Inflation Impact Calculator
See what your money will really be worth after inflation — starting from the live FRED CPI rate. Get your future buying power, the amount you'd need to keep pace, and how fast your cash halves.
At the current 3.7% CPI, $10,000 today buys just $4,835 in 20 years — and you'd need $20,681 to keep pace. Inflation is the tax nobody talks about.
3.7%
Live US CPI inflation, year-over-year (FRED, Q3 2026) — the calculator's default rate
$20,681
What you'd need in 20 years to match $10,000 today at 3.7% inflation
~19 yr
How long until your cash loses half its buying power at 3.7% inflation
What inflation is doing to your money right now
The invisible tax
Inflation doesn't announce itself — it slowly erodes the value of cash held in low-yield accounts. A $50,000 emergency fund earning 0.5% loses real purchasing power every year at 3%+ inflation.
Inflation and long-term planning
Retirement calculators that don't account for inflation dramatically understate the savings required. A $3,000/month budget today will need $5,400+/month in 20 years at just 3% inflation.
The Rule of 72
Divide 72 by the inflation rate to estimate how many years it takes to halve purchasing power. At the current 3.7%: about 19 years. At 7%: roughly 10 years. At 9.1% (the 2022 peak): under 8 years. The calculator shows the exact figure using logarithms.
The purchasing power formula
Formula
Future Buying Power = Amount ÷ (1 + r)^Years
Amount Needed Later = Amount × (1 + r)^Years (the mirror — keep pace)
Real Value Loss (%) = (1 − 1 ÷ (1 + r)^n) × 100
Years to Halve = ln(2) ÷ ln(1 + r)
Break-even Return = r (just to stand still)
Worked example — $10,000 at the live 3.7% CPI over 20 years:
Buying power = $4,835 · Lost = $5,165 (51.7%)
Needed to keep pace = $20,681 · Halves in ~19 yearsFuture buying power = today's amount ÷ (1 + inflation rate)ⁿ. With $10,000 today and inflation at the current 3.7% CPI, in 20 years that $10,000 only buys about $4,835 worth of goods — a 51.7% loss in real value. Flip the formula and you get the mirror: you'd need $20,681 in 20 years to buy what $10,000 buys now.
To maintain purchasing power, your money must grow faster than inflation. Any savings vehicle returning less than the inflation rate is losing real value every year — even if the nominal balance rises. The calculator defaults to the live FRED CPI rate so your starting point reflects today's economy.