Inflation 101

The other half of the government debt story.

What inflation actually is

Inflation is the expansion of the quantity of money and credit. Rising asset values, and later consumer prices, are a consequence of that expansion — a symptom of how much new money and credit entered the system, and how fast. Asset prices tend to move first, since new money typically flows into stocks, real estate, and other assets before it works its way into everyday spending. The rise in consumer prices — what CPI actually measures — follows with a lag (inflation lag) of roughly 14 months. That lagging price rise is what most people mean when they say "inflation," but it's really the tail end of a process that started earlier, in the money supply itself.

Not every price increase is monetary inflation in this sense. Supply disruptions, tariffs, or a bad harvest can push individual prices up for reasons that have nothing to do with money creation — but these tend to be short-lived and show up as one-off monthly outliers rather than a sustained broad rise across the whole basket.

How it's actually measured

The headline number you see in the news — CPI, the Consumer Price Index — comes from tracking the price of a fixed "basket" of goods and services that a typical household buys: groceries, rent, gasoline, health care, and so on. Statisticians price that same basket every month and compare it to the prior period. The percentage change is the inflation rate. "Core CPI" is the same idea with food and energy prices stripped out, since those two categories swing sharply for reasons that have nothing to do with broader inflation trends.

Why inflation and government debt are connected

Governments that borrow heavily have a strong incentive to lean on money and credit expansion, since that's how debt gets inflated away in real terms — a $30 trillion debt is a much lighter burden once it's being repaid in dollars worth less than the ones originally borrowed. CPI matters for the same underlying reason bond auction results matter: it's a measure of how much room the government still has to use that mechanism. The higher CPI runs, the less able the government is to keep leaning on it without consequences. Non-asset holders — people whose income and savings aren't tied to appreciating assets — bear the brunt of rising prices without offsetting gains, which at extreme levels risks real social and political strife. Foreign buyers of that government's bonds respond differently: they demand a higher yield to compensate for the currency devaluation they now expect over the life of the bond — which shows up directly on the Bond Auctions and yield curve pages.

Breakeven inflation — the market's own forecast

One of the more useful numbers on the Feeds pages is "breakeven inflation." It's derived from comparing regular Treasury bond yields to inflation-protected Treasury bond yields (TIPS). The gap between the two is, roughly, what bond investors collectively expect inflation to average over that bond's life. It's not a perfect forecast, but it reflects real money being bet on the outcome, which makes it one of the more credible inflation forecasts available.

CPI is more predictable than you'd think

Compared to forecasting interest rates or the demand for money — both notoriously hard to predict — CPI a year or more out is comparatively straightforward to estimate using quantity-of-money calculations, since they rely on essentially one variable: the growth rate of the money supply itself. That's a large part of why this site tracks money-supply-adjacent data alongside CPI directly, rather than treating CPI as a number that arrives unpredictably each month.

Why this affects you directly

• Wages that don't keep pace with inflation mean falling real purchasing power, even if the number on your paycheck is going up.
• Savings held in cash lose value in real terms during inflationary periods, which is part of why people look to assets like gold or other stores of value as a hedge.
• Interest rates set by central banks (see Central Banking) are adjusted largely in response to inflation, which in turn affects mortgage rates, credit card rates, and loan costs across the economy. The market also sets these rates and considers inflation.

See also: the Glossary for quick definitions, and What Debt Means for You for how this all lands on your household budget specifically.