years |
| 15% (Aggressive) | 4.8 years |
---
Compound Interest in Indian Investment Products
| Product | Interest Rate | Compounding | Lock-in |
|---|---|---|---|
| Savings Account | 2.5-3.5% | Daily | None |
| Bank FD | 6.5-7.5% | Quarterly | 7 days - 10 years |
| PPF | 7.1% | Annually | 15 years |
| NSC | 7.7% | Annually | 5 years |
| Sukanya Samriddhi | 8.2% | Annually | 21 years |
| Post Office RD | 6.7% | Quarterly | 5 years |
Frequently Asked Questions
Q: How is compound interest different from simple interest in India?
Simple interest is calculated only on the original principal amount throughout the investment period. Compound interest is calculated on the principal plus all previously accumulated interest. For example, ₹1,00,000 at 10% for 10 years earns ₹1,00,000 as SI but ₹1,59,374 as CI (annual compounding) -- a difference of ₹59,374.
Q: Which Indian investments use compound interest?
Almost all Indian savings and investment products use compound interest. Bank FDs compound quarterly, PPF and NSC compound annually, savings accounts compound daily or quarterly, and recurring deposits compound quarterly. Only certain government bonds and short-term instruments may use simple interest.
Q: Does SIP in mutual funds use compound interest?
Mutual fund SIPs benefit from compounding because returns are reinvested. However, mutual fund returns are not "interest" but market-linked returns. The compounding effect occurs because your gains generate further gains. Over 15-20 years, SIP compounding can create substantial wealth -- a ₹5,000/month SIP at 12% for 20 years builds approximately ₹49.96 lakh from ₹12 lakh invested.
Q: What is the best compounding frequency for maximizing returns?
More frequent compounding gives slightly higher returns. Daily compounding is better than monthly, which is better than quarterly, which is better than annual. However, the practical difference between monthly and daily compounding is minimal. The bigger factors are interest rate and investment duration.
---
Conclusion
Compound interest is the most powerful force in wealth building. The three factors that matter most are: rate of return (choose investments wisely), time (start as early as possible), and consistency (keep investing regularly). Even modest monthly contributions can grow into substantial wealth over 20-30 years thanks to the exponential nature of compounding. Calculate your compound interest: CI Calculator → | CI Table →