Guide · Reviewed 6 September 2026
$100K in savings loses 30% purchasing power over 15 years at 3% inflation. Bonds + stocks protect against inflation; cash doesn't.
Inflation is the decline in purchasing power. At 3% annual inflation (historical average), prices double every 24 years. Cash in a savings account earning 0.1% loses real value. Stocks and real estate outpace inflation; bonds partially protect.
Real returns vs nominal returns
Nominal return: What your account shows (5% on a CD).
Real return: After inflation (5% − 3% inflation = 2% real return).
Example: Savings account at 0.1% with 3% inflation = −2.9% real return (losing 2.9% in purchasing power annually).
How inflation erodes $100K cash savings
| Year | Cash in account | Inflation 3%/year | Purchasing power | Loss |
|---|---|---|---|---|
| Year 0 | $100,000 | — | $100,000 | — |
| Year 5 | $100,000 | +15.9% | $86,261 | −$13,739 |
| Year 10 | $100,000 | +34.4% | $74,409 | −$25,591 |
| Year 15 | $100,000 | +55.8% | $64,186 | −$35,814 |
Asset class performance vs inflation
- Cash/savings (0%): Loses to inflation always. Real return: −3%/year.
- Bonds (3–4%): Barely keeps pace. Real return: 0–1%/year.
- Dividend stocks (2%): Plus capital growth. Real return: 4–5%/year.
- Index funds (7–8% historical): Handily beats inflation. Real return: 4–5%/year.
- Real estate (3% appreciation + 2% rent yield): Beats inflation. Plus leverage magnifies returns.
Bonds and inflation risk
Nominal bond return: 3% coupon.
At 2% inflation: Real return 1%. Good.
At 4% inflation: Real return −1%. Losing money in real terms.
During inflation spike: Existing bond prices fall (new bonds issued at higher rates). Long-duration bonds get hit hardest.
How to protect against inflation
- Diversify into stocks: Long-term real returns ~5% (beats inflation).
- Real estate/REITS: Leverage (5:1) + inflation hedge. Rents and prices rise with inflation.
- TIPS (Treasury Inflation-Protected Securities): Principal adjusts with CPI. Guaranteed real return ~1%.
- Commodities/precious metals: Volatile but historically track inflation.
- Avoid fixed long-term bonds in inflationary environment: Lock in low real returns.
Takeaway: Cash and low-yield bonds lose purchasing power over 10+ years. Stocks and real assets protect against inflation. Diversified portfolio (stocks + real estate + some bonds) maintains real wealth.