How Inflation Erodes Your Wealth

Inflation is the sustained rise in the prices of goods and services. At 2% annual inflation, something that costs 100 man-yen today will cost roughly 102 man-yen next year. In other words, the real purchasing power of 100 man-yen in cash steadily shrinks every year.

For practical strategies, books on inflation-proof investment strategies can show you how to protect your assets against rising prices.

Japan experienced prolonged deflation for many years, but since 2022 the inflation rate has risen to the 2-4% range. According to the Ministry of Internal Affairs and Communications' Consumer Price Index (CPI), the year-over-year increase was approximately 3.2% in 2023 and remained around 2% in 2024. The era when "holding cash is safe" is coming to an end.

Nominal Returns vs. Real Returns

The nominal return is the face-value yield on your investment. If you earn 5% on your portfolio, your nominal return is 5%. The real return, however, is the nominal return minus the inflation rate, representing the actual increase in your purchasing power.

The simplified formula is: Real return = Nominal return - Inflation rate. The precise formula is (1 + nominal return) / (1 + inflation rate) - 1. For example, with a 5% nominal return and 2% inflation, the real return is approximately 2.94%.

Real Returns at Different Inflation Rates

Let's evaluate a 5% nominal return investment under different inflation scenarios.

  • 0% inflation: Real return 5.00% - When prices are stable as in Japan's deflationary era, the nominal return directly translates to real wealth growth.
  • 1% inflation: Real return 3.96% - Even mild inflation reduces your purchasing-power-adjusted assets by roughly 18% compared to the nominal figure over 20 years.
  • 2% inflation: Real return 2.94% - If the Bank of Japan's 2% inflation target is met, a nominal 5% return effectively delivers only about 3% real growth.
  • 3% inflation: Real return 1.94% - At recent Japanese inflation levels, even a nominal 5% return yields a real return below 2%.
  • 5% inflation: Real return 0.00% - When the nominal return equals the inflation rate, your purchasing power neither grows nor shrinks.

Strategies to Protect Your Wealth Against Inflation

To preserve your assets in an inflationary environment, you need to earn returns that at least exceed the inflation rate. Here are concrete approaches.

  • Diversified equity investing: Companies can pass inflation through to product prices, making stocks a historically inflation-resistant asset class. Global equity indices have averaged roughly 7% annual returns over the past 30 years, well above inflation.
  • Real estate and REITs: Property values and rents tend to rise with inflation, providing a natural inflation hedge.
  • Inflation-linked government bonds: The principal adjusts with the inflation rate, guaranteeing a real return as a safe asset.
  • Reassess your cash allocation: After securing an emergency fund covering 6 to 12 months of living expenses, invest surplus cash to prevent inflation from eroding its value.

Our simulator lets you check your after-tax real returns. By entering a return rate that subtracts your assumed inflation rate, you can simulate your future assets on a purchasing-power basis.

Books on real returns and asset management will equip you to make investment decisions that account for the gap between nominal and real returns.