nominal versus real GDP

Suppose your country produced the exact same number of cars, haircuts and loaves of bread two years running, but every price went up 10 percent. If you simply added up the cash value of everything, GDP would look 10 percent bigger, even though nobody actually got more stuff. That illusion is the problem nominal and real GDP are designed to solve. Nominal GDP is measured at the prices of the year it happened; real GDP strips out price changes so you can see whether the country truly produced more.

Nominal GDP, also called GDP at current prices, multiplies this year's quantities by this year's prices. Real GDP, also called GDP at constant prices, multiplies each year's quantities by the prices of a single fixed base year, so only the change in quantities can move the number. Suppose in year one a country makes 100 widgets at 1 dollar each, so nominal GDP is 100. In year two it makes 110 widgets, but the price has risen to 1.20, so nominal GDP is 132. That looks like 32 percent growth. But valued at the year-one price of 1 dollar, real GDP is 110, which is real growth of only 10 percent. The extra 22 was just inflation dressed up as growth.

This distinction is one of the first things every economist learns, because almost every meaningful comparison over time must use real GDP. When people ask whether an economy is really growing, whether wages are rising faster than prices, or whether one decade beat another, the honest answer always uses real, inflation-adjusted figures. Comparing nominal GDP across years is a classic way to fool yourself, and sometimes a way politicians try to fool others.