GPT-5.5 vs Claude Sonnet 5
GPT-5.5 is the lower-priced of the two on Router One — about 49% less on a 1M-input + 1M-output mix. Both carry a 1.05M context window. GPT-5.5 answers on /v1/chat/completions and /v1/responses (Codex CLI); Claude Sonnet 5 on /v1/chat/completions and /v1/messages (Claude Code).
GPT-5.5 and Claude Sonnet 5 compared on current per-token rates, context window, and capabilities — both callable through one OpenAI-compatible endpoint with per-request cost traces.
GPT-5.5 vs Claude Sonnet 5: rates, context window, and capabilities
| Spec | GPT-5.5 | Claude Sonnet 5 |
|---|---|---|
| Input / 1M tokens | $0.50 | $0.90 |
| Output / 1M tokens | $2.25 | $4.50 |
| Cached input / 1M tokens | $0.125 | $0.15 |
| Context window | 1.05M | 1.05M |
| Capabilities | Chat, Streaming, Tool calling, Vision | Chat, Streaming, Tool calling, Vision |
| Detail page | GPT-5.5 | Claude Sonnet 5 |
What does 1M tokens cost on GPT-5.5 vs Claude Sonnet 5?
For a workload of 1M input plus 1M output tokens at current rates: GPT-5.5 comes to $2.75, Claude Sonnet 5 comes to $5.40 — GPT-5.5 is about 49% 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-5.5 and Claude Sonnet 5 without changing code
Both models are behind the same OpenAI-compatible endpoint, so an A/B test is a one-string change — same key, same code, and every request traced with tokens, cost, and latency in the dashboard:
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-5.5", "messages": [{"role": "user", "content": "Hello"}]}'
# Same request, other model — change one string:
# "model": "anthropic/claude-sonnet-5"FAQ
Is GPT-5.5 cheaper than Claude Sonnet 5?
At current posted rates, GPT-5.5 is the cheaper of the two (input $0.50 vs $0.90, output $2.25 vs $4.50 per 1M tokens). Rates change; the /models page is the live source of truth.
Can I switch between GPT-5.5 and Claude Sonnet 5 without changing code?
Yes. Both are served through the same OpenAI-compatible endpoint, so switching is changing the model string in the request — the key, base URL, and request shape stay identical.
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 2026-08-30 (UTC) and refresh within the hour.