Quick Answer: India measures inflation through three key indices. The CPI (base year 2012) is published monthly by the National Statistical Office and covers retail prices including services. The WPI (base year 2011-12) is published monthly by the Office of the Economic Adviser and covers wholesale goods only. The GDP deflator — nominal GDP ÷ real GDP × 100 — is the broadest measure, released with national accounts. The RBI targets CPI, not WPI, because CPI reflects what consumers actually pay.
- Quick Answer: CPI vs WPI vs GDP Deflator at a Glance
- What Is an Inflation Index and Why Exams Keep Asking About It
- CPI: How the Consumer Price Index Is Built
- CPI Base Year and Combined CPI Facts
- WPI: How the Wholesale Price Index Is Built
- WPI Base Year and Headline Facts
- GDP Deflator: How It Is Calculated
- Why CPI Drives RBI Monetary Policy
- Headline vs Core Inflation: Exam Distinctions
- Key Differences Table: CPI vs WPI vs GDP Deflator
- Memory Tricks and One-Liners for Revision
- Previous Year Question Patterns and Practice MCQs
- Frequently Asked Questions
- Q: What is the base year of CPI in India?
- Q: Which ministry publishes the WPI?
- Q: Why does the RBI target CPI inflation instead of WPI?
- Q: How is the GDP deflator calculated?
- Q: What is headline vs core inflation?
- Related reading
Quick Answer: CPI vs WPI vs GDP Deflator at a Glance
| Feature | CPI | WPI | GDP Deflator |
|---|---|---|---|
| Publisher | National Statistical Office (NSO), MoSPI | Office of the Economic Adviser (OEA), DPIIT, Ministry of Commerce & Industry | NSO / MoSPI (with national accounts) |
| Base Year | 2012 | 2011-12 | Implicit — no fixed base year in concept |
| Coverage | Retail goods and services consumed by households | Wholesale transactions of goods only — no services | All goods and services produced in the economy (GDP) |
| Frequency | Monthly | Monthly | Quarterly/annual (with GDP releases) |
| Policy Use | RBI’s inflation target (4% ± 2%) | Tracking producer/wholesale prices | Deflating nominal GDP; broadest inflation view |
What Is an Inflation Index and Why Exams Keep Asking About It
An inflation index is a number that tracks how the price of a defined basket of goods and services changes over time, relative to a reference period called the base year. If the index rises from 100 to 106 in a year, inflation is roughly 6%.
Questions on CPI, WPI and the GDP deflator appear repeatedly in UPSC Prelims, SSC CGL, Banking exams and RBI Grade B — typically testing who publishes each index, the base year, basket composition, and why the RBI anchors policy to CPI. Verify current figures at the MoSPI website and RBI website before your exam date, since base years are revised periodically.
CPI: How the Consumer Price Index Is Built
The Consumer Price Index measures the average change in retail prices paid by households for a fixed basket of goods and services. Basket weights come from the Consumer Expenditure Survey conducted by the NSO. The CPI is compiled by the National Statistical Office (NSO) under the Ministry of Statistics and Programme Implementation, and released monthly.
CPI is published in three variants — Rural, Urban and Combined — and is divided into four main groups:
- Food and beverages (largest weight, roughly 46% in CPI-Combined)
- Fuel and light
- Clothing and footwear
- Housing (urban CPI only)
- Plus a miscellaneous group covering education, health, transport, personal care and other services
The inclusion of services is the single biggest structural difference from the WPI — a favourite exam point.
CPI Base Year and Combined CPI Facts
- Current CPI base year: 2012 = 100.
- The CPI-Combined is the headline retail inflation number quoted in news and used by the RBI.
- Rural, Urban and Combined series are released simultaneously, on the 12th of each month (for the previous month), subject to data availability.
- A revision of the base year (to a more recent year such as 2024) has been under consideration — always check the latest NSO release.
WPI: How the Wholesale Price Index Is Built
The Wholesale Price Index tracks price movements in wholesale bulk transactions of goods at the producer/dealer level — before they reach retailers. It is compiled by the Office of the Economic Adviser (OEA), Department for Promotion of Industry and Internal Trade (DPIIT), Ministry of Commerce and Industry, and released monthly.
Key structural fact: WPI does not cover services at all. Its three major components are Primary Articles, Fuel & Power, and Manufactured Products.
WPI Base Year and Headline Facts
- Current WPI base year: 2011-12 = 100.
- Manufactured products carry the largest weight in WPI (about 64.2%), followed by primary articles (about 22.6%) and fuel & power (about 13.2%).
- WPI is released on the 14th of each month (for the previous month), subject to data availability.
- The base year is revised periodically to reflect changing consumption and production patterns; a revision has been under discussion.
GDP Deflator: How It Is Calculated
The GDP deflator is the ratio of nominal GDP to real GDP, multiplied by 100:
GDP Deflator = (Nominal GDP ÷ Real GDP) × 100
It is called a “deflator” because it strips out price effects from nominal GDP to arrive at real output. Key exam points:
- Broadest coverage — includes every good and service counted in GDP, including services and government output.
- Computed by MoSPI/NSO and released with quarterly and annual national accounts data — so it is available less frequently than CPI or WPI.
- Unlike CPI/WPI, its basket is not fixed — weights change every period with the composition of GDP, so there is no fixed base year in concept (chain-linked in practice).
