Inflation-Adjusted Calculator
Find the future nominal amount and the loss of purchasing power from an amount, inflation rate and number of years.
輸入資料
計算結果
重點速覽：Future nominal = today's amount x (1 + inflation rate)^years. Purchasing-power loss% = [1 - 1/(1 + r)^years] x 100, the share of real purchasing power lost. Example: HK$1,000,000 at 2.5% for 20 years gives a future nominal of about HK$1,638,616 and a loss of about 39.0%. WARNING: The estimate assumes a constant rate; Hong Kong's long-run average inflation is about 2-3% but varies. Use a conservative rate for stress testing.
計算公式
未來名目 = 今日金額 × (1 + r)^n。
購買力縮水% = (1 − (1+r)^−n) × 100。
實質價值 = 未來名目 × (1+r)^−n = 今日金額。
使用說明
- Enter today's amount.
- Enter the expected annual inflation rate and the number of years.
- View the future nominal equivalent and the purchasing-power loss.
理財情境案例
100 萬、通脹 2.5%、20 年
未來名目 = 1,000,000 × 1.025^20 ≈ 1,638,616。
購買力縮水 = (1 − 1.025^−20) × 100 ≈ 39.0%。
即 20 年後要 164 萬才等同今日 100 萬購買力。
常見問題
What is the difference between nominal and real value?
Nominal is the face amount (how much money you need in the future); real is the purchasing power after removing inflation (here it stays equal to today's amount). Plan savings goals in nominal terms, but judge adequacy in real terms.
What is Hong Kong's inflation rate roughly?
The long-run average is about 2-3%, but individual years swing widely (pandemics, rents, prices). The tool uses your input; a conservative value such as 3% is sensible for stress testing.
Why compound rather than simple interest?
Inflation erodes purchasing power continuously — after a rise, the base is higher, so compounding better reflects reality. Over long periods the gap between compound and simple is significant.
How does this relate to investment returns?
Nominal investment return minus inflation is the real return. For example, 8% nominal with 3% inflation gives a real return of about (1.08/1.03) - 1 = 4.85%. Use the two tools together to assess true profit.
How do I use this for retirement planning?
First compute the nominal monthly spending you will need at retirement (with this tool), then use a retirement calculator for the required capital. Inflation is retirement's hidden enemy — always include it.
相關工具
參考資料
內容審核：香港計算器科學團隊。通脹複利公式驗證。