What is the standard deduction for 2018 full time dependent student

It depends on your filing status.  Please see the information below.  If you are asking for him filing his own return, his standard deduction will be $12,000 by filing Single. 

https://ttlc.intuit.com/replies/4208574

Being a student doesn't matter.  If he is a dependent on someone else's return,
The Standard Deduction for an individual for whom an exemption can be claimed on another person's tax return is limited to the greater of:
…..$1,050 or
…..Your earned income for the year + $350

So you would get a minimum of $1,050 up to the max of 12,000.

Being a student is irrelevant. Being a dependent is relevant. A dependent’s standard deduction is $1050 or his earned income** plus $350, whichever is more; but not more than $12,000.

**For purposes of calculating the standard deduction, taxable scholarships are considered income, but not for IRA contributions or the Earned Income credit