What is GDP?

When the news says the economy "grew 2% last quarter," that’s GDP. It’s the closest thing economics has to a single vital sign — and understanding what goes into it tells you a surprising amount about how economies actually work.

What GDP measures

GDP is the total monetary value of everything produced within a country over a period. The most intuitive way to build it up is the expenditure approach, which adds up everyone’s spending:

• C — Consumption: household spending on goods and services. The biggest slice, around 70% in developed economies.
• I — Investment: businesses building capacity — factories, equipment, construction. (Note: this means physical investment, not buying stocks.)
• G — Government spending: public spending on goods and services (but not benefits and pensions, which are just transfers).
• X − M — Net exports: exports minus imports. A surplus adds to GDP; a deficit subtracts.

Add them together — C + I + G + (X − M) — and you have the size of the economy.

Real vs nominal GDP

Here’s the distinction that matters most. Nominal GDP measures output in today’s prices. The problem: if both production and prices rose 5%, nominal GDP jumps 10% — but people aren’t actually 10% better off. Real GDP strips out price changes to isolate true growth in the volume of stuff produced. This is why growth is almost always quoted in "real terms": a country with 10% nominal growth but 8% inflation has really only grown 2%.

GDP per capita: living standards

Total GDP tells you how big an economy is, not how well its people live. For that, divide by population to get GDP per capita. A country whose GDP grows 10% while its population also grows 10% has seen no improvement per person at all. Per-capita figures are what let you compare living standards across countries fairly.

Leading and lagging indicators

GDP itself is reported with a lag, so markets watch faster signals to anticipate it. Leading indicators — like business surveys (the PMI), the yield curve, and consumer confidence — tend to move before the economy turns, which makes them useful for forecasting. Lagging indicators — like the unemployment rate — confirm a trend only after it’s underway. Reading the leading ones is how investors try to see a slowdown coming.