STATUS UPDATE — 8 OCTOBER 2026
This comparison covers a retired model generation. GPT-5.6 Sol, Terra and Luna have been replaced by GPT-6.
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GPT-6 Sol — ChatGPT Plus, Pro, Business and Enterprise since 7 October 2026
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GPT-6 Luna — ChatGPT Free and Go since 8 October 2026. In the API at $0.10 / $0.50 per million tokens
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GPT-6.1 Sol — $2.00 / $10.00 per million tokens
The comparison below is kept for reference on how the 5.6 line behaved. For current pricing see
the October 2026 model pricing table.
QUICK VERDICT — JULY 25, 2026
● Better overall intelligence (AA Index): GPT-5.6 Sol — 58.9 (#2) vs Opus 5 not yet ranked
● Better ARC-AGI-3: Claude Opus 5 — 30.2% (3× next closest model)
● Better output price: Claude Opus 5 — $25/M vs Sol $30/M
● Better effort control: Claude Opus 5 — 5-level toggle vs Sol's Max Reasoning (binary)
● Better writing quality: Claude Opus 5 — Anthropic's consistent strength
● Better tool access in voice: Claude Opus 5 — Gmail/Slack/Canva mid-conversation
● US data residency: Both — Anthropic US, OpenAI US
| Feature | Claude Opus 5 | GPT-5.6 Sol |
|---|
| Input /1M | $5 | $5 |
| Output /1M | $25 | $30 |
| AA Intelligence Index | Not yet ranked | 58.9 (#2) |
| ARC-AGI-3 | 30.2% | Not published |
| Effort control | 5-level toggle | Max Reasoning (binary) |
| Voice tool access | Gmail, Slack, Canva | No tool access in voice |
| Hard refusals | Replaced by auto-fallback | Standard refusal policy |
Decision Framework
Claude Opus 5 for: Writing quality (Anthropic's consistent benchmark advantage), long-form content, analysis, agentic workflows needing fine-grained cost control (5-level effort toggle), voice with Gmail/Slack tool access, and production workloads that can't tolerate hard refusals (auto-fallback). 17% cheaper on output.
GPT-5.6 Sol for: Overall intelligence benchmark leadership (AA Index #2 at 58.9 — Opus 5 not yet ranked), web research (essentially level on research tasks per Anthropic's own disclosure), ChatGPT Work persistent sessions, and OpenAI ecosystem integrations (Canvas, Code Interpreter, Codex). Sol's full-duplex GPT-Live voice is also more natural conversationally than Opus 5's turn-based voice.
Last updated July 25, 2026. Related: Claude Opus 5 full review → · Claude Opus 5 vs Fable 5 → · Claude voice vs ChatGPT voice →