What is GDP? Nominal GDP and real GDP
GDP (gross domestic product) is the total value of all final goods and services made inside a country in one year. Final means sold to the last user (a loaf of bread, not the flour used to bake it, so nothing is counted twice).
Nominal GDP uses the prices of that year. If prices rise, nominal GDP rises even when no extra goods are made.
Real GDP removes the effect of inflation (price rise). It measures the true quantity produced.
Real GDP = Nominal GDP ÷ price index × 100 (price index = 100 in the base year).
GDP per head (per capita)
GDP per head = real GDP ÷ population. It shows the average output, and roughly the average income, per person. It is better than total GDP for comparing living standards between countries of different sizes.
Economic growth and the growth rate
Economic growth is an increase in real GDP over time.
Growth rate (%) = (real GDP this year − real GDP last year) ÷ real GDP last year × 100.
Actual growth is what really happens to real GDP. Potential growth is how fast the economy could grow if all its workers and machines were fully used. Potential grows when the amount or quality of resources grows. On a production possibility curve, actual growth is moving towards the curve; potential growth is the curve moving outwards.
Small rates add up because growth compounds. The rule of 70: years to double ≈ 70 ÷ growth rate. At 2% a year GDP doubles in about 35 years; at 7% in about 10.
The economic cycle and output gaps
Real GDP does not rise smoothly. It moves in an economic cycle (business cycle) around its long-run trend:
- Boom: fast growth, many jobs, prices may rise quickly.
- Slowdown: growth gets slower.
- Recession: real GDP falls, often defined as two quarters (6 months) in a row of falling real GDP; unemployment rises.
- Recovery: growth returns.
An output gap is the difference between actual and potential GDP. A positive gap (actual above potential) happens in a boom and can push up inflation. A negative gap (actual below potential) happens in a recession and means idle workers and machines.
Causes, benefits and costs of growth
Causes (factors of growth)
- More resources: more workers, more land or natural resources.
- Better resources: education and training (human capital) make workers more productive.
- Investment in machines, roads, ports, power and internet (physical capital).
- New technology and ideas (research, innovation).
- Demand: more spending by households, firms, government and exports can raise actual growth in the short run.
- Good institutions: stable rules, low corruption, open trade.
Benefits
- Higher incomes and living standards, more jobs.
- More tax money for schools, hospitals and roads.
- Less poverty. Several East Asian economies (South Korea, Taiwan) grew fast after 1960, and rising education and incomes later went with moves towards democracy.
Costs
- Environment: more pollution, carbon emissions and use of non-renewable resources.
- Inequality: gains may go mostly to some groups or regions.
- Inflation if demand grows faster than potential output.
- Stress, congestion, loss of old ways of life.
This is why many countries now aim for sustainable growth that also protects nature and future generations. GDP does not measure happiness, health or unpaid work, so it is only one measure of development.
Key formulas and definitions
- GDP = value of all final goods and services made in a country in one year
- Real GDP = Nominal GDP ÷ price index × 100
- Growth rate (%) = (new real GDP − old real GDP) ÷ old real GDP × 100
- GDP per head = real GDP ÷ population
- Output gap = actual GDP − potential GDP
- Rule of 70: years to double ≈ 70 ÷ growth rate (%)
- Recession = real GDP falls for two quarters in a row (common definition)
Worked examples
1. Real GDP rises from 200 billion to 210 billion. Find the growth rate.
Change = 210 − 200 = 10. Growth rate = 10 ÷ 200 × 100 = 5%.
2. Nominal GDP is 550 and the price index is 110 (base year = 100). Find real GDP.
Real GDP = 550 ÷ 110 × 100 = 500. Prices are 10% higher, so the real amount made is 500.
3. Nominal GDP grew by 8% and prices rose by 5%. Roughly what was real growth?
Real growth ≈ nominal growth − inflation = 8% − 5% = 3%.
4. Country A: real GDP $1,000 billion, 50 million people. Country B: $3,000 billion, 300 million people. Who has higher GDP per head?
A: $1,000 billion ÷ 50 million = $20,000 per head. B: $3,000 billion ÷ 300 million = $10,000 per head. B has bigger total GDP, but A has double the GDP per head.
5. Real GDP grows 2% but population grows 3%. What happens to GDP per head?
GDP per head ≈ 2% − 3% = −1%. Each person on average gets about 1% less, even though GDP grew.
6. An economy grows at 7% a year. About how long to double? And at 3.5%?
Rule of 70: 70 ÷ 7 = 10 years. 70 ÷ 3.5 = 20 years. Halving the rate doubles the time.
Common mistakes
- Using nominal GDP to measure growth. A price rise is not growth; always use real GDP.
- Thinking a recession means GDP is small. It means real GDP is falling, from whatever level.
- Comparing living standards using total GDP. Use GDP per head, because population sizes differ.
- Saying growth is always good. Growth can bring pollution, inequality and inflation; it must be sustainable.