The growth rate of per capita income at current prices is higher than that of per capita income at constant prices, because the latter takes into account the rate of

1. National Income Aggregates: GDP and NNP (basic)

Hello! To understand how an economy grows, we first need to master the basic building blocks of national accounting. Think of these aggregates as different ways to measure the "pulse" of an economy. The most common starting point is Gross Domestic Product (GDP), which measures the total market value of all final goods and services produced within a country's geographic borders over a specific period. It is purely territorial—it doesn't matter if the producer is a citizen or a foreigner, as long as the production happens inside the country.

However, we often want to know the income belonging specifically to our citizens, even those working abroad. This is where Gross National Product (GNP) comes in. We calculate GNP by taking the GDP and adding Net Factor Income from Abroad (NFIA), which is the difference between what our residents earn abroad and what foreigners earn within our borders Macroeconomics (NCERT class XII 2025 ed.), Chapter 2: National Income Accounting, p.25. Essentially, GNP shifts the focus from where the production happens to who owns the means of production.

Finally, we must account for the fact that machines, tools, and buildings wear out over time; this is called Depreciation or capital consumption. To get the "true" or "Net" value of what we've produced, we subtract this wear and tear from our Gross figures. Thus, Net National Product (NNP) is simply GNP minus Depreciation Indian Economy, Nitin Singhania (2nd ed. 2021-22), Chapter 1: National Income, p.9. NNP is considered one of the cleanest measures of a nation's wealth because it accounts for both the global earnings of citizens and the cost of maintaining the country's capital stock.

Concept	Focus Area	Key Formula
GDP	Geography (Within borders)	Total Value of Output
GNP	Citizenship (Domestic + Overseas)	GDP + NFIA
NNP	True Income (Adjusted for wear/tear)	GNP – Depreciation

Sources: Macroeconomics (NCERT class XII 2025 ed.), Chapter 2: National Income Accounting, p.25; Indian Economy, Nitin Singhania (2nd ed. 2021-22), Chapter 1: National Income, p.9; Indian Economy, Vivek Singh (7th ed. 2023-24), Fundamentals of Macro Economy, p.17

2. Per Capita Income: Definition and Logic (basic)

When we look at a nation's economy, the Total Income (or Gross Domestic Product) tells us the size of the overall economic pie. However, this figure can be misleading if we want to understand the well-being of the actual people living there. For example, a country with a massive population might have a huge total income, yet its citizens could be living in poverty. To solve this, we use Per Capita Income (PCI), which is the average income earned per person in a given area in a specified year Understanding Economic Development. Class X . NCERT(Revised ed 2025), DEVELOPMENT, p.7.

The logic behind Per Capita Income is simple division: you take the Total National Income and divide it by the Total Population. This metric allows us to compare countries or states of different sizes on a level playing field. For instance, while India has a much larger total economy than many European nations, those nations often have a higher PCI because their total income is distributed among fewer people. In India, comparing states like Haryana and Bihar using PCI shows us that an average person in Haryana earns significantly more than one in Bihar, making it a better measure of relative development than looking at state-wide totals alone Understanding Economic Development. Class X . NCERT(Revised ed 2025), DEVELOPMENT, p.9.

To truly understand how prosperity changes, we must look at the growth rates of both income and population. If a country's GDP grows by 8% but its population also grows by 8%, the average person isn't actually any better off—the per capita income remains the same. Mathematically, if population grows at 1% and GDP grows at 8%, the Per Capita GDP will grow by approximately 6.9% Indian Economy, Vivek Singh (7th ed. 2023-24), Fundamentals of Macro Economy, p.17. Furthermore, we distinguish between Nominal PCI (calculated at current market prices) and Real PCI (calculated at fixed base-year prices). Real PCI is the gold standard for measuring progress because it ignores the "illusion" of rising prices (inflation) and focuses only on whether the actual volume of goods and services available to each person has increased.

