Inflation / Purchasing Power Calculator
Enter today's amount, an expected annual inflation rate and a time horizon to see what your money will buy in real terms — and the nominal amount you'd need in the future to keep the same purchasing power. Useful for retirement planning, long-term savings targets, and getting a feel for how much real value cash loses over decades.
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Future purchasing power
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Amount needed to keep same buying power
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Cumulative inflation
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Purchasing power lost (in today's $)
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Standard formula: future real value = amount ÷ (1 + annual rate)^years. Real-world inflation drifts year to year — Hong Kong's Composite CPI is published monthly by the Census and Statistics Department.
Formula
Future real value = amount ÷ (1 + annual rate)^years Nominal amount to keep same buying power = amount × (1 + annual rate)^years Cumulative inflation = (1 + annual rate)^years − 1
- · Compounded inflation is used — three years at 3% means cumulative inflation of (1.03)³ − 1 ≈ 9.27%, not a flat 9%.
- · The rate you enter is treated as a constant annual average; real CPI moves year to year, so use a long-run average as your baseline (Hong Kong's composite CPI has averaged roughly 2–3% per year over the last 10–20 years).
- · Hong Kong's Composite Consumer Price Index is published monthly by the Census and Statistics Department and is the official headline inflation measure for the city.
- · Results are pre-tax and ignore fees, and they assume your personal consumption basket tracks headline CPI — rent, education and medical costs often run hotter than the headline number.
- · Negative rates (deflation) are allowed; in that case future purchasing power increases.
- · Difference from the CAGR calculator: CAGR measures asset growth, while this tool measures the erosion of purchasing power. The maths is the same exponent, but the framing and unit differ.
Frequently asked
What inflation rate should I assume?
For a Hong Kong household, 2–3% is a sensible long-run assumption — the Composite CPI from the Census and Statistics Department has averaged roughly 2% over the last decade (with year-to-year swings). If your spending leans towards rent, private healthcare or education, add another 0.5–1% because those components typically run hotter than headline CPI. Internationally, the US long-run average is around 2–3% and most developed-market central banks target 2%. For retirement planning, run three scenarios — 2%, 3% and 4% — to see how sensitive your plan is to the assumption.
How does inflation relate to interest rates and real returns?
A rough rule of thumb is: real return ≈ nominal return − inflation rate (Fisher approximation); the exact Fisher equation is (1 + nominal) ÷ (1 + inflation) − 1. A 4% time deposit with 3% inflation has a real return of about 1% (4% − 3%) or more precisely 0.97%. To judge whether an investment is 'beating inflation' you should compare the real return, not the nominal headline. Hong Kong's Silver and Green Bonds are explicitly inflation-linked (with a floor rate) and are designed for this hedging use case.
Are there past periods when Hong Kong inflation was unusually high?
Yes. From the late 1980s through 1997, Hong Kong saw sustained inflation of 8–10% (occasionally double-digit), driven by the Linked Exchange Rate regime and a hot property market. In 2003–2004 there was outright deflation (CPI around −2%) following SARS and the post-Asian-crisis adjustment. After the 2008 global financial crisis and again pre-COVID, CPI swung quite a bit. The 'long-run average' blends those periods — 2–3% is a reasonable planning baseline, but expect any single year to deviate significantly.
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