Inflation & Purchasing Power Calculator
Calculate future cost of living, cash purchasing power erosion, and inflation-adjusted real returns over 5 to 30 year horizons.
Your $100,000 cash will lose 25.6% of its purchasing power in 10 years at 3.0% annual inflation.
Purchasing Power Erosion Over Time
| Year Milestone | Future Cost for Same Goods | Remaining Real Buying Power | Cumulative Loss |
|---|
About this tool
How to use it
- Enter your starting cash or investment savings principal (e.g. $100,000).
- Choose your planning horizon in years (e.g. 10 years for medium-term goals or 25 years for retirement).
- Specify your anticipated annual inflation rate (historical US/UK average is ~3.0%) and your investment return rate.
- Click Calculate Purchasing Power to see future cost of living, real value in today's dollars, and decade milestone decay.
Why it matters
Inflation quietly erodes the real purchasing power of uninvested capital. Even at a modest 3% annual inflation rate, $100,000 left in cash loses more than 25% of its real buying power in 10 years and over 50% in 24 years. Calculating real (inflation-adjusted) returns is essential for preserving wealth.
When to use it
Use this calculator when planning retirement withdrawal rates, evaluating whether high-yield savings accounts beat inflation, deciding between cash allocations and index funds, or projecting future child tuition expenses.
Good to know
Calculations utilize the classical Fisher equation: `(1 + Nominal Return) = (1 + Real Return) × (1 + Inflation Rate)`. Consumer price indices (CPI) measure average consumer baskets; personal inflation rates may vary depending on housing, healthcare, and education costs.
Common questions
What is the historical average inflation rate?
Over the past 50 to 100 years, the US Consumer Price Index (CPI) has averaged approximately 3.0% to 3.2% annually, with periods of lower inflation (~1.5% in the 2010s) and sharp spikes (over 8% in 2021–2022).
What is the 'Rule of 72' for inflation?
The Rule of 72 estimates how long it takes for prices to double (or purchasing power to be cut in half). Divide 72 by the annual inflation rate: at 3% inflation, prices double in 24 years (72 / 3 = 24).
Does a 5% HYSA account beat 3% inflation?
Yes, but remember taxes. A 5% yield against 3% inflation produces a nominal 2% spread. However, if your marginal income tax bracket is 25%, taxes consume 1.25% of the yield, leaving an after-tax return of 3.75% and a real net gain of approximately +0.75%.
What assets protect best against long-term inflation?
Historically, diversified equities (stock index funds), real estate, Treasury Inflation-Protected Securities (TIPS), and businesses with strong pricing power have consistently outpaced long-term inflation, unlike fixed cash.