Sources: Understanding Economic Development. Class X . NCERT(Revised ed 2025), DEVELOPMENT, p.7, 9; Indian Economy, Vivek Singh (7th ed. 2023-24), Fundamentals of Macro Economy, p.17

3. Inflation and Price Indices (intermediate)

To understand the difference between nominal and real values, we must first understand how we track the 'price level' itself. In economics, we use Price Indices to measure inflation. When we calculate Per Capita Income at current prices, we are looking at the nominal value—it reflects both the actual increase in goods/services produced and the increase in their prices. However, to find the Per Capita Income at constant prices, we value those goods at a fixed base-year price. This 'deflates' the value, removing the effects of inflation so we can see the true volume of growth Indian Economy, Nitin Singhania, Chapter 1, p.7.

In India, we primarily use two indices to track these price movements: the Wholesale Price Index (WPI) and the Consumer Price Index (CPI). The WPI tracks prices at the factory gate or wholesale level and excludes services entirely. In contrast, the CPI tracks the prices paid by the final consumer and includes both goods and services. Because the CPI reflects the actual cost of living for a household, the Reserve Bank of India (RBI) uses it as the key measure for deciding monetary policy rates Indian Economy, Nitin Singhania, Chapter 4, p.68.

A critical distinction between these two lies in their composition. Food items carry a much higher weight in the CPI (approx. 46%) compared to the WPI (approx. 22%), making the CPI highly sensitive to fluctuations in crop prices. Furthermore, economists often look at Core Inflation, which is calculated by taking the CPI and excluding volatile categories like food and fuel. This helps policy makers see the underlying long-term inflation trend without the 'noise' of temporary price shocks Indian Economy, Nitin Singhania, Chapter 4, p.69.

Feature	Wholesale Price Index (WPI)	Consumer Price Index (CPI)
Primary Level	Wholesale/Producer level	Retail/Consumer level
Scope	Only Goods	Goods and Services
Food Weight	Lower (~22%)	Higher (~46%)
Base Year	2011-12	2012

Sources: Indian Economy, Nitin Singhania, Chapter 1: National Income, p.7; Indian Economy, Nitin Singhania, Chapter 4: Inflation, p.68-69

4. The Concept of Base Year (intermediate)

In our journey to understand economic growth, we often encounter two sets of numbers: one that looks very high (Nominal) and one that looks more modest (Real). The bridge between these two is the Base Year. Think of the base year as a standard yardstick or a fixed point in time used for comparison. By valuing today's production at the prices that existed in a specific past year, we can strip away the "noise" of inflation and see the actual physical growth of the economy Indian Economy, Nitin Singhania, National Income, p.8.

Choosing a base year is a clinical process. It cannot be just any year; it must be a "normal year"—meaning a period free from extreme price fluctuations, severe natural disasters, or massive economic shocks that could distort the data Indian Economy, Nitin Singhania, National Income, p.8. When we use these fixed prices to calculate value, we refer to the result as being at Constant Prices. In contrast, using today's market prices gives us values at Current Prices.

In India, the current base year utilized by the National Statistical Office (NSO) is 2011-12. However, economies are dynamic; new industries emerge (like digital payments) and old ones fade. Therefore, the government periodically revises the base year to ensure the "basket of goods" being measured reflects modern consumption patterns. This revision is crucial for calculating the GDP Deflator, a tool used to determine how much the overall price level has risen between the base year and the current year Macroeconomics (NCERT class XII 2025 ed.), National Income Accounting, p.34.

Term	Price Level Used	Economic Meaning
Constant Prices	Base Year Prices	Reflects Real volume/output growth.
Current Prices	Today's Market Prices	Reflects Nominal growth (Output + Inflation).

