Compound Interest Calculator
Estimate investment growth with compounding for lump sum and periodic contributions. Includes CAGR, inflation-adjusted results, charts, and year-wise breakdown.
Inputs
Results
Charts
Year-wise Breakdown
Compound Interest Calculator – Calculate Returns with Monthly or Lump Sum Investments
Use this Compound Interest Calculator to estimate how your money can grow over time through compounding. Whether you invest a lump sum, make monthly investments, or stop investing early and stay invested longer, this calculator helps you understand the impact of time, compounding frequency, and inflation.
This calculator is designed for clarity, accuracy, and learning — not promotion.
What is Compound Interest?
Compound interest is the process where your investment earns returns not only on the original amount invested, but also on the interest already earned.
In simple terms: Your money starts earning money, and then that money earns more money.
The longer you stay invested, the more powerful compounding becomes.
How This Compound Interest Calculator Works
This calculator models real-world investing patterns, including:
- Lump sum investments
- Monthly or yearly contributions
- Different investment duration and stay invested duration
- Monthly, quarterly, semi-annual, or annual compounding
- Inflation-adjusted (real) returns
- Annual deposit increase to reflect salary growth (step-up investing)
Growth before adjusting for inflation.
Annualized return based on the timing of your cash flows.
Key Inputs Explained
Use the inputs below to match your investing scenario. The sections are collapsible so you can scan what matters.
1) Investment Type▼
Choose between:
- Lump Sum — one-time investment amount.
- Periodic Investment — monthly or yearly contributions.
2) Investment Duration vs Stay Invested Duration▼
These two are intentionally different to reflect real behavior:
- Investment duration — how long you actively invest money.
- Stay invested duration — how long your money remains invested and continues compounding, even after contributions stop.
Example: You contribute for 10 years, then stop, but you keep the corpus invested for another 5 years.
3) Expected Annual Rate of Return▼
This is the assumed annual return used for compounding calculations. It’s an estimate, not a guarantee. Consider trying multiple rates to understand best-case vs conservative scenarios.
4) Compounding Frequency▼
Choose how often interest is compounded:
- Annually
- Semi-annually
- Quarterly
- Monthly
More frequent compounding typically increases the effective annual return when the nominal rate is the same.
5) Annual Deposit Increase (Advanced)▼
If enabled, your periodic investment amount increases every year by a fixed percentage. This models salary growth or step-up SIPs.
6) Inflation Adjustment▼
When enabled, the calculator shows real (inflation-adjusted) returns to help you understand actual purchasing power.
What Results Does the Calculator Show?
- Total amount invested
- Final corpus value
- Total interest earned
- CAGR (effective annual return)
- Time to double investment (approx.)
- Interactive charts for portfolio growth over time
- Principal vs interest contribution
- Detailed year-wise breakdown for deeper analysis
Why CAGR Can Be Lower Than Expected Returns
In periodic investing, money enters the market gradually. Some contributions get less time to compound than others.
CAGR reflects the time-weighted experience of your money, not just the assumed return rate. This is normal and expected.
Why Staying Invested Matters More Than Investing Longer
Many investors focus on how long they invest, but the real power comes from how long they stay invested.
Stopping contributions early but remaining invested allows compounding to continue — often contributing more to final wealth than fresh investments.
Who Should Use This Calculator?
- Long-term investors
- SIP / periodic investors
- Retirement planners
- Anyone comparing lump sum vs periodic investing
- Users trying to understand compounding clearly
Frequently Asked Questions
Is this compound interest calculator accurate?▼
It produces mathematically accurate estimates based on the inputs you enter (contribution pattern, compounding frequency, and rate assumptions). Market returns can vary in real life, so treat results as an educational projection—not a guarantee.
Does this calculator include inflation?▼
Yes. Enable inflation adjustment to see real returns—an estimate of purchasing power after inflation.
Can I calculate SIP returns?▼
Yes. Choose periodic investment mode and set the contribution frequency to monthly (SIP-style). The calculator models contributions over time and shows both nominal and inflation-adjusted outcomes.
Why is CAGR different from the expected return?▼
CAGR reflects when money is invested, not just how much. With periodic investing, most contributions enter later and get less time to compound, so the “effective” annualized return for the whole cash-flow stream can be lower than the assumed rate.
What is the difference between investment duration and stay invested duration?▼
Investment duration is how long you actively add money. Stay invested duration is how long your money remains invested and continues compounding (even after contributions stop). This mirrors real scenarios where people stop investing but don’t withdraw immediately.