Salary at the time of retirement multiply years of service divided by33years is formula for pansion
formula of pension calculationn
Although the variables vary from nation to nation, the basic formula generally involves 2.26 of old basic pension. Then you include 50 percent of minimum basic plus grade pay of the latest pay band, matched to pay scale from which you retire. You can find more from this link http://www.oecd.org/document/12/0,3746,en_2649_37411_43024076_1_1_1_37411,00.html.