Sources: Indian Economy, Nitin Singhania, National Income, p.8; Macroeconomics (NCERT class XII 2025 ed.), National Income Accounting, p.34

5. International Comparison: GDP at PPP (intermediate)

When we compare the economies of different countries, using the market exchange rate (Nominal rate) can be quite misleading. For instance, if you convert ₹8,000 into dollars at a market rate of $1 = ₹80, you get $100. However, those ₹8,000 might buy you a week's worth of groceries in India, while $100 might only last two days in New York. This discrepancy exists because the prices of non-traded goods (like haircuts or domestic help) are much cheaper in developing nations. To fix this distortion and make a "real" international comparison, economists use Purchasing Power Parity (PPP).

According to the International Monetary Fund (IMF), the PPP exchange rate is the rate at which one currency is converted into another to ensure that a given amount of the first currency will purchase the same volume of goods and services in the second country as it does in the first Vivek Singh, Fundamentals of Macro Economy, p.25. Essentially, it equalizes the purchasing power of different currencies. A standard way to derive this is by calculating the ratio of Abroad Price to Domestic Price for a representative basket of goods Vivek Singh, Fundamentals of Macro Economy, p.24. For example, if a specific basket costs $1 in the US and ₹35 in India, the PPP exchange rate is $1 = ₹35, regardless of what the bank's market rate says.

It is important to understand that PPP is not static. If inflation is higher in one country than another, the PPP exchange rate will change over time to reflect the loss of purchasing power in the high-inflation country NCERT Class XII, Open Economy Macroeconomics, p.96. However, if both countries have identical inflation rates, the PPP exchange rate remains constant Vivek Singh, Fundamentals of Macro Economy, p.25. This metric is vital for organizations like the World Bank and IMF when assessing the true standard of living and poverty levels across the globe Vivek Singh, International Organizations, p.396.

Feature	Nominal Exchange Rate	PPP Exchange Rate
Basis	Market demand and supply of currency.	Relative cost of a basket of goods.
Utility	Used for international trade and finance.	Used for comparing living standards (Real GDP).
Stability	Highly volatile (changes daily).	More stable (changes with inflation).

Sources: Indian Economy, Vivek Singh (7th ed. 2023-24), Fundamentals of Macro Economy, p.24-25; Macroeconomics (NCERT class XII 2025 ed.), Open Economy Macroeconomics, p.96; Indian Economy, Vivek Singh (7th ed. 2023-24), International Organizations, p.396

6. Real vs. Nominal Values (Current vs. Constant Prices) (intermediate)

When we talk about national income or per capita income, we often hear two different figures: one at current prices and another at constant prices. To understand the health of an economy, we must distinguish between the two. Nominal values (at current prices) are calculated using the prevailing market prices of the same year the goods were produced. This means if you are looking at the income for 2023, you multiply the quantities produced by 2023 prices. However, this figure can be deceptive because it reflects changes in both the actual volume of production and the price level (inflation). Macroeconomics NCERT Class XII, Chapter 2, p.29

To see the "real" picture, we use Real values (at constant prices). This method keeps prices fixed at a specific Base Year (currently 2011-12 in India) so that any increase in value strictly represents an increase in the quantity of goods and services produced. For instance, if a country produces 100 units of grain in two consecutive years, but the price doubles, the Nominal GDP will double even though the citizens have no more food than before. Real GDP, by using base-year prices, would show 0% growth, accurately reflecting the stagnant production. Nitin Singhania, National Income, p.8

The relationship between these two is captured by the GDP Deflator, which is the ratio of Nominal GDP to Real GDP. It acts as a comprehensive measure of inflation across the entire economy. Vivek Singh, Fundamentals of Macro Economy, p.33 Because prices generally rise over time, growth at current prices will almost always be higher than growth at constant prices. The difference between these two growth rates tells us how much of our "progress" is just rising prices rather than actual economic expansion. Vivek Singh, Fundamentals of Macro Economy, p.18

Feature	Current Prices (Nominal)	Constant Prices (Real)
Prices Used	Prevailing market prices of the current year.	Fixed prices of a chosen Base Year.
Impact of Inflation	Includes the effect of inflation.	Eliminates (adjusts for) inflation.
Utility	Useful for understanding current market value.	Better indicator of actual economic growth.

