Annuity Payout Calculator
Work out the fixed amount you can draw from a lump sum over a chosen term, plus total payout and total interest.
輸入資料
計算結果
重點速覽：Annuity payout derives the fixed periodic withdrawal from a lump sum until principal and interest are exhausted (ordinary annuity, end-of-period): a = PV / [(1 - (1 + i)^-n) / i], where i = annual rate / payments per year and n = years x payments per year. Total payout = a x n; total interest = total payout - PV.
計算公式
每期利率 i = 年利率 ÷ 每年派發次數;總期數 n = 年期 × 每年派發次數。
每期派發 a = PV ÷ [(1 − (1 + i)⁻ⁿ) ÷ i]。
派發總額 = 每期派發 × n;總利息 = 派發總額 − 初始本金。
$$a = \dfrac{PV}{\dfrac{1 - (1 + i)^{-n}}{i}}$$$$i = \dfrac{\text{年利率}}{m}, \quad n = \text{年期} \times m$$使用說明
- Enter the initial principal.
- Enter the annual rate during the payout and the payout term.
- View the monthly payout, total payout and total interest earned.
本金 HK$100,000、每月派發時，不同年利率與年期對應的每月派發額
| 年利率 | 派發年期 | 每月派發額 | 派發總額 | 總利息 |
|---|---|---|---|---|
| 3% | 10 年 | HK$965.61 | HK$115,872.89 | HK$15,872.89 |
| 5% | 5 年 | HK$1,887.12 | HK$113,227.40 | HK$13,227.40 |
| 5% | 10 年 | HK$1,060.66 | HK$127,278.62 | HK$27,278.62 |
| 5% | 20 年 | HK$659.96 | HK$158,389.38 | HK$58,389.38 |
| 7% | 10 年 | HK$1,161.08 | HK$139,330.18 | HK$39,330.18 |
理財情境案例
案例一：100 萬本金每月可派多少
退休人士手上有本金 HK$100,000，希望在 10 年內每月領取固定金額直至用盡，假設本金年利率 5% (每月生息)。
每月派發 a = 100,000 ÷ [(1 − (1.004167)⁻¹²⁰) ÷ 0.004167] ≈ HK$1,060.66。10 年合共派發約 HK$127,279，其中約 HK$27,279 來自期間所賺利息。
案例二：拉長年期的取捨
同樣 HK$100,000、年利率 5%，若派發年期由 10 年延長到 20 年，每月派發降至約 HK$659.96 (少了近四成)，但因餘額生息更久，派發總額升至約 HK$158,389。
換言之，領得慢、每月少，但總領得多；領得快、每月多，但總領得少。規劃退休固定收入時，需在『每月現金流足夠生活』與『資金可維持多久』之間權衡。
常見問題
How much can HK$100,000 pay out a year?
It depends on the term and rate. At 5% annual, paid monthly over 10 years, about HK$1,061 a month. A longer term means a smaller monthly payout; a higher rate means more, because the unwithdrawn balance keeps earning.
Why is the total payout more than the principal?
Because the unwithdrawn balance keeps earning interest during the payout, and that interest is also paid out. So total payout = principal + interest earned.
How does this differ from an annuity accumulation?
Accumulation is the 'saving' phase — regular deposits grow to a future value; payout is the 'spending' phase — deriving the periodic withdrawal from a lump sum until it is used up. They are the two ends of an annuity's life.
How is annuity payout different from a perpetuity?
An annuity payout exhausts the principal over a fixed term (balance reaches zero). A perpetuity spends only the interest (withdrawal = principal x periodic rate) and keeps the principal forever. Higher payout if you exhaust it; perpetuity preserves capital but pays far less.
Will an actual insurance annuity match this?
Usually not exactly. This is a simplified model (fixed rate, no fees). Real annuities may have floating/non-guaranteed returns, charges, mortality-linked (lifetime) provisions and guarantees. Use this for concepts and estimates; rely on the policy illustration for actual figures.
相關工具
參考資料
內容審核：香港計算器財經團隊。計算邏輯與公式參考香港金融管理局（HKMA）及投資者及理財教育委員會（IFEC）之個人理財計算指引，結果僅供參考，實際以相關機構公佈為準。