The magic of Inflation

Inflation rates of India (2009)

This post tracks inflation rates of India for the year 2009, like Inflation rates of India (2008) did for 2008. Before that, a few facts about inflation rate calculation in India.

- Inflation in India is based on Wholesale Price Index
- A set of 435 commodities are used for the WPI based inflation calculation
- The base year for WPI calculation is 1993-94
- WPI is available at the end of every week (generally Saturday), for a period of 1 year ended that day
- It has a time lag of 2 weeks (WPI for the year ended two weeks back will be available this week)

Latest Inflation Rate
- 2009 Apr 18 - 0.57% (via)
(for 12 months ended on the given date)

Previous Inflation Rates (for 12 months ended on given date)
- 2009 Apr 11 - 0.26% (via)
- 2009 Apr 04 - 0.18% (via)
- 2009 Mar 28 - 0.26% (via)
- 2009 Mar 21 - 0.31% (via)
- 2009 Mar 14 - 0.27% (via)
- 2009 Mar 07 - 0.44% (via)
- 2009 Feb 28 - 2.43% (via)
- 2009 Feb 21 - 3.03% (via)
- 2009 Feb 14 - 3.36% (via)
- 2009 Feb 7 - 3.92% (via)
- 2009 Jan 31 - 4.39% (via)
- 2009 Jan 24 - 5.07% (via)
- 2009 Jan 17 - 5.64% (via)
- 2009 Jan 10 - 5.60% (via)
- 2009 Jan 3 - 5.24% (via)
How is WPI inflation rate calculated in India?

With inflation rate surging to new heights, the term is more in the news than ever in India. While leaving aside the debate on whether India should adopt CPI (Consumer Price Index) based inflation calculation rather than the current WPI (Wholesale Price Index) based one, let’s find in detail how inflation rate is calculated in India; which is the WPI based inflation rate.

What is inflation?
Inflation rate of a country is the rate at which prices of goods and services increase in its economy. It is an indication of the rise in the general level of prices over time. Since it’s practically impossible to find out the average change in prices of all the goods and services traded in an economy (which would give comprehensive inflation rate) due to the sheer number of goods and services present, a sample set or a basket of goods and services is used to get an indicative figure of the change in prices, which we call the inflation rate.

Mathematically, inflation or inflation rate is calculated as the percentage rate of change of a certain price index. The price indices widely used for this are Consumer Price Index (adopted by countries such as USA, UK, Japan and China) and Wholesale Price Index (adopted by countries such as India). Thus inflation rate, generally, is derived from CPI or WPI. Both methods have advantages and disadvantages. Since India uses WPI method for inflation calculation, let’s go in to the details of WPI based inflation calculation.

How is WPI (Wholesale Price Index) calculated?
In this method, a set of 435 commodities and their price changes are used for the calculation. The selected commodities are supposed to represent various strata of the economy and are supposed to give a comprehensive WPI value for the economy.

WPI is calculated on a base year and WPI for the base year is assumed to be 100. To show the calculation, let’s assume the base year to be 1970. The data of wholesale prices of all the 435 commodities in the base year and the time for which WPI is to be calculated is gathered.

Let's calculate WPI for the year 1980 for a particular commodity, say wheat. Assume that the price of a kilogram of wheat in 1970 = Rs 5.75 and in 1980 = Rs 6.10

The WPI of wheat for the year 1980 is,
(Price of Wheat in 1980 – Price of Wheat in 1970)/ Price of Wheat in 1970 x 100

i.e. (6.10 – 5.75)/5.75 x 100 = 6.09

Since WPI for the base year is assumed as 100, WPI for 1980 will become 100 + 6.09 = 106.09.

In this way individual WPI values for the remaining 434 commodities are calculated and then the weighted average of individual WPI figures are found out to arrive at the overall Wholesale Price Index. Commodities are given weight-age depending upon its influence in the economy.

How is inflation rate calculated?
If we have the WPI values of two time zones, say, beginning and end of year, the inflation rate for the year will be,

(WPI of end of year – WPI of beginning of year)/WPI of beginning of year x 100

For example, WPI on Jan 1st 1980 is 106.09 and WPI of Jan 1st 1981 is 109.72 then inflation rate for the year 1981 is,

(109.72 – 106.09)/106.09 x 100 = 3.42% and we say the inflation rate for the year 1981 is 3.42%.

