UC GPA is based on the grades you earn in 10-11th for the UC a-g course requirements. You get up to 8 semesters of honors points for UC approved Honors courses (CA resident’s only), AP, IB or DE courses taken during 10-11th grades. This is the capped weighted UC GPA. UCLA and UCB will also consider the uncapped weighted UC GPA which gives unlimited honors points for these courses taken 10-11th grades.
Freshman grades are reviewed to determine if you meet the UC a-g course requirements but not included in the GPA calculation so you still need to do well Freshman year along with Senior year where low grades could result in your admission being rescinded.
Here is some UC capped weighted admit data for all the UC’s.
Freshman admit rates for UC GPA of 3.40-3.79:
UCB: 1.8%
UCLA: 2.2%
UCSD: 7.2%
UCSB: 10.1%
UCI: 11.1%
UCD: 16.6%
UCSC: 43.8%
UCR: 63.3%
UCM: 88.7%
Freshman admit rates for UC GPA of 3.80-4.19:
UCB: 12.6%
UCLA: 11.7%
UCSD: 38.7%
UCSB: 53.6%
UCD: 56.5%
UCI: 52.1%
UCSC: 75.7%
UCR: 90.1%
UCM: 96.1%
Freshman admit rates for UC GPA of 4.20 or above:
UCB: 42.7%
UCLA: 47.2%
UCSD: 84.2%
UCSB: 82.0%
UCD: 90.3%
UCI: 94.1%
UCSC: 92.7%
UCR: 97.5
UCM: 98.1%
Also look at the Freshman profiles for each campus which will give more detail on the uW UC GPA vs weighted UC GPA.
http://www.admission.ucla.edu/Prospect/Adm_fr/Frosh_Prof16.htm
http://admissions.berkeley.edu/student-profile
Also the Freshman profiles on the UC website which lists the UC GPA capped weighted 25th-75th percentiles for 2017:
http://admission.universityofcalifornia.edu/freshman/profiles/index.html
Just remember the more competitive the major, a higher GPA will be needed…