# Claude Opus 5.5 vs GPT-6.1 Sol

Claude Opus 5.5 (Anthropic) and GPT-6.1 Sol (OpenAI) compared on the facts each vendor publishes. On cost, pick GPT-6.1 Sol: it lists $2 in and $10 out per 1M tokens, against $4 and $20 for Claude Opus 5.5. For very long inputs, GPT-6.1 Sol lists the larger context window: 1.05M tokens against 1M. We have not run either model: every value below is Reported, with a link to its source.

Updated: 2026-10-29 · Canonical: https://theagenticweekly.com/compare/claude-opus-5-5-vs-gpt-6-1-sol · Evidence: Reported (not run by us)

## Specs

| | [Claude Opus 5.5](https://theagenticweekly.com/models/claude-opus-5-5) | [GPT-6.1 Sol](https://theagenticweekly.com/models/gpt-6-1-sol) |
|---|---|---|
| Price (as listed) | $4 in / $20 out per 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | $2 in / $10 out per 1M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) |
| Context window | 1,000,000 tokens (1M) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | 1,050,000 tokens (1.05M) ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) |
| Max output | 128,000 tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | 128,000 tokens ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) |
| Input | text, image ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | text, image ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) |
| Output | text ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | text ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) |
| Licence | Proprietary (API) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) |
| Released | Sep 22, 2026 ([source](https://www.anthropic.com/news)) | Sep 29, 2026 ([source](https://developers.openai.com/api/docs/changelog)) |
| Status | generally available | generally available |
| API id | claude-opus-5-5 ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | gpt-6.1-sol ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) |

## How to choose

- On cost, pick GPT-6.1 Sol: it lists $2 in and $10 out per 1M tokens, against $4 and $20 for Claude Opus 5.5.
- For very long inputs, GPT-6.1 Sol lists the larger context window: 1.05M tokens against 1M.
- GPT-6.1 Sol is newer, by 7 days.

## Benchmark snapshots (not our tests)

- LMArena WebDev leaderboard (Elo-style score) (independent, 2026-10-22, [source](https://arena.ai/leaderboard/webdev)): Claude Opus 5.5 (Max) 1807; GPT-6.1 Sol (Max) 1749
- Terminal-Bench 4.0 official leaderboard (independent, 2026-10-26, [source](https://www.tbench.ai/leaderboard/terminal-bench/4.0)): Claude Opus 5.5 (Claude Code, max) 64.8%; GPT-6.1 Sol (Codex, max) 58.2%
- SWE-bench Pro (Public), as reported by the vendors (vendor-reported, 2026-10-26, [source](https://benchmarkregistry.org/benchmarks/swe-bench-pro/public)): Claude Opus 5.5 (max) 89.9%
- Moonshot AI: Kimi K3.1 Pro launch post (Terminal-Bench 4.0) (vendor-reported, 2026-10-23, [source](https://www.kimi.ai/blog/kimi-k3-1-pro)): Claude Opus 5.5 66.4%

## FAQ

**Which is cheaper, Claude Opus 5.5 or GPT-6.1 Sol?** Claude Opus 5.5: $4 in / $20 out per 1M tokens. GPT-6.1 Sol: $2 in / $10 out per 1M tokens. Both prices are the vendors' own listed prices on the date each model was last verified.

**Which has the bigger context window?** GPT-6.1 Sol, with 1,050,000 tokens against 1,000,000.

**Which is better for coding?** We have not tested either. Sourced snapshots: LMArena WebDev leaderboard (Elo-style score) (independent, Oct 22, 2026): Claude Opus 5.5 (Max) 1807, GPT-6.1 Sol (Max) 1749; Terminal-Bench 4.0 official leaderboard (independent, Oct 26, 2026): Claude Opus 5.5 (Claude Code, max) 64.8%, GPT-6.1 Sol (Codex, max) 58.2%; SWE-bench Pro (Public), as reported by the vendors (vendor-reported, Oct 26, 2026): Claude Opus 5.5 (max) 89.9%; Moonshot AI: Kimi K3.1 Pro launch post (Terminal-Bench 4.0) (vendor-reported, Oct 23, 2026): Claude Opus 5.5 66.4%. Scores from different boards are not comparable with each other.

**Are Claude Opus 5.5 and GPT-6.1 Sol open source?** Claude Opus 5.5: Proprietary (API), no downloadable weights. GPT-6.1 Sol: Proprietary (API), no downloadable weights.

**Did you test Claude Opus 5.5 and GPT-6.1 Sol?** No. This page is Reported: every fact is read from the vendor page linked beside it, and benchmark numbers come from the named boards.

## How to cite

Agentic Weekly, "Claude Opus 5.5 vs GPT-6.1 Sol", updated 2026-10-29, https://theagenticweekly.com/compare/claude-opus-5-5-vs-gpt-6-1-sol