Gross Domestic Product

Something is constantly being produced in a country: cars, bread, software, haircuts, doctor’s visits. Gross domestic product adds up what all these newly created goods and services are worth in a year. It is calculated in euros, so that one can even add together a loaf of bread and a train journey. The word “new” is important: anyone who resells a used bicycle does not increase gross domestic product, because the bicycle was already built earlier. Likewise, only what is created within the country’s borders counts. A German factory in Poland therefore increases Poland’s GDP, not Germany’s.

Why governments and stock markets stare at this one number

GDP is something like the fever thermometer of an economy. When it rises, more is being produced, there is usually more work and higher wages. When it shrinks, people lose their jobs and companies cut investments. If GDP falls for two consecutive quarters, experts speak of a recession, meaning a longer downturn.

Concrete decisions depend on this number. Central banks consider growth when deciding whether to raise or lower interest rates. Governments use it to plan their spending, since tax revenues grow roughly in step with the economy. Debt, too, is almost always stated in relation to GDP, because a billion means something completely different for a large country than for a small one.

However, GDP should not be confused with prosperity. It measures quantity, not quality and not distribution. A traffic accident makes GDP rise, because the repair shop and the hospital earn money from it. Unpaid work at home, on the other hand, does not show up at all, even though it is enormously valuable.

How the number comes about

In Germany, the Federal Statistical Office calculates GDP. To do so, it evaluates sales tax data, company surveys, foreign trade figures, and information on government spending. Because not all data is available immediately, a quick estimate is issued first. This is later revised upward or downward several times, which often causes confusion in the news.

There are several calculation methods that are supposed to yield the same result. The most illustrative is the expenditure approach: one adds up what private households buy, what the state spends, what companies invest, and what is sold abroad. Imports are then subtracted from the last item, since they were not produced domestically. As a check, what everyone involved earned in the process is also calculated.

A common misconception concerns prices. If everything becomes ten percent more expensive while the same amount is still produced, GDP rises purely arithmetically. This is why nominal GDP at current prices is distinguished from real GDP, from which price increases have been calculated out. In serious reports, it is almost always real GDP that is meant.

GDP in headlines and in the AI debate

Four times a year, authorities report new quarterly figures, and stock markets often react within minutes. Sentences like “The German economy shrank by 0.2 percent” always refer to GDP. When comparing countries, GDP per capita is used, meaning the figure divided by the population. Otherwise a populous country would automatically appear richer than a small one.

The indicator also plays a role in the debate about artificial intelligence. Consulting firms regularly estimate that AI could raise global GDP by several percent over the coming decades. Such forecasts are calculation models, not measurements, and should be read with corresponding caution.

There is an interesting contradiction that economists argue about. Although software and digital services have greatly changed everyday life, measured productivity has recently grown rather slowly. Some suspect that GDP poorly captures free digital offerings. Others simply consider the impact of new technology to be overestimated.