GPT-6.1 Sol vs Claude Opus 5.5

Quick Answer

This comparison is about value more than ranking. Claude Opus 5.5 is the higher-scoring model, by six points on Artificial Analysis’s independent Intelligence Index. GPT-6.1 Sol is dramatically cheaper to run: it lists at half Opus’s token price and, because it writes far fewer tokens, it finished the same benchmark at roughly an eighth of the cost per task.

For hard, high-stakes steps, Opus 5.5 may be worth it. For repeated, long-running, or high-volume work, GPT-6.1 Sol usually gives more accepted output per dollar.

At a Glance

What Each Model Is For

GPT-6.1 Sol is OpenAI’s model for repeated, long-running work. OpenAI says it approaches GPT-6 Astra on agentic coding, computer use, and professional work at about a fifth of Astra’s price; the independent index puts it one point below Astra. It runs in ChatGPT Work and Codex, not yet in the regular Chat tab. Third-party pricing guides report higher rates for very long prompts above about 272K tokens.

Claude Opus 5.5 is Anthropic’s model for long-running agentic coding and knowledge work, sitting below Fable 5.1. It runs Claude Code, Claude Duet, and Claude’s document and dashboard tools.

Quality per Completed Task

A higher benchmark score means fewer failures on hard problems, on average. A lower price means more attempts for the same budget. The question is which effect dominates for your work.

On Artificial Analysis’s run, Opus’s six-point lead came with roughly 4x the output tokens and 8x the cost per task. For a task where Sol succeeds most of the time, that is a poor trade for Opus. For a task where Sol fails often and each failure costs a developer’s time to fix, Opus’s higher success rate can easily be worth it. That is why cost per completed task, including retries and human fixes, is the measure that matters.

A practical approach: run 20 representative tasks through each, count accepted results, add up API spend and review time, and divide. Many teams end up using both, with Sol as the default and Opus as the escalation path.

Caching and Token Use

Both offer large discounts on repeated context, which matters for agents that resend the same files every turn. Sol’s cached input is $0.10 per million tokens. Anthropic’s cache reads are similarly heavily discounted (Artificial Analysis lists a 95% cache discount for Opus 5.5), and its batch API halves prices for non-urgent jobs. Opus’s verbosity is partly controllable with effort settings; Sol is already economical with tokens at maximum effort.

Speed

Artificial Analysis measured Opus 5.5 generating faster per second (about 96 versus 57 tokens), but Opus also generates many more tokens, so total time to finish a hard task is often longer. For interactive work, try lower effort settings on either model.

Application Ecosystem

The tools around each model matter as much as the model. If your team already uses Claude Code with Code Review, or Claude’s Docs and Dashboards, Opus fits in directly. If you use ChatGPT Work, Codex, or Dots, Sol is the natural default there. Switching ecosystems for a model alone rarely pays off.

Choose GPT-6.1 Sol If

You run many agent tasks or long jobs, cost per task drives your decision, you work in Codex or ChatGPT Work, or your evaluation shows Sol succeeding often enough on your tasks.

Choose Claude Opus 5.5 If

Mistakes are expensive, your tasks are the hard tail where the extra quality changes outcomes, you rely on Claude Code, or your evaluation shows meaningfully more accepted results.

When Neither Is Ideal

For most everyday work, cheaper models such as GPT-6 Luna, Claude Sonnet 5.5, or DeepSeek V4.1 Flash are enough. For the cheapest near-frontier option outside these two ecosystems, see GPT-6 Astra vs Gemini 4 Argon.

Final Recommendation

Use GPT-6.1 Sol as the value default and Claude Opus 5.5 where its higher quality is measurably worth eight times the per-task cost. Let your own evaluation, not the leaderboard gap, decide where that line sits. See model routing and How to Make Cheaper AI Models Work Smarter.

Related Comparisons

• Claude Opus 5.5 vs Gemini 4 Argon
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• GPT-6 Astra vs Gemini 4 Argon
• Muse Wonder vs Claude Opus 5.5
• Codex vs Claude Code