Why money loses value

Prices creep up

Think of a shopping basket: bread, rice, cooking oil, a bus ticket, the electricity bill. If that basket cost $100 last year and costs $105 today, its price has risen by 5%. When prices rise like this across most of what people buy, it is called inflation.

Inflation is usually measured over a year and given as a percentage. In most countries, a government statistics office tracks the prices of a fixed basket of everyday goods and services and publishes how much more it costs than a year before. That figure is an average. Bread may get dearer faster than phones, and your own basket can differ from the official one.

A little inflation is normal in most economies, and many central banks try to keep it low and steady. What matters for you is that it rarely stops.

What money is really worth

A $100 note says $100 on it forever. What it can buy does not stay the same. That second thing — how many goods and services your money can actually buy — is its purchasing power, and it is the one that matters.

When prices rise, purchasing power falls. The money has not changed; the world around it has become more expensive.

Why cash under the mattress loses value

Money kept at home earns nothing. Each year inflation takes its full share of purchasing power from it, and nothing is added back. The example above is exactly what happens to cash left in a drawer for ten years.

Money in a bank deposit earns interest, which makes up for part of inflation, all of it, or sometimes more. Investing can make money grow faster still, but it carries risk. This is why the Foundations path starts here: doing nothing with money is not a safe choice, only a quiet one.

Change the rate and the number of years. A rate that sounds small takes a large bite when it runs for a long time.

Nominal and real return

When a bank says a deposit pays 8% a year, that 8% is the return in money: $1,000 becomes $1,080. This is the nominal return — the number on the statement.

What you care about is what the $1,080 can buy. If prices also rose 5% that year, most of the gain only kept up with prices. The real return is what is left after inflation: how much more you can actually buy.

A quick rule: real return ≈ nominal return − inflation. For an exact figure, divide instead of subtracting.

These rates are made up to show the arithmetic. Real interest rates and inflation differ between countries and between years, and both change.

What it means for an investor

Inflation sets the bar. An investment whose return does not beat inflation over time has lost purchasing power, even if its number went up. Keeping — and growing — what money can buy is one of the main reasons people invest at all.

That does not mean every investment beats inflation. Shares can fall and stay down for years. A bond with a fixed interest rate can be overtaken by inflation that rises after you bought it. Inflation is a risk to keep in mind, not a reason to take any risk at all.

In short

Inflation is the slow rise of prices, and it shrinks what your money can buy. Cash earns nothing and loses purchasing power every year; a deposit or an investment has to earn more than inflation just to stand still. Look at the real return — what you can buy — not only the number on the statement.