Why CPI Drives RBI Monetary Policy
Under the Flexible Inflation Targeting framework, India’s statutory inflation target is 4% CPI inflation with a tolerance band of ±2% (i.e., 2%–6%). The Monetary Policy Committee (MPC), constituted in 2016, uses CPI-Combined as its target measure. Reasons CPI beats WPI for policy:
- CPI reflects retail prices consumers actually pay, so it measures the cost of living directly.
- CPI includes services; WPI excludes them entirely.
- WPI is heavily influenced by global commodity and fuel prices and does not capture household experience of inflation.
The framework is codified in the amended RBI Act and reviewed every five years. See rbi.org.in for the current target and MPC resolutions.
Headline vs Core Inflation: Exam Distinctions
- Headline inflation = the total CPI inflation number reported in the news.
- Core inflation = CPI excluding food and fuel — items with high volatility driven by supply shocks and weather.
- The RBI watches core closely because it reflects underlying demand-side inflation and is more responsive to monetary policy; food and fuel spikes are often supply-driven and transient.
Key Differences Table: CPI vs WPI vs GDP Deflator
| Dimension | CPI | WPI | GDP Deflator |
|---|---|---|---|
| What it measures | Retail prices paid by consumers | Wholesale prices of goods | Prices of all domestically produced final goods and services |
| Services included? | Yes | No | Yes |
| Publisher | NSO (MoSPI) | OEA, DPIIT, Ministry of Commerce & Industry | NSO (MoSPI) |
| Base year | 2012 | 2011-12 | Implicit; basket changes each period |
| Frequency | Monthly | Monthly | Quarterly/annual |
| Policy role | RBI MPC target (4% ± 2%) | Indicator of producer-side prices | Converting nominal GDP to real GDP |
| Imports in basket? | Partly (consumed imports) | Yes (priced at wholesale) | No — only domestic production |
Memory Tricks and One-Liners for Revision
- “RBI loves CPI” — the MPC target is CPI-Combined, 4% ± 2%, since 2016.
- “WPI = Wholesale, no services” — goods only, from the Commerce Ministry’s Economic Adviser.
- “Deflator covers everything” — every good and service in GDP, but no imports.
- “CPI 2012, WPI 2011-12” — CPI’s base is a single year; WPI’s is written as a financial year.
- “Core = CPI minus food and fuel.”
- “NSO for CPI, OEA for WPI, deflator from national accounts.”
Previous Year Question Patterns and Practice MCQs
UPSC and SSC typically test the publisher, base year, basket composition, and the RBI’s target index. Practise with this set:
Q1. The base year of India’s Consumer Price Index (Combined) is:
(a) 2004-05 (b) 2010 (c) 2012 (d) 2011-12
Answer: (c) 2012
Q2. The Wholesale Price Index in India is released by:
(a) NSO, MoSPI (b) Office of the Economic Adviser, DPIIT (c) RBI (d) NITI Aayog
Answer: (b) Office of the Economic Adviser, DPIIT, Ministry of Commerce & Industry.
Q3. Which of the following is NOT included in WPI?
(a) Manufactured products (b) Primary articles (c) Fuel and power (d) Services
Answer: (d) WPI covers goods only.
Q4. GDP Deflator is calculated as:
(a) Real GDP ÷ Nominal GDP × 100 (b) Nominal GDP ÷ Real GDP × 100 (c) CPI ÷ WPI × 100 (d) Nominal GDP − Real GDP
Answer: (b)
Q5. Under the Flexible Inflation Targeting framework, the RBI’s target is CPI inflation of:
(a) 2% ± 2% (b) 4% ± 2% (c) 6% ± 2% (d) 5% ± 1%
Answer: (b) 4% with a 2%–6% tolerance band.
Frequently Asked Questions
Q: What is the base year of CPI in India?
CPI (Combined) uses base year 2012 = 100 and is published monthly by the National Statistical Office (NSO) under MoSPI, in Rural, Urban and Combined variants.
Q: Which ministry publishes the WPI?
The WPI is published by the Office of the Economic Adviser, DPIIT, Ministry of Commerce and Industry, monthly, with base year 2011-12.
Q: Why does the RBI target CPI inflation instead of WPI?
CPI reflects retail prices actually paid by consumers, includes services, and is the statutory target — 4% ± 2% — under the Monetary Policy Committee framework operational since 2016.
Q: How is the GDP deflator calculated?
GDP Deflator = (Nominal GDP ÷ Real GDP) × 100. It covers all goods and services produced within the economy and is released with national accounts data by MoSPI.
Q: What is headline vs core inflation?
Headline inflation is the total CPI inflation rate. Core inflation is CPI excluding food and fuel, used to judge underlying demand-side price pressure that monetary policy can influence.
Cross-check base years and latest releases at mospi.gov.in, the Office of the Economic Adviser and rbi.org.in, as base years are revised from time to time.
Related reading
- Thursday Economy Sprint Quiz: 15 Budget and Banking Awareness MCQs Solved in 12 Minutes
- RBI Monetary Policy Committee Explained: Repo Rate, Repo Corridor and Inflation Targeting for Banking Exams
Quick revision
- Food and beverages: (largest weight, roughly 46% in CPI-Combined)
- Plus a miscellaneous group covering education, health, transport, personal care and other services
- Current CPI base year: 2012 = 100.
- The CPI-Combined is the headline retail inflation number quoted in news and used by the RBI.
- Rural, Urban and Combined series are released simultaneously, on the 12th of each month (for the previous month), subject to data availability.
- A revision of the base year (to a more recent year such as 2024) has been under consideration — always check the latest NSO release.
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