Which is generally harder to get into: UIUC or UC San Diego?

The biggest practical tradeoff is that UC San Diego is more selective across its undergraduate applicant pool overall, while UIUC has a much wider gap between its most selective programs and many of its other majors. UCSD draws an exceptionally large applicant pool and is typically viewed as the tougher university for admission in a broad, schoolwide comparison. UIUC is also highly selective, but its overall admissions profile is less uniformly competitive across programs.

Major matters especially at UIUC. Computer science, engineering, business-related options, and a few other high-demand programs can be extraordinarily difficult to enter, sometimes making UIUC as difficult as or more difficult than UCSD for an applicant to those specific programs. Applicants to less oversubscribed UIUC colleges may face a meaningfully different level of selectivity.

UCSD also has competitive and capacity-limited majors, particularly in STEM, but its overall selectivity remains the clearer headline. Residency can affect the comparison as well: UCSD evaluates California residents within the UC context, whereas UIUC’s applicant pool and availability can look different for Illinois residents, out-of-state applicants, and international applicants.