Claude Sonnet 5.5 vs GPT-6.1 Sol
Claude Sonnet 5.5 and GPT-6.1 Sol cost exactly the same: $2 input, $10 output and $0.10 cached input per 1M tokens. Their context windows are almost the same size, 1M and 1.05M tokens. What separates them is evidence: Sonnet 5.5 has published scores on three benchmarks, and we found none for GPT-6.1 Sol.
Identical prices, identical session costs
Because every rate matches, our three sessions cost the same to the cent: $0.65 for a quick fix, $10.80 for the feature session and $97.50 for a long agent day, or $2.59 for the feature session with 90% of prompts cached. Filling the whole window once costs $2.10 on GPT-6.1 Sol and $2.00 on Sonnet 5.5, only because the GPT window is larger.
What we can and can't compare
Sonnet 5.5 scored 70.6% on Terminal-Bench 4.0, 46.2% on FrontierCode 1.1 at max effort and 64.5% on Humanity's Last Exam with tools. There is no GPT-6.1 Sol score in our set, so the benchmark table shows "Not published" on its side.
They arrived a day apart. Anthropic released Sonnet 5.5 on 28 September 2026, and GPT-6.1 Sol was first listed on the API on 29 September.
How to choose
With the price a tie, the agent and the plan you already pay for decide more than the model: Claude models run in Claude Code and OpenAI's in Codex. Claude Code vs Codex sets the two tools side by side.
Side by side
| Claude Sonnet 5.5 | GPT-6.1 Sol | |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Released | 28 September 2026[1] | 29 September 2026[2] first API listing |
| Context window | 1M tokens[1] | 1.05M tokens[3] |
| Max output | 128K tokens[1] | 128K tokens[3] |
| Input price | $2 per 1M tokens[1] | $2 per 1M tokens[3] |
| Output price | $10 per 1M tokens[1] | $10 per 1M tokens[3] |
| Cached input | $0.10 per 1M tokens[4] | $0.10 per 1M tokens[3] |
| Long prompts | One price | One price |
| Price change | None announced | None announced |
| Open weights | No[1] Offered through the Claude API and cloud platforms; no weights are published. | No[5] Listed as an API model, not in OpenAI's open-weight section. |
| Reads | text, image[1] | text, image[3] |
Benchmarks
None of the benchmarks below has a published score for both models. We only show a score we can cite with its source and date; "Not published" means we found none for that model, not that it scored zero.
| Benchmark | Claude Sonnet 5.5 | GPT-6.1 Sol |
|---|---|---|
| Terminal-Bench 4.0Agentic coding tasks in a real terminal. | 70.6%[6] | Not published |
| FrontierCode 1.1 (Main)Hard software engineering tasks. | 46.2%[6] Max effort. | Not published |
| Humanity's Last Exam (with tools)Expert-level questions across many fields, tools allowed. | 64.5%[6] | Not published |
What a coding session costs
Our own estimate from the list prices above, for three sessions we define: a coding agent resends the conversation with every call, so prompts are large and grow. "Cached" assumes 90% of prompt tokens are read from the prompt cache and leaves out cache write fees. A long-prompt price applies when a call's prompt is over its threshold. Work out your own mix with the token cost calculator.
| Session | Claude Sonnet 5.5 | Claude Sonnet 5.5 cached | GPT-6.1 Sol | GPT-6.1 Sol cached |
|---|---|---|---|---|
| Quick fix10 calls of 25K prompt and 1.5K output tokens | $0.65 | $0.22 | $0.65 | $0.22 |
| Feature session60 calls of 80K prompt and 2K output tokens | $10.80 | $2.59 | $10.80 | $2.59 |
| Long agent day300 calls of 150K prompt and 2.5K output tokens | $97.50 | $20.55 | $97.50 | $20.55 |
Value for money and release gap
GPT-6.1 Sol is dated 1 day later (GPT-6.1 Sol: first API listing). Price per point divides our feature-session cost by a published score: lower means more score for the money. It is a rough lens, not a ranking.
| Measure | Claude Sonnet 5.5 | GPT-6.1 Sol |
|---|---|---|
| Input tokens per $1 | 500K | 500K |
| Filling the whole context window once | $2.00 | $2.10 |
Questions
Is GPT-6.1 Sol cheaper than Claude Sonnet 5.5?
No, they cost the same: $2 per 1M input tokens, $10 per 1M output tokens and $0.10 per 1M cached input tokens.
Which is better for coding, Sonnet 5.5 or GPT-6.1 Sol?
Sonnet 5.5 has a published Terminal-Bench 4.0 score of 70.6%; we have no score for GPT-6.1 Sol to set against it. Test both on your own tasks.
Which came out first?
Claude Sonnet 5.5, on 28 September 2026. GPT-6.1 Sol was first listed on the API a day later, on 29 September.
Most compared
Any other two models: pick them in the lists at the top of the page.
- Claude Opus 5.5 vs Claude Sonnet 5.5
- Claude Sonnet 5 vs Claude Sonnet 5.5
- Claude Haiku 5.5 vs Claude Sonnet 5.5
- Claude Opus 5.5 vs GPT-6.1 Sol
- GPT-6.1 Sol vs GPT-6 Sol
- GPT-6.1 Sol vs GPT-6 Astra
- Claude Sonnet 5.5 vs Gemini 4 Argon
- Gemini 4 Argon vs GPT-6.1 Sol
- Claude Sonnet 5.5 vs Kimi K3
- Claude Sonnet 5.5 vs GLM-5.3
- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Opus 5 vs Claude Opus 5.5
- Claude Haiku 4.5 vs Claude Haiku 5.5
- Claude Fable 5 vs Claude Fable 5.1
- Claude Opus 5.5 vs GPT-5.6 Sol
- Claude Fable 5.1 vs GPT-6 Astra
- Claude Opus 5.5 vs GPT-6 Astra
- Claude Haiku 5.5 vs GPT-6 Luna
- Claude Opus 5.5 vs Gemini 4 Argon
- Claude Opus 5.5 vs Gemini 3.1 Pro Preview
- Gemini 3.1 Pro Preview vs Gemini 4 Argon
- Claude Haiku 5.5 vs Gemini 3.8 Flash
- Claude Opus 5.5 vs Grok 4.7
- Claude Opus 5.5 vs DeepSeek V4 Pro
More tools
Sources
- platform.claude.com: docs/en/models/sonnet-5-5/overview, read
- openrouter.ai: openai/gpt-6.1-sol, read
- developers.openai.com: api/docs/models/gpt-6.1-sol, read
- platform.claude.com: docs/en/about-claude/pricing, read
- developers.openai.com: api/docs/models/all, read
- anthropic.com: claude-sonnet-5-5, read
Numbers from the makers' own pages, checked by hand, last read . List prices in US dollars before tax. Spotted a mistake? office@shuriken.sh.
Made by Shuriken, the harness for coding agents. Its hot swapping moves your chats to another of your accounts or API keys when one nears its limit. Use only accounts you own and are entitled to use.
Try Shuriken on your own computerYou're signed in
Add your Claude, Codex and Gemini accounts once. Shuriken switches between them so your agents keep working.Your accounts, projects and chats are in the app.
Coming soon