In many cases, why do we use real GDP instead of nominal GDP? Real GDP is calculated using the prices at a selected base year, and, therefore, it will only change when real production changes, and will not be affected by changes of prices across years. Real GDP is adjusted for inflation. Real GDP is only impacted by the change in quantity produced, while nominal GDP is impacted by two variables at the same time: production in real terms and prices, and it is not able to isolate these two variables. All of the above.