OpenAI's GPT-6 Astra scored full marks on Korea's college entrance exam. It was the only model to reach 450 points in the 2026 CSAT evaluation. The test covered Korean, English, maths, history and four science and social electives. Models answered without internet access. GPT-5.6, GPT-5.4, Claude Fable 5.1 and Gemini 3.1 Pro followed in that order. Astra also used the fewest tokens of any publicly available model tested. Its design compresses and reuses earlier reasoning steps instead of rethinking each task. Hanyang University's Lee Seung-hyun said retaining and revising earlier reasoning is the key change. The exam questions were already public, so training-data exposure cannot be ruled out. Korean industry figures said open-ended workplace problems are the better test.

• 450/450 perfect score
• 357,000 tokens used
• GPT-5.6: 448.5, 429,000 tokens
• Claude Fable 5.1: 447.5