Compound Interest Future Value (FV) Calculator
From principal, annual rate, years and compounding frequency, compute the future value and total interest, with a year-by-year breakdown.
輸入資料
計算結果
重點速覽：FV = P x (1 + r/n)^(n·t), r = annual rate, n = compounds per year, t = years; total interest = FV - P. More frequent compounding lifts FV slightly (limit = continuous). Example: HK$100k at 6% monthly, 20y → FV ≈ HK$331,021, interest ≈ HK$231,021. WARNING: Assumed fixed return only; actual returns vary and are not guaranteed; inflation and fees reduce real return. Education, not advice.
計算公式
期利率 = 年利率 ÷ 每年複利次數。
總期數 = 年數 × 每年複利次數。
FV = 本金 × (1 + 期利率)^總期數；總利息 = FV − 本金。
使用說明
- Enter the principal.
- Enter the annual rate and years.
- Enter the compounding frequency (1/4/12).
- View the future value and total interest.
理財情境案例
10 萬存 20 年、年息 6% 月複利
期利率 = 6% ÷ 12 = 0.5%，總期數 = 240。
FV = 100,000 × 1.005^240 ≈ $331,021。
總利息 ≈ $231,021（本金的 2.3 倍）。
常見問題
What is the difference between compound and simple interest?
Simple interest is charged only on the principal; compound interest is charged on principal plus accumulated interest ('interest on interest'). Over time, compounding grows much faster — the core advantage of long-term investing.
Does compounding frequency matter much?
At the same nominal rate, more frequent compounding gives a slightly higher FV (monthly > quarterly > annual), but usually by under 0.1%-0.5%. The limit is continuous compounding e^(rt).
Can this handle monthly contributions?
No — this tool is for a single lump sum. For regular monthly investing (DCA / MP), use an annuity-FV formula or a recurring-investment calculator; that result is higher because each contribution compounds on its own.
Is the return guaranteed?
No. Investing involves risk and actual annual returns fluctuate. This is an estimate under a fixed assumed rate, not a guaranteed yield. Past performance is no guarantee of future results.
How does inflation affect this?
The nominal FV does not deduct inflation. At 2% inflation, real purchasing power ≈ FV / (1.02)^years. Pair with a retirement calculator's 'today's purchasing power' view to assess real gain.
Why might my bank's numbers differ?
Differences can come from compounding frequency, fee/tax deductions, rate assumptions, or a 365-day convention. This tool uses the standard mathematical compounding model for reference comparison.
相關工具
參考資料
內容審核：香港計算器科學團隊。複利終值公式驗證。