Inflation Calculator
See what inflation quietly does to your money: what today's dollars will buy in the future, what future expenses will cost, and how much purchasing power a given rate destroys over time.
Written by Daniel Mercer, CFP® · Reviewed by Sarah Lindqvist, CFA
Last reviewed:
What $1,000 today buys in 20 years
$610
Purchasing power in today's dollars
- Cost of today's $1,000 basket then
- $1,639
- Purchasing power lost
- 39%
Purchasing power over time
What this calculator does
Inflation is the only financial force that affects every dollar you own, yet it never appears on a statement. This calculator makes it visible in both directions: what a sum of today’s money will actually buy after years of inflation (purchasing power), and what today’s expenses will cost in the future (the price of the same basket). The chart draws purchasing power decaying year by year — the picture most retirement plans are missing.
How the math works
Inflation compounds like interest, working against you:
Future cost = amount × (1 + i)ⁿ
Purchasing power = amount ÷ (1 + i)ⁿ
where i is the annual inflation rate and n the years. The two are mirror images: if prices double, each dollar buys half.
A worked example
$1,000 at 2.5% inflation over 20 years:
- Future cost of today’s $1,000 basket: 1,000 × 1.025²⁰ ≈ $1,639
- Purchasing power of $1,000 kept as cash: 1,000 ÷ 1.6386 ≈ $610
- Purchasing power lost: about 39%
Nothing dramatic happened in any single year — 2.5% is the Fed’s comfort zone — yet cash under the mattress lost more than a third of its value. Stretch the horizon to 30 years and the loss passes 52%. This is why “saving” and “investing” are different activities: savings preserve dollars, investments must preserve purchasing power.
Practical tips
- State long-term goals in today’s dollars, then inflate them. “I need $50,000 a year in retirement” is meaningful today. If retirement is 25 years out at 2.5% inflation, the nominal target is about $92,700 a year. Planning with the nominal number from the start prevents the classic halved-lifestyle surprise.
- Demand a real return from every account. An account yielding 1% during 3% inflation loses 2% of purchasing power annually with perfect safety. Compare every yield against current CPI — the CD calculator plus this page prices any “safe” return honestly.
- Revisit fixed payments with gratitude. Inflation cuts both ways: a fixed $1,896 mortgage payment gets easier every year as wages and prices rise around it. Long fixed-rate debt is one of the few household-level inflation hedges.
- Don’t over-rotate to the latest CPI print. Single-year spikes and dips are noise for multi-decade plans. Use a long-run average for planning and rebalance the assumption every few years, not every headline.
The third rail of every projection
Most of ToolGrym’s long-horizon tools let you set an inflation assumption — the retirement calculator deflates its projection into today’s dollars, and the FIRE calculator sidesteps the problem by using real (after-inflation) returns throughout. Whenever a projection spans more than a decade, the inflation input deserves as much attention as the return input; this page is where you build the intuition for what that number does.
Frequently asked questions
- What inflation rate should I use?
- US consumer prices have risen at roughly 2.5–3% per year averaged over recent decades, with painful exceptions (over 8% in 2022, near zero in 2015). The Federal Reserve explicitly targets 2% over the long run. For planning, 2.5–3% is the conventional band; run both ends to bracket your answer.
- Where does official inflation data come from?
- The Bureau of Labor Statistics publishes the Consumer Price Index (CPI) monthly, tracking a weighted basket of goods and services — housing, food, transportation, medical care, and more. When headlines say "inflation was 3.2% last year," they're quoting CPI. Your personal inflation rate differs based on what you actually buy: renters, drivers, and retirees experience different baskets.
- Why do small rates matter so much over long periods?
- Because inflation compounds, exactly like interest in reverse. At 2.5%, prices double roughly every 28 years (the rule of 72). A comfortable-sounding retirement income of $60,000 planned 30 years ahead buys about $28,600 of today's living — less than half. Any plan spanning decades that ignores inflation is quietly planning for half a lifestyle.
- How do I protect savings from inflation?
- Hold long-term money in assets whose returns historically outpace inflation — broad stock index funds have averaged roughly 7% after inflation over long horizons — and keep cash-like savings in accounts whose yield at least approaches the inflation rate. Treasury Inflation-Protected Securities (TIPS) and Series I savings bonds are explicitly indexed to CPI for the most direct protection.
- Is deflation good, then?
- Falling prices sound pleasant but are historically associated with economic contraction: consumers delay purchases, debt burdens grow in real terms, and wages fall. Central banks target low positive inflation (about 2%) precisely to keep a buffer above zero. For personal planning, the practical assumption is that prices rise slowly, forever.
Sources
Written by
Daniel is a Certified Financial Planner™ with 12 years of experience helping households manage debt, savings, and retirement planning. He writes ToolGrym’s calculator guides and explains the math behind every tool.
Reviewed by
Sarah is a CFA charterholder who reviews every ToolGrym calculator and article for mathematical accuracy. She has 10 years of experience in fixed-income analytics and consumer lending models.