Sources: Macroeconomics NCERT Class XII, Chapter 2: National Income Accounting, p.29; Indian Economy, Nitin Singhania, Chapter 1: National Income, p.8; Indian Economy, Vivek Singh, Fundamentals of Macro Economy, p.18, 33

7. The GDP Deflator: Linking Nominal and Real (exam-level)

Hello! Now that we understand the difference between current and constant prices, let’s look at the bridge that connects them: the GDP Deflator. While terms like CPI (Consumer Price Index) are household names, the GDP Deflator is the economist's preferred lens for a truly comprehensive view of inflation. It is essentially the ratio of Nominal GDP (at current prices) to Real GDP (at constant prices). Since Nominal GDP captures both price and volume changes, and Real GDP captures only volume, dividing the two "deflates" the price effect, leaving us with a pure measure of how much prices have risen across the entire economy Indian Economy, Nitin Singhania, National Income, p.7.

The formula is straightforward: GDP Deflator = (Nominal GDP / Real GDP) × 100. If the result is 100 (or 1 in ratio form), it means prices haven't changed since the base year. If it is 120, it suggests a 20% increase in the general price level Indian Economy, Nitin Singhania, Inflation, p.68. What makes the Deflator special is its comprehensiveness. Unlike the CPI or WPI, which only track a specific "basket" of goods, the GDP Deflator accounts for every good and service produced within the country’s borders, including capital goods and services sold to the government Macroeconomics (NCERT class XII 2025 ed.), National Income Accounting, p.30.

However, there are crucial differences you must remember for the exam when comparing the Deflator to other indices:

Feature	GDP Deflator	CPI / WPI
Scope	All goods/services produced domestically.	Limited "basket" of representative goods.
Imports	Excludes prices of imported goods.	Includes prices of imported goods.
Weights	Weights change based on actual production.	Weights are fixed (until base year revision).

As noted by experts, while the GDP Deflator is the "best" indicator of overall inflation, it isn't used for monthly policy-making (like the RBI's inflation targeting) because GDP data is usually released only on a quarterly basis, whereas CPI data comes out every month Indian Economy, Nitin Singhania, Inflation, p.68.

Sources: Indian Economy, Nitin Singhania, National Income, p.7; Indian Economy, Nitin Singhania, Inflation, p.68; Macroeconomics (NCERT class XII 2025 ed.), National Income Accounting, p.30; Indian Economy, Vivek Singh, Fundamentals of Macro Economy, p.33

8. Solving the Original PYQ (exam-level)

You have just mastered the fundamental distinction between Nominal and Real economic variables. This question is a classic application of that logic: Per Capita Income at current prices (Nominal) captures the face value of income including inflation, while Per Capita Income at constant prices (Real) reflects the actual purchasing power by using a fixed base-year price. As you learned in Macroeconomics (NCERT class XII), the transition from current to constant prices is designed specifically to neutralize the impact of inflation so that we can see if the actual volume of goods and services has increased.

To arrive at the correct answer, ask yourself: What is the "filler" that makes nominal growth look higher than real growth? If the growth rate at current prices is higher, it means the total value rose not just because people earned more "stuff," but because the price of that stuff went up. Therefore, the constant price calculation is lower because it deliberately subtracts the (B) increase in price level. This ensures that the "Real" growth reflects only the quantum of output and not just a change in the currency's value, a concept echoed in Indian Economy by Nitin Singhania.

UPSC often includes growth of population (Option A) as a distractor; however, because the term is "Per Capita" (income divided by population), the population factor has already been mathematically addressed in both figures. Similarly, while money supply and wage rates (Options C and D) can influence the economy, they are not the specific accounting variables used to adjust nominal figures into constant ones. Always remember: the bridge between "Current" and "Constant" is always the price level.