Claude Opus 4.6 vs o3

Overview — our 12-test suite: Claude Opus 4.6 wins 3 tests (creative_problem_solving, long_context, safety_calibration), o3 wins 2 (structured_output, constrained_rewriting), and 7 tests tie. Safety and long-context — Claude Opus 4.6: 5/5 safety_calibration (tied for 1st of 55 models) vs o3: 1/5 (rank 32 of 55). Opus’s 5/5 long_context (tied for 1st of 55) vs o3’s 4/5 (rank 38 of 55) means Opus is more reliable when working with 30K+ token retrievals and long documents. Creative problem solving — Opus 5/5 (tied for 1st) vs o3 4/5 (rank 9), so Opus produces more non-obvious feasible ideas in our tasks. Structured output and constrained rewriting — o3 scores 5/5 on structured_output (tied for 1st) vs Opus 4/5 (rank 26 of 54); o3 4/5 constrained_rewriting (rank 6 of 53) vs Opus 3/5 (rank 31). That translates to tighter JSON/schema compliance and better compression into strict character limits for o3. Third‑party benchmarks (Epoch AI): on SWE‑bench Verified, Claude Opus 4.6 scores 78.7% (rank 1 of 12) vs o3 62.3% (rank 9 of 12), favoring Opus for real GitHub issue resolution style coding tasks; on MATH Level 5, o3 scores 97.8% (rank 2 of 14) while Opus has no math_level_5 entry in the payload; on AIME 2025, Opus scores 94.4% (rank 4 of 23) vs o3 83.9% (rank 12 of 23). Ties: strategic_analysis, tool_calling, faithfulness, classification, persona_consistency, agentic_planning, and multilingual are tied — both models are equally solid there. Practical meaning: pick Opus for safer, long-context, agent-style workflows and some coding tasks (SWE‑bench leader); pick o3 for schema-accurate outputs, constrained rewriting, and peak performance on MATH Level 5.

Raw prices from the payload: Claude Opus 4.6 charges $5 input and $25 output per mTok; o3 charges $2 input and $8 output per mTok. If you assume equal input+output tokens, cost per million tokens (1 mTok input + 1 mTok output) is $30 for Opus vs $10 for o3. At 10M tokens/month that becomes $300 vs $100; at 100M tokens/month it's $3,000 vs $1,000. Who should care: startups and high-volume apps generating many tokens (billing scale >10M tokens/month) will see meaningful savings with o3; teams that need Opus’s 5/5 safety and 5/5 long-context may justify the premium despite the $20/mTok output gap.

Choose Claude Opus 4.6 if you need: long-context accuracy (5/5), strong safety calibration (5/5), agentic planning across workflows, or top SWE‑bench Verified coding performance (78.7% on SWE‑bench, rank 1). Choose o3 if you need: strict JSON/schema compliance and reliable structured outputs (5/5), better constrained rewriting (4/5), or top math competition performance (97.8% on MATH Level 5) while keeping costs low ($10 per combined mTok vs $30 for Opus). If budget is tight at scale (≥10M tokens/month), favor o3; if safety and multi-hour workflows are critical, budget for Opus.