Here is the UC GPA calculator: http://rogerhub.com/gpa-calculator-uc/
As stated above, only 10-11th grades for the a-g courses are included in the GPA calculation. Senior grades are not considered for admissions, but are required to keep your provisional admission at the UC’s.
The average UC GPA for all the UC’s except UCR/UCM/UCSC is 4.0+. If your UC GPA is below this threshold, then having a high SAT/ACT will help but there are not guarantees. EC’s and essays are an important part of your application and can also help your chances, but depending upon your GPA, it will not overcome a lower than average GPA. The 3 things that are considered the most important in your UC application are GPA, Course Rigor and Test scores.
There are some outstanding Cal States (if in-state) and private schools that may be options, so do not use focus on the UC’s. Also UCR/UCM and UCSC are very good schools so do not dismiss them. All you can do is study hard for the SAT, continue to do well in school, apply in the Fall and hope for the best.