Since WPI figures are available every week, inflation for a particular week (which usually means inflation for a period of one year ended on the given week) is calculated based on the above method using WPI of the given week and WPI of the week one year before. This is how we get weekly inflation rates in India.

Characteristics of WPI
Following are the few characteristics of Wholesale Price Index

# WPI uses a sample set of 435 commodities for inflation calculation

# The price from wholesale market is taken for the calculation

# WPI is available for every week

# It has a time lag of two weeks, which means WPI of the week two weeks back will be available now


There are certain arguments in the open saying that the government shall adopt Consumer Price Index (CPI) method for inflation calculation, which gives a more correct picture. More of that in another post...
Commodities and their weightages in WPI calculation of India, Part I

As on today, India uses a basket of 435 commodities and a base year of 1993-94 for its Wholesale Price Index (WPI) based inflation rate calculation. The 435 commodities used for finding WPI range from food items like rice, wheat to petroleum products to medicines and are given weightages depending upon their importance and impact on the economy. Discussions are going on to revise the number of commodities to 980 and base year to 2004-05.

The 435 commodities are divided to various groups and subgroups. Individual commodities, and as a result, groups and subgroups have weightages. On a broader level, the 435 commodities are grouped into,

1. Primary Articles
2. Fuel, Power, Light & Lubricants
3. Manufactured Products

Primary Articles consist of food grains, fruits and vegetables, milk, eggs, meats and fishes, condiments and spices, fibers, oil seeds and minerals. Fuel, Power, Light & Lubricants consist of coal and petroleum related products, lubricants, electricity etc. Manufactured Products consist of dairy products, atta, biscuits, edible oils, liquors, cloth, toothpaste, batteries, automobiles etc. The group weightages are 22.02525%, 14.22624% and 63.74851% for Primary Articles, Fuel, Power, Light & Lubricants and Manufactured Products respectively. The total adds up to 100.

There are three more parts to this article. In the first part, we will cover Primary Articles, its sub classifications, individual commodities and their weightages. Second part is for Fuel, Power, Light & Lubricants, its sub classifications, individual commodities and their weightages and third part deals with Manufactured Products, its sub classifications, individual commodities and their weightages.
Base year and number of commodities used for inflation calculation in India

By this year end, the government will adopt a revised Wholesale Price Index (WPI), besides considering actual prices from next month.

Instead of the current 435 commodities, the revised WPI will have 980 commodities included in it, which will be rationalized by incorporating new items, removing unimportant items and amalgamating similar items.

The base year will also be revised to 2004-05 from the current base year of 1993-94. Thus the new WPI would give a more accurate figure for inflation. More news here.

So finally, the government is doing something on various debates happened over inflation calculation in India.The magic of Inflation

Business Standard reported, “Inflation based on the Wholesale Price Index (WPI) dropped to 3.79% for the week ended August 25 from 3.94% in the previous week. Inflation close to 7% few months back to 3.79% is more welcomed than ever. As one won’t be having any doubts regarding the importance of inflation to an economy and how it affects the economy, let’s see how it is calculated in India.

But before that, there are two methods to calculate inflation rate; Wholesale Price Index (WPI, introduced in 1902) and Consumer Price Index (CPI, introduced in the 1970s). In WPI, the calculation of inflation is done on the basis of the average rate of change in prices of a set of commodities in the wholesale market. Where as CPI is a statistical time-series value based on the weighted average of rate of change in prices of a set of goods and services purchased by consumers. Thus the CPI is much more comprehensive and it catches the inflation value from the end-consumer's side rather than from the wholesale seller's side. CPI is published on a monthly basis while WPI is available every week and has the shortest possible time lag of 2 weeks. India uses WPI while most of the developed countries use CPI to calculate the inflation rate.

The prices of a set of 435 commodities (such as onion, rice, dal etc.) are used for calculating WPI in India. Economists say that India should adopt CPI for inflation calculation as it is the one that shows price rise an end-consumer would experience. Finance Ministry counters it saying that in India there are 4 CPI indices (CPI Industrial Workers, CPI Urban Non-manual Employees, CPI Agricultural Labourers and CPI Rural Labour) in existence which makes switching over to CPI riskier and complex and also CPI has too much lag time in reporting. But then, the question remains how the United States, the United Kingdom, Japan, France, Canada, Singapore and China use CPI for inflation calculation?