Inflation measurement in India primarily revolves around two indices: the Consumer Price Index (CPI) and the Wholesale Price Index (WPI). While both track price movements, they differ in their scope, commodity baskets, and the economic agents they represent. Since the adoption of the “Flexible Inflation Targeting” (FIT) framework in 2016, the CPI has become the primary anchor for India’s monetary policy.
Consumer Price Index (CPI)
CPI measures the change over time in the general level of prices of goods and services that a reference population acquires, uses, or pays for consumption. It reflects the “cost of living” for households.
Key Variants of CPI
- CPI (Rural/Urban/Combined): Compiled by the National Statistical Office (NSO), Ministry of Statistics and Programme Implementation (MoSPI). The “Combined” index is the headline inflation measure for India.
- CPI for Industrial Workers (CPI-IW): Compiled by the Labour Bureau (Ministry of Labour and Employment). It is used to calculate Dearness Allowance (DA) for government employees and wages in industrial sectors.
- CPI for Agricultural Labourers (CPI-AL) and Rural Labourers (CPI-RL): Compiled by the Labour Bureau to monitor the cost of living in the unorganized rural sector and for revising minimum wages.
Composition and Weightage in CPI (Combined)
The CPI basket is divided into six main groups. Food and beverages carry the highest weight, making the index sensitive to agricultural supply shocks.
- Food and Beverages: ~45.86%
- Miscellaneous (Services like Health, Education, etc.): ~28.32%
- Housing: ~10.07% (Note: Housing is not included in CPI-Rural)
- Fuel and Light: ~6.84%
- Clothing and Footwear: ~6.53%
- Pan, Tobacco, and Intoxicants: ~2.38%
Wholesale Price Index (WPI)
WPI tracks the changes in the price of goods sold and traded in bulk by wholesale entities to other businesses. It captures “producer-level” inflation and does not include the price of services.
Components and Weightage of WPI
The current WPI series (Base Year 2011-12) tracks 697 commodities divided into three major groups:
- Manufactured Products: ~64.23% (Includes chemicals, basic metals, textiles, etc.)
- Primary Articles: ~22.62% (Includes food articles, non-food articles, and minerals)
- Fuel and Power: ~13.15% (Includes petrol, diesel, and electricity)
Comparative Analysis: CPI vs. WPI
The divergence between CPI and WPI often occurs due to differences in weightage, particularly regarding food and manufactured goods.
| Feature | Consumer Price Index (CPI) | Wholesale Price Index (WPI) |
| Primary Focus | Retail prices paid by consumers. | Prices at the first point of bulk sale. |
| Commodities Covered | Both Goods and Services. | Only Goods. |
| Compiling Agency | NSO (MoSPI). | Office of Economic Adviser (DPIIT), Ministry of Commerce. |
| Base Year | 2012 (Combined). | 2011-12. |
| Food Weightage | Significant (approx. 46%). | Relatively lower (approx. 24%). |
| Policy Application | Anchors RBI’s Monetary Policy. | Used for GDP deflator and industrial tracking. |
| Tax Inclusion | Includes Indirect Taxes (Final retail price). | Excludes Indirect Taxes (Factory gate price). |
Critical Differences in Measurement Logic
- Service Sector: WPI completely ignores the service sector (Banking, IT, Transport, etc.), whereas CPI allocates nearly 30% weight to services.
- Point of Sale: CPI is measured at the final stage of the supply chain; WPI is measured at the factory or mandi gate.
- Price Collection: CPI prices are collected from representative retail outlets across India, while WPI data is collected from institutional sources and major business hubs.
Important Indices and Terminologies
- Consumer Food Price Index (CFPI): A sub-component of CPI that exclusively tracks price changes in food items consumed by the population.
- Core Inflation: Calculated by stripping away the volatile components—Food and Fuel—from the Headline Inflation. It represents the underlying long-term inflation trend.
- Headline Inflation: The total inflation figure released by the government, including all components of the basket (inclusive of volatile food and fuel).
- Base Effect: The impact of the price levels of the previous year on the current inflation calculation. A very low price index in the previous year can artificially inflate the current year’s inflation percentage.
The GDP Deflator: The Comprehensive Alternative
While CPI and WPI are based on a fixed “basket” of goods, the GDP Deflator is a measure of the level of prices of all new, domestically produced, final goods and services in an economy.
- Formula: GDP Deflator = (Nominal GDP / Real GDP) × 100.
- Significance: It is more comprehensive as it covers the entire economy, including capital goods and government services. However, it is published only on a quarterly/annual basis, unlike the monthly CPI/WPI updates.
UPSC Prelims Facts and Trivia
- Urjit Patel Committee: This committee recommended that the RBI should transition from WPI to CPI (Combined) as the primary measure of inflation for monetary policy.
- Flexible Inflation Targeting (FIT): Under the RBI Act, 1934, the government (in consultation with RBI) sets the inflation target. The current target is 4% with a tolerance band of +/- 2% (i.e., 2% to 6%).
- Producer Price Index (PPI): Several government committees have recommended replacing WPI with PPI. PPI would measure price changes from the perspective of the producer, excluding trade and transport margins and indirect taxes.
- Substitution Bias: CPI often suffers from substitution bias because its fixed basket does not account for consumers switching to cheaper alternatives when a specific item’s price rises.