Key takeaways
- At 3% inflation, $100 buys what $74 does today after 10 years, and $41 after 30.
- Cash loses purchasing power whenever its interest rate is below inflation. Money in a 0% checking account loses about half its value in 23 years.
- Your real return is roughly your return minus inflation. At 7% returns and 3% inflation, it’s about 3.883%.
- Keep short-term money safe but earning, and invest long-term money for growth that outpaces inflation.
Inflation is slow enough to ignore month to month and strong enough to reshape a retirement over decades. Understanding it changes two decisions: where you keep your cash, and how you plan for the future.
What inflation does to a dollar
Inflation is the general rise in prices, usually measured by the Consumer Price Index. When prices rise 3% a year, each dollar buys a little less every year, and the effect compounds:
| After | What $100 buys, in today’s dollars |
|---|---|
| 5 years | $86 |
| 10 years | $74 |
| 20 years | $55 |
| 30 years | $41 |
The Federal Reserve aims for 2% inflation over the long run, but actual inflation has run well above that at times, including the early 1980s and 2021–2023.
Nominal vs. real returns
The nominal return is what your statement shows. The real return is what’s left after inflation, meaning how much more you can actually buy.
The exact formula is (1 + return) ÷ (1 + inflation) − 1. A savings account paying 4% with 3% inflation has a real return of 0.971%. One paying 0.5% has a real return of -2.427%: the balance grows, but it buys less every year.
$10,000 over 20 years at 3% inflation
| Where it’s kept | Rate | Balance | In today’s dollars |
|---|---|---|---|
| Checking account | 0% | $10,000 | $5,537 |
| Traditional savings | 0.5% | $11,051 | $6,119 |
| High-yield savings | 4% | $22,226 | $12,306 |
| Stock-heavy portfolio (long-run average) | 7% | $40,387 | $22,362 |
The first two rows lose real value even though the balance never drops. The last row grows the most but isn’t guaranteed: stock returns swing widely from year to year, and a 20-year average can land well above or below 7%.
Matching the money to the job
The fix isn’t to invest everything. It’s to match each pile of money to when you’ll need it:
- Emergency fund and next 1–2 years of known expenses: insured high-yield savings or a money market fund. You accept a small real loss in exchange for safety and access.
- Goals 2–5 years away: CDs, Treasury bills, or short-term bond funds can lock in rates that roughly keep pace with inflation.
- Long-term money (retirement, 10+ years): a diversified mix of stocks and bonds. Stocks have historically outpaced inflation over long periods, though with real short-term risk.
- Inflation-protected options: I bonds and TIPS adjust with CPI, so they protect purchasing power directly.
Plan in today’s dollars
Inflation matters most for long-range goals. A retirement that needs $60,000 a year today will need about $145,636 a year in 30 years at 3% inflation. Two ways to handle it:
- Project in nominal dollars and inflate your spending target, as our retirement calculator does.
- Project in real dollars by using a real return (such as 4% instead of 7%) and keeping the target in today’s dollars.
Both give the same answer if done consistently. The mistake is mixing them, such as using a 7% nominal return against a target in today’s dollars, which overstates how prepared you are. For more on setting targets, see setting a realistic savings goal and how much do I need to retire?