With CYA of 60, shock level of FC is 18. A an 18x33 that averages 5 feet deep is about 19,600 gallons. To raise FC from 4 to 18 in 19,600 gallons will take 4 1/2 gallons of 6% bleach. If your average depth is not 5 feet you will need to adjust that.
You can use my pool calculator, see the link in my signature, to figure out things like this.
Remember that shocking means testing the FC level, adding enough chlorine to bring FC up from there to shock level, waiting a while for the chlorine to work and then repeating the process frequently, up to once per hour, until FC holds steady overnight.