7th CPC DA Calculation : 
7TH CPC PAY SCALE CALCULATOR FROM 1.1.2016
What are the 7th CPC’s Recommendations Regarding Dearness Allowance?
Dearness Allowance is one of the important issues that the Pay Commission deals with.
The calculation method that was recommended by the 6th Pay Commission was radically different from the ones suggested by all the previous Pay Commissions.
Dearness Allowance, which was increasing by 1 or 2% until the 5th Pay Commission suddenly shot up to double-digit numbers. Until the 5th CPC, the All India Consumer Price Index Number for Industrial Workers 1982 = 100 was used for calculating dearness allowance. From the 6th Pay Commission onwards, CPI (IW) 2001 = 100 was used for calculating the DA.
There was another crucial change that the 6th CPC made. it recommended that the Reference Base Index be changed from 306.33. As a result, 115.76 became the new Reference Base Index from 01.01.2006 onwards.
The report says…
The Commission assuming that the rate of Dearness Allowance would be 125 percent at the time of implementation of the new pay.
The Dearness Allowance (DA) is paid to Central Government employees to adjust the cost of living and to protect their Basic Pay from erosion in the real value on account of inflation. Presently, DA is based on the All India Consumer Price Index (Industrial Workers).
The JCM-Staff Side has suggested that the existing formula for the calculation of DA may continue.
Analysis and Recommendations
The VI CPC had recommended that the National Statistical Commission may be asked to explore the possibility of a specific survey covering government employees exclusively, so as to construct a consumption basked representative of government employees and formulate a separate index. This has, however, not been done.
Keeping in mind that the present formulation of DA has worked well over the years, and there are no demands for its alteration, the Commission recommends continuance of the existing formula and methodology for calculating the Dearness Allowance.
The prices of all items have been sourced from Labor Bureau, Shimla. These prices are used in the calculation of the CPI (IW) and subsequently the calculation of Dearness Allowance. In the current exercise the prices of all items are for the period July 2014-June 2015 and have been used in the calculation of DA at 119 percent operative from 01.07.2015.
Click to view the 6th CPC DA Table from 2006 to 2015
According to DA is worked out as 10% of basic pay from July 2018 but the order says it is 9%. I am not quite convinced how reduction of 1% resulted?