# GPT-6.1 Sol vs Claude Sonnet 5.5

> Markdown mirror of https://router.one/models/compare/gpt-6-1-sol-vs-claude-sonnet-5-5 for AI assistants and crawlers. Router One is a unified, OpenAI-compatible LLM API gateway.

GPT-6.1 Sol is the lower-priced of the two on Router One at base-tier rates (GPT-6.1 Sol: request input ≤ 272,000 tokens) — about 67% less on a 1M-input + 1M-output mix. Both carry a 1.05M context window. GPT-6.1 Sol answers on /v1/chat/completions and /v1/responses (Codex CLI); Claude Sonnet 5.5 on /v1/chat/completions and /v1/messages (Claude Code).

GPT-6.1 Sol and Claude Sonnet 5.5 compared on current per-token rates, context window, and capabilities — both callable through one OpenAI-compatible endpoint with per-request cost traces.

## GPT-6.1 Sol vs Claude Sonnet 5.5: rates, context window, and capabilities

| Spec | GPT-6.1 Sol | Claude Sonnet 5.5 |
| --- | --- | --- |
| Input / 1M tokens | $0.40 | $1.20 |
| Output / 1M tokens | $2.00 | $6.00 |
| Cached input / 1M tokens | $0.02 | $0.12 |
| Context window | 1.05M | 1.05M |
| Capabilities | Chat, Streaming, Tool calling, Vision | Chat, Streaming, Tool calling, Vision |
| Subscription plans | Not in any plan — wallet | Not in any plan — wallet |
| Detail page | [GPT-6.1 Sol](https://router.one/models/gpt-6-1-sol) | [Claude Sonnet 5.5](https://router.one/models/claude-sonnet-5-5) |

GPT-6.1 Sol: request input ≤ 272,000 tokens: Input $0.40 / 1M tokens, Output $2.00 / 1M tokens, Cache write $0.50 / 1M tokens, Cached input $0.02 / 1M tokens; request input > 272,000 tokens: Input $0.80 / 1M tokens, Output $3.00 / 1M tokens, Cache write $1.00 / 1M tokens, Cached input $0.04 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold.

## What does 1M tokens cost on GPT-6.1 Sol vs Claude Sonnet 5.5?

Base-tier rates: For a workload of 1M input plus 1M output tokens at current rates: GPT-6.1 Sol comes to $2.40, Claude Sonnet 5.5 comes to $7.20 — GPT-6.1 Sol is about 67% cheaper on this mix. Real workloads skew heavily toward input tokens, so weigh the input rate by your own ratio; the cached-input row above is the posted catalog rate for that model.

## Switch between GPT-6.1 Sol and Claude Sonnet 5.5

The API key and base URL stay the same, but this is not a one-string switch for every request. Per OpenAI's GPT-6 guide (checked 2026-10-01), GPT-6.1 Sol supports Chat Completions only for requests without tools, takes tool calls on the Responses API and takes no temperature, top_p or logprobs settings. Router One serves Claude Sonnet 5.5 on /v1/messages and /v1/chat/completions, not on /v1/responses. So code that sends tools has to change path as well as model: Codex CLI (/v1/responses) runs only the GPT side and Claude Code (/v1/messages) only the Claude side. As of the 2026-10-01 plan response, both models are in no plan tier and bill the wallet per token.

`compare.sh`

```bash
curl https://api.router.one/v1/chat/completions \
  -H "Authorization: Bearer sk-your-router-one-key" \
  -H "Content-Type: application/json" \
  -d '{"model": "openai/gpt-6.1-sol", "messages": [{"role": "user", "content": "Hello"}]}'

# Same request, other model — change one string:
#   "model": "anthropic/claude-sonnet-5.5"
```

## FAQ

### Is GPT-6.1 Sol cheaper than Claude Sonnet 5.5?

Compared at base-tier rates (GPT-6.1 Sol: request input ≤ 272,000 tokens). Input: GPT-6.1 Sol $0.40 vs Claude Sonnet 5.5 $1.20 / 1M tokens; GPT-6.1 Sol has the lower rate. Output: GPT-6.1 Sol $2.00 vs Claude Sonnet 5.5 $6.00 / 1M tokens; GPT-6.1 Sol has the lower rate. Total cost depends on the workload's input, output and cache usage. GPT-6.1 Sol: request input ≤ 272,000 tokens: Input $0.40 / 1M tokens, Output $2.00 / 1M tokens, Cache write $0.50 / 1M tokens, Cached input $0.02 / 1M tokens; request input > 272,000 tokens: Input $0.80 / 1M tokens, Output $3.00 / 1M tokens, Cache write $1.00 / 1M tokens, Cached input $0.04 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold. Rates change; the /models page is the live source of truth.

### Is GPT-6.1 Sol or Claude Sonnet 5.5 included in a Router One subscription?

Neither GPT-6.1 Sol nor Claude Sonnet 5.5 is in a Router One plan, so every call to either bills the wallet per token.

### Can I switch between GPT-6.1 Sol and Claude Sonnet 5.5 without changing code?

The API key and base URL stay the same, but this is not a one-string switch for every request. Per OpenAI's GPT-6 guide (checked 2026-10-01), GPT-6.1 Sol supports Chat Completions only for requests without tools, takes tool calls on the Responses API and takes no temperature, top_p or logprobs settings. Router One serves Claude Sonnet 5.5 on /v1/messages and /v1/chat/completions, not on /v1/responses. So code that sends tools has to change path as well as model: Codex CLI (/v1/responses) runs only the GPT side and Claude Code (/v1/messages) only the Claude side. As of the 2026-10-01 plan response, both models are in no plan tier and bill the wallet per token.

### Where do these numbers come from?

Specs and prices on this page render from the live Router One catalog — the same data as the /models page — and refresh with it. Pricing methodology is documented on /pricing-methodology. Rates on this page were read from the live catalog on 2026-10-01 (UTC) and refresh within the hour.

## More comparisons

- [Claude Sonnet 5.5 vs Claude Sonnet 5](https://router.one/models/compare/claude-sonnet-5-5-vs-claude-sonnet-5)
- [Claude Sonnet 5.5 vs Claude Opus 5.5](https://router.one/models/compare/claude-sonnet-5-5-vs-claude-opus-5-5)
- [GPT-6.1 Sol vs GPT-6 Sol](https://router.one/models/compare/gpt-6-1-sol-vs-gpt-6-sol)
- [GPT-6.1 Sol vs GPT-6 Astra](https://router.one/models/compare/gpt-6-1-sol-vs-gpt-6-astra)

## See also

- Canonical page: https://router.one/models/compare/gpt-6-1-sol-vs-claude-sonnet-5-5
- All model comparisons: https://router.one/models/compare
- All models & prices: https://router.one/models (markdown: https://router.one/models.md)
- Pricing: https://router.one/pricing
- GPT API access: https://router.one/cheap-gpt-api
- Claude API access: https://router.one/cheap-claude-api
- GPT-6.1 Sol API guide: https://router.one/blog/gpt-6-1-sol-api-guide
- Claude Sonnet 5.5 API guide: https://router.one/blog/claude-sonnet-5-5-api-guide
- Cost calculator: https://router.one/llm-cost-calculator
- Pricing methodology: https://router.one/pricing-methodology