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How Inflation Erodes Wealth
Inflation measures how much the price level rises across the economy, typically expressed as a percentage per year. When inflation is 3%, something that cost $100 today costs $103 next year. Your dollar buys less.
The insidious part: the effect compounds. Three percent annual inflation for 25 years means prices have more than doubled. Your savings account earning 1.5% interest is actually losing purchasing power every year.
Real Return: The Number That Matters
Nominal return is what your statement shows. Real return is what matters — it accounts for inflation:
Real Return ≈ Nominal Return − Inflation Rate
(More precisely: Real Return = (1 + Nominal) / (1 + Inflation) − 1, but the approximation works well for moderate rates.)
| Investment | Nominal Return | Inflation (3%) | Real Return |
|---|---|---|---|
| Savings account | 1.5% | 3% | −1.5% |
| US Treasury bond (5yr) | 4.0% | 3% | +1.0% |
| Bond index fund | 4.5% | 3% | +1.5% |
| Stock index (S&P 500 avg) | 10% | 3% | +7.0% |
| Real estate (avg) | 7% | 3% | +4.0% |
| Gold (long-run avg) | 3–4% | 3% | 0–1% |
Rule of 72: How Fast Inflation Halves You
The Rule of 72 tells you approximately how many years it takes for inflation to cut your purchasing power in half: Years = 72 ÷ Inflation Rate
| Inflation Rate | Years to Halve Purchasing Power | Example: $100k becomes worth... |
|---|---|---|
| 2% | 36 years | $50k in purchasing power |
| 3% | 24 years | $50k in 24 years |
| 5% | 14 years | $50k in 14 years |
| 7% | 10 years | $50k in 10 years |
| 10% | 7 years | $50k in 7 years (hyperinflation) |
Best Inflation Hedges
1. Equities (Stocks)
Over long periods (10+ years), stocks are the strongest inflation hedge. Companies can raise prices, and profits tend to grow with inflation. The S&P 500 has delivered ~7% real returns per year over 100 years — the best of any major asset class.
2. Real Estate
Property values and rental income both tend to rise with inflation. Real estate provides two inflation hedges: property appreciation and rising rental yields. With mortgage debt, you're also repaying fixed debt with inflated future dollars.
3. TIPS (Treasury Inflation-Protected Securities)
US government bonds where the principal adjusts with CPI. If inflation is 4%, a $10,000 TIPS becomes $10,400. You're guaranteed a real (inflation-adjusted) return set at auction. The safest inflation hedge but with lower upside.
4. I-Bonds
US savings bonds earning a combination of a fixed rate plus the CPI inflation rate. Limited to $10,000/year per person. Zero risk of nominal loss. Often the best risk-adjusted inflation hedge available to individual investors.
5. Commodities
Oil, metals, agricultural products — their prices often directly drive inflation readings. Commodity indexes historically provide strong inflation correlation but high volatility and no yield.
Historical Asset Performance vs Inflation
| Asset Class | Nominal Return (100yr avg) | Real Return (after ~3% inflation) | Inflation Protection |
|---|---|---|---|
| US Stocks (S&P 500) | ~10% | ~7% | Excellent |
| US Real Estate | ~7% | ~4% | Very Good |
| Corporate Bonds | ~5% | ~2% | Moderate |
| Gold | ~3–4% | ~0–1% | Moderate (inflation parity) |
| Cash / Savings | ~1.5–2% | ~−1.5% | Poor |
| Long-Term Bonds | ~4% | ~1% | Poor (hurt by rising rates) |