How Inflation Changes What a Dollar Buys

The VividTimeline TeamJuly 2, 20263 min read

InflationPurchasing powerCost of livingHow money works

Inflation is the slow rise in the general price of things over time. The dollar in your pocket keeps its number, but the amount it can buy drifts downward. This post explains what that means and shows the math with a picture.

The short version: inflation does not shrink your dollars. It shrinks what they buy.

Amount versus purchasing power

A 100 dollar bill is always 100 dollars. What changes is its purchasing power: how much real stuff it trades for. When prices rise 3 percent in a year, a basket of goods that cost 100 dollars now costs 103 dollars, so the same 100 dollar bill covers a little less of it than it did a year earlier.

Stretch that over decades and the drift becomes large:

At 3% inflation, the buying power of $100 falls to about $41 over 30 years.

Why it adds up so fast

Each year prices rise a little, so each year your dollar buys a little less, and that shrinking compounds on itself. At 3 percent, prices roughly double about every 24 years (the rule of 72, in reverse). Over 30 years prices grow about two and a half times over, so 100 dollars ends up buying only about what 41 dollars buys today. The bill still reads 100 dollars; its reach is what fell.

It is compound growth pointed the other way: growth builds a balance up year after year, and inflation wears buying power down year after year (see How Compound Growth Works).

Why it matters for money that just sits

Cash that earns nothing does not lose any dollars, but it quietly loses purchasing power at the inflation rate every year. Money that grows faster than inflation gains real ground; money that grows slower than inflation loses real ground even as its dollar balance rises. The gap between your growth rate and the inflation rate is what determines whether you are ahead or behind in real terms.

Seeing it on your own timeline

Whether a given plan keeps pace with inflation depends on your own rates and time horizon. VividTimeline lets you set an inflation assumption and view balances in both nominal dollars and today's buying power, so the numbers on the screen reflect what they would actually buy.