How Purchasing Power Changes: Inflation Over Time

In 1970, a gallon of gas cost $0.36, a movie ticket was $1.55, and the median home price was $23,000. Today those same things cost $3.60, $11, and $420,000. The stuff didn't get more valuable — the dollar got less powerful. That erosion is inflation, and understanding it changes how you think about saving, investing, and spending.

What inflation actually measures

Inflation is tracked through the Consumer Price Index (CPI), maintained by the Bureau of Labor Statistics. CPI measures the average price change of a “basket” of about 80,000 goods and services — food, housing, transportation, medical care, clothing, and more — weighted by how much a typical household spends on each.

When we say “inflation was 3.4% in 2023,” it means the CPI basket cost 3.4% more than it did in 2022. Individual items vary wildly: eggs might jump 30% while TV prices drop 10%.

Purchasing power across decades

$100 in 1970 had the same buying power as roughly $793 today. Flip that around: $100 today buys what $12.61 bought in 1970. The erosion is relentless, even in “low inflation” decades.

Hyperinflation: when the system breaks

Normal inflation is 2–4% per year. Hyperinflation is when it spirals out of control:

• Weimar Germany (1923) — Prices doubled every 3.7 days. A loaf of bread that cost 250 marks in January cost 200 billion marks by November.
• Zimbabwe (2008) — Monthly inflation hit 79.6 billion percent. The government printed 100-trillion-dollar bills that were worth less than the paper.
• Venezuela (2018) — Annual inflation exceeded 1,000,000%. Workers carried backpacks of cash to buy groceries.

Hyperinflation is always caused by the same thing: governments printing money far faster than the economy produces goods.

Why central banks target 2%

Zero inflation sounds ideal, but economists fear deflation (falling prices) even more. When prices drop, consumers delay purchases (“why buy today if it's cheaper tomorrow?”), businesses earn less, wages fall, and the economy spirals downward. Japan experienced this “lost decade” of stagnation from the 1990s onward.

The 2% target provides a buffer against deflation while keeping erosion manageable. At 2%, prices double roughly every 36 years — slow enough that wages and investments can keep pace.

Real vs nominal returns

Real return = Nominal return - Inflation rate

Example:
  Your savings account pays 5.0% (nominal)
  Inflation is 3.4%
  Real return = 5.0% - 3.4% = 1.6%

  Your money grows, but only 1.6% in actual
  purchasing power.

A stock market return of 10% in a year with 3% inflation is really a 7% gain in purchasing power. A savings account paying 2% during 3% inflation means you're losing buying power despite watching your balance grow.

Inflation is invisible until you zoom out. A dollar today is worth less than yesterday and more than tomorrow. The question isn't whether your money will lose value — it's whether your investments outpace the erosion.