Inflation Calculator

Q: How much does inflation reduce my money's value?

At 3% annual inflation, $100 of today's purchasing power falls to about $74 in 10 years, $55 in 20 years, and $41 in 30 years. Even 'low' inflation halves purchasing power roughly every 23 years.

Q: What is the average inflation rate?

U.S. CPI inflation has averaged roughly 3% per year over the last century, with long stretches near 2% and occasional spikes far higher. 2.5%-3% is the standard assumption for long-term planning.

Q: How do I protect savings from inflation?

Hold cash only for near-term needs, and put long-term money in assets whose returns have historically outpaced inflation — diversified stocks, inflation-protected bonds (TIPS and I-Bonds), and real assets. A savings account earning less than inflation is losing purchasing power every year.

The quiet tax on cash: see what today's dollars will buy in the future — or what a past amount would need to be today — at any inflation rate.

Buying power in the future

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Purchasing power lost

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Price level change

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Halving time at this rate

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The inflation formulas

Future buying power = Amount ÷ (1 + inflation)^years
Today's equivalent of past money = Amount × (1 + inflation)^years

Worked example

$10,000 held as cash for 20 years at 3% inflation:

Buying power = 10,000 ÷ 1.03²⁰ = 10,000 ÷ 1.806 = $5,537 — cash quietly loses almost half its value.

What 3% inflation does over a lifetime

Years	$100 buys the equivalent of…	Prices have risen…
10	$74	+34%
20	$55	+81%
30	$41	+143%
40	$31	+226%

This is why every long-term plan must be inflation-aware: a retirement target set in today's dollars needs to roughly double for a retirement 25 years away, wage negotiations below inflation are pay cuts, and "safe" cash savings earning less than inflation are guaranteed real losses. The defense is owning things that reprice with inflation — equities, TIPS, I-Bonds, real assets — for money you won't need soon. See real vs. nominal comparisons in the investment calculator.

Frequently asked questions

How much does inflation reduce my money's value?

At 3%: $100 → $74 of buying power in 10 years, $55 in 20, $41 in 30.

What is the average inflation rate?

Roughly 3%/yr in the U.S. over the past century; 2.5–3% is the standard planning assumption.

How do I protect savings from inflation?

Cash for near-term needs only; long-term money in assets that historically outpace inflation (stocks, TIPS, I-Bonds, real assets).

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Note: Uses a constant assumed rate rather than historical CPI data; actual inflation varies year to year. Not financial advice. Last reviewed: July 2026.