GPT-6.1 Sol makes capable AI work cheaper. Claude Opus 5.5 earns higher scores on several demanding tests. Which offers better value depends on the work you need it to finish.
Research checked October 1, 2026. Prices are in USD. This article compares published evaluations; we have not run our own head-to-head test.
What changed with these releases
OpenAI released GPT-6.1 Sol on September 29, 2026. The API model ID is gpt-6.1-sol. It is an upgrade to GPT-6 Sol, positioned to bring more capable coding and professional work at a lower cost than GPT-6 Astra. OpenAI API changelog
Anthropic released Claude Opus 5.5 on September 22, 2026. Its API model ID is claude-opus-5-5. Anthropic describes improvements in coding, long-running agents, and professional work, alongside lower token prices than Opus 5. Anthropic release announcement
These are two specific models. GPT-6 Astra results should not be relabeled as GPT-6.1 Sol results.
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