What Is Inflation?
Inflation is the rate at which money loses purchasing power, so a return below it is a loss in real terms even when the number in the account goes up. It compounds, it damages cash most reliably, and it makes every long-run nominal chart flatter than it looks.
Every other cost in finance is charged to you. This one is charged to the ruler you measure with, which is why an account can grow every single year and still be worth less at the end.
How it works
Prices rising and money weakening are the same event described from two sides. If a basket of goods costs 3% more this year, then the pound in your hand buys 3% less. Nothing was taken from the account — the thing the account is denominated in got smaller.
So there are two versions of every return. The nominal one is what the statement says. The real one is what is left after inflation, and it is the only one that describes whether you can buy more than you could before.
Every long-run chart you have ever seen is nominal unless it says otherwise. A line rising steadily over thirty years is partly the asset doing well and partly the unit shrinking, and the two are not separated for you.
A worked example
Inflation is a fee, and it can be priced like one. A 3% inflation rate applied to cash is arithmetically identical to a fund charging 300 basis points a year — deducted annually, compounding, charged whether or not anything went well.
Put that next to this site’s own fee measurement. Over thirty years, an annual charge of 5 basis points costs 1.5% of the final balance, 20 basis points costs 5.8%, 75 costs 20.2%, and 150 costs 36.5%.
Inflation at 3% is double the largest of those. No retail fund in the world charges 300 basis points, and the cost of holding cash through ordinary inflation exceeds it — silently, with no statement, and with no line item anyone can point to.
That is why cash is not the neutral position it feels like. It is the one asset whose nominal value cannot fall and whose real value falls every year by exactly the inflation rate. The safety is in the number, not in what the number buys.
And it compounds. Three percent for one year is a rounding error. Three percent for thirty years leaves purchasing power at about 41% of where it started — the money did not move and well over half of it is gone.
And the compounding runs against a target that is also moving. A savings goal stated as a fixed sum is quietly a smaller goal every year it is not met. Stating it in today’s money and revising it upward with prices is the only version that means the same thing at the end as it did at the start, and almost nobody does it — which is how a plan can be met to the letter and still fall short of what it was for.
What it does to a drawdown
A flat year during inflation is a losing year, and a losing year is worse than it appears. On this site’s shared series the deepest drawdown ran 3.76% and the longest wait for a new high was 73 bars — all measured nominally. In real terms the hole is deeper and the wait is longer, because the level you are trying to get back to has moved up while you were below it.
Recovering to the old number is not recovering. The old number buys less than it did.
The original data
This site’s thirty-year fee measurement: 5 basis points costs 1.5% of the final balance, 20 costs 5.8%, 75 costs 20.2%, 150 costs 36.5%.
Inflation runs the identical arithmetic at a much larger number. Three percent is 300 basis points — twice the largest fee measured, charged to everyone, on every unit of currency held, every year.
One honest caveat: it is a measurement, not an observation. Nobody sees inflation; a statistical agency estimates it from a basket of goods, and the basket is an average across a whole population.
Your own rate is different from the published one and there is no way to know by how much. If your spending is weighted toward things rising faster than the average, the headline figure understates what is happening to you.
When it fails
The characteristic failure is judging a long-run result in nominal terms. An account that doubled over twenty years sounds like a success and may be close to flat once the unit is held constant. The number went up, the comparison was never made, and the strategy that produced it gets credited with a result it did not achieve. The fix is unglamorous: every long-horizon figure has to be stated in real terms or it is not a claim about purchasing power at all.
A second failure is assuming assets automatically keep pace. Some do over long periods and none do reliably over short ones, and “inflation hedge” is a claim that needs evidence rather than a category.
A third is treating cash as the option with no downside. It carries no price risk and a certain real cost, which is a trade-off rather than an absence of risk.
A fourth is comparing today’s price to an old one without adjusting, which makes every historical level look cheap.
And a fifth is forgetting that the published figure is not yours. It is an average over a basket somebody else assembled, and your own spending is the only rate that decides whether you are better off.
Related
Interest rate covers what money earns, which is the other half of the real return. Risk management covers sizing against a target that moves every year. And expectancy covers measuring an edge once every cost is counted.
The thing that took me longest to internalise is that a savings account paying nothing is not a neutral choice. It is a position, it has a cost, and the cost is charged annually and compounds. Nobody sends you a statement for it, which is exactly why it is the easiest cost in finance to ignore for a decade at a time.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money.