liminfoCompound Interest Calculator
Free web tool: Compound Interest Calculator
Final Amount
106,639,017
Total Contributed
70,000,000
Total Interest
36,639,017
| Year | Total Contributed | Interest Earned | Total Balance |
|---|---|---|---|
| Year 1 | 16,000,000 | 919,193 | 16,919,193 |
| Year 2 | 22,000,000 | 2,338,576 | 24,338,576 |
| Year 3 | 28,000,000 | 4,294,306 | 32,294,306 |
| Year 4 | 34,000,000 | 6,825,157 | 40,825,157 |
| Year 5 | 40,000,000 | 9,972,703 | 49,972,703 |
| Year 6 | 46,000,000 | 13,781,527 | 59,781,527 |
| Year 7 | 52,000,000 | 18,299,431 | 70,299,431 |
| Year 8 | 58,000,000 | 23,577,675 | 81,577,675 |
| Year 9 | 64,000,000 | 29,671,224 | 93,671,224 |
| Year 10 | 70,000,000 | 36,639,017 | 106,639,017 |
About Compound Interest Calculator
The Compound Interest Calculator computes the future value of an investment that grows through compound interest while receiving regular periodic deposits. It accepts five inputs: initial principal (the lump sum invested at the start), regular deposit amount (the amount added each compounding period), annual interest rate (as a percentage), investment period in years, and compounding frequency (Annually, Semi-annually, Quarterly, Monthly, or Daily — corresponding to n = 1, 2, 4, 12, or 365 periods per year). The calculator applies the standard compound interest with annuity formula: FV = P(1 + r/n)^(nt) + PMT × [(1 + r/n)^(nt) − 1] / (r/n).
Results are displayed in three summary cards — Final Amount, Total Contributed (principal plus all deposits), and Total Interest Earned — followed by a year-by-year amortization table. Each row in the table shows the cumulative amount contributed (initial principal plus deposits up to that year), the interest earned so far, and the total balance at year end. This table is especially valuable for visualizing the compounding effect: in early years most of the balance is contributions, but as years pass interest begins to dominate, illustrating why long investment horizons dramatically amplify returns.
This tool is designed for personal finance planning, retirement savings estimation, education fund projections, and investment strategy comparison. It is particularly useful for comparing how different compounding frequencies affect the final balance — for example, daily compounding yields slightly more than monthly compounding at the same annual rate. All calculations are performed locally in your browser using JavaScript arithmetic, with no data transmitted to any server. Both Korean and English interfaces are supported, with locale-aware number formatting.
Key Features
- Standard compound interest formula with regular deposits: FV = P(1+r/n)^nt + PMT[(1+r/n)^nt − 1]/(r/n)
- Five compounding frequencies: Annually (n=1), Semi-annually (n=2), Quarterly (n=4), Monthly (n=12), Daily (n=365)
- Year-by-year amortization table showing cumulative contributions, interest earned, and total balance per year
- Three summary cards: Final Amount, Total Contributed, and Total Interest Earned
- Investment period up to 50 years for long-term savings projections
- Locale-aware number formatting with comma-separated thousands for readability
- Real-time recalculation as any input changes — no submit button needed
- 100% client-side processing — your financial data never leaves your browser
Frequently Asked Questions
What formula does the compound interest calculator use?
The calculator uses the future value of a growing annuity formula: FV = P × (1 + r/n)^(n×t) + PMT × [(1 + r/n)^(n×t) − 1] / (r/n), where P is the initial principal, PMT is the regular deposit per compounding period, r is the annual interest rate (as a decimal), n is the number of compounding periods per year, and t is the number of years. This is the standard time-value-of-money formula used in financial mathematics.
What is the difference between annual and monthly compounding?
With annual compounding, interest is added once per year. With monthly compounding, interest is added 12 times per year, and each month's interest earns interest the following month. Monthly compounding yields a slightly higher final balance than annual compounding at the same nominal annual rate. The effective annual rate for monthly compounding at 6% is (1 + 0.06/12)^12 − 1 ≈ 6.168%, compared to exactly 6% for annual compounding.
How does the regular deposit affect the final balance?
Regular deposits use the annuity component of the formula and grow with compound interest just like the principal. Each deposit earns interest from the time it is made until the end of the investment period. The longer the investment period, the more powerful the effect of regular deposits — a monthly deposit started at year 1 has many more compounding cycles than one started at year 10, which is why starting early matters so much.
What inputs represent a typical savings account or retirement account?
For a bank savings account, use a rate of 2–4% with monthly compounding. For a stock market index fund for retirement, historical long-term returns in the range of 7–10% annually are commonly used (though not guaranteed). For a company 401(k) or Korean retirement pension, you might set the regular deposit to your monthly contribution and the rate to your expected fund return.
Can I use this calculator to see how much I need to save monthly for a goal?
The current tool solves for final amount given all inputs. To find the required monthly deposit for a target final amount, you would need to experiment by adjusting the deposit amount until the final amount matches your goal. A future version could directly solve for the deposit amount given a target FV.
Why does daily compounding give a higher return than monthly compounding?
More frequent compounding means interest is calculated and added to the principal more often. Each additional compounding event allows that interest to start earning its own interest sooner. The difference between monthly and daily compounding is small (a few basis points) but increases with higher interest rates and longer investment periods. At 7% annual rate over 30 years, daily compounding yields about 0.4% more final value than monthly compounding.
How accurate are the results for long-term projections?
The mathematics are precise — the formula is evaluated exactly using JavaScript floating-point arithmetic to the precision shown. However, long-term investment projections are inherently uncertain because real-world interest rates and investment returns fluctuate. The calculator assumes a constant, fixed annual rate throughout the entire investment period, which is a simplification. Use the results as directional guidance rather than precise financial forecasts.
Is the interest calculated on the total balance or just the principal?
Compound interest is calculated on the total accumulated balance — both the principal and all previously earned interest. This is what distinguishes compound interest from simple interest (which is calculated only on the original principal). The "total interest" in the results is the difference between the final balance and the total amount you contributed (principal plus all deposits).