Acceptance

i have a 3.0 gpa and im a out of state admission what are my chance on getting into a cal state

What is your SAT or ACT score? Intended major? Can you afford around $36-40K/ year to attend? Specific campuses you are interested in attending? CSU’s admit by eligibility index and major so you need to calculate your CSU GPA 10-11th grades only for the a-g course requirements and a cap on 8 semesters of AP/IB courses taken 10-11th for the extra honors points.
https://www2.calstate.edu/apply/eligibility-index

Minimum EI to apply is 2950 SAT for in-state and 3502 OOS. Some campuses have higher EI thresholds than the minimums. The non-impacted campuses such as San Francisco, Bakersfield, Channel Islands, Stanislaus, Dominguez Hills will accept applicants at the minimum EI threshold as long as they meet the a-g course requirements.
https://www2.calstate.edu/apply/freshman/getting_into_the_csu

Bottom line, yes you can get into a Cal state if you meet all the requirements and can afford to pay full fees. No financial aid for OOS students.
Depending upon your test scores, the Top CSU’s are not possible but that leaves many more campuses that are very possible.

act 25 for the first try

You’d probably get into the less competitive campuses but, don you really want to go to one of them, let alone pay for them?
If so, be sure you complete the a-g course list. lots of OOS kids don’t have the same requirements locally and miss out on something like the semester of Art, which will get you immediately disqualified.

An ACT of 25 is approximately a 1210 SAT. If your CSU GPA is 3.0, then your eligibility index is 3610. Minimum EI for OOS applicants is 3502.

The majority of CSU’s would probably accept you depending upon major and with these exceptions: Cal Poly San Luis Obispo, Cal Poly Pomona, San Diego State, Cal State Long Beach, Cal State Fullerton, Fresno State, San Jose State (some majors), Chico State.

Also applying for an impacted major can raise the bar on the EI thresholds so your chances will be major dependent.

So what is your intended major and are you willing to attend the less popular campuses?

computer science is my intended major

San Francisco state would be a great option since their CS program is not impacted.

Other CSU’s to consider for CS which are not impacted would be Bakersfield, Channel Islands, Dominguez Hills, Humboldt, East Bay, Sacramento, San Bernardino, Sonoma and Stanislaus.

It really depends upon which location(s) you prefer and if they are affordable with no financial aid other than Federal aid if you are eligible.