https://rogerhub.com/gpa-calculator-uc/
Note that the second link shows three variants of UC recalculated HS GPA. The weighted-capped one is one usually used on UC web sites, unless otherwise stated.
CSU recalculates HS GPA the same way as UC weighted-capped, except that a semester college course counts as two courses and two grades at CSU instead of one course and one grade at UC.