Inflation's real impact on your money
Key takeaways
04 · ideas- 3% inflation halves purchasing power in ~24 years
- Cash savings lose value every year in real terms
- Salary increases must beat inflation to be real raises
- Inflation affects different expense categories differently
Basic level
The essentials · 1 min
Inflation is the gradual rise in prices over time. At 3% annual inflation:
- $100 today → $74 in 10 years (in purchasing power)
- $100 today → $55 in 20 years
- $100 today → $41 in 30 years
This means money sitting in a savings account earning 0.5% interest is losing purchasing power every year when inflation runs at 3%+.
The practical impact: If your salary increases by 2% but inflation is 4%, your real income fell by 2%. You're earning more dollars but buying less.
Intermediate level
How it applies · 1 min
Inflation by expense category
Not all prices rise at the same rate. Historical averages (US, last 20 years):
| Category | Avg annual inflation |
|---|---|
| Healthcare | ~5–7% |
| College tuition | ~4–6% |
| Housing | ~3–5% |
| Food | ~2–4% |
| General CPI | ~2.5–3.5% |
| Technology | Negative (deflation) |
| Energy | Highly volatile |
Planning implication: If you're budgeting for retirement healthcare, use a 5–6% annual increase, not the general 3% inflation rate.
Real vs. nominal interest rates:- If your savings account pays 4% and inflation is 3%, your real return is ~1%
- If your mortgage rate is 7% and inflation is 4%, your real cost is ~3%
- High inflation partially "inflates away" fixed-rate mortgage debt — a benefit for homeowners
Inflation-beating investments: Historically, stocks have returned ~10% nominal (7% real), real estate ~8% nominal (5% real), and bonds ~4% nominal (1% real after inflation). Cash/savings under inflation is a guaranteed real loss.
Advanced level
The math, step by step · 1 min
The purchasing power formula
Where i = inflation rate, n = years.
At 3% inflation over 10 years: PV_{real} = 1 \cdot \frac{1}{(1.03)^{10}} = \0.744$
The Rule of 72 for inflation: Divide 72 by the inflation rate to find how many years to halve purchasing power.- 3% inflation → purchasing power halves in 24 years
- 6% inflation → purchasing power halves in 12 years
- 8% inflation → purchasing power halves in 9 years
Fisher equation: The relationship between nominal rates, real rates, and inflation:
Simplified: r_{real} \approx r_{nominal} - i
A 7% mortgage during 4% inflation has a real cost of only ~3% — while a 7% mortgage during 1% inflation has a real cost of ~6%. Same nominal rate, very different real burden.