Claude Sonnet 5.5 vs Claude Opus 5.5
Claude Sonnet 5.5 is the lower-priced of the two on Router One — about 50% less on a 1M-input + 1M-output mix. Both carry a 1.05M context window. Both answer on /v1/chat/completions and /v1/messages (Claude Code).
Claude Sonnet 5.5 and Claude Opus 5.5 compared on current per-token rates, context window, and capabilities — both callable through one OpenAI-compatible endpoint with per-request cost traces.
Claude Sonnet 5.5 vs Claude Opus 5.5: rates, context window, and capabilities
| Spec | Claude Sonnet 5.5 | Claude Opus 5.5 |
|---|---|---|
| Input / 1M tokens | $1.20 | $2.40 |
| Output / 1M tokens | $6.00 | $12.00 |
| Cached input / 1M tokens | $0.12 | $0.40 |
| 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 | Claude Sonnet 5.5 | Claude Opus 5.5 |
What does 1M tokens cost on Claude Sonnet 5.5 vs Claude Opus 5.5?
For a workload of 1M input plus 1M output tokens at current rates: Claude Sonnet 5.5 comes to $7.20, Claude Opus 5.5 comes to $14.40 — Claude Sonnet 5.5 is about 50% 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 Claude Sonnet 5.5 and Claude Opus 5.5
The API key, base URL and endpoints stay the same, and per Anthropic's docs (checked 2026-09-30) both models default to adaptive thinking and reject forced tool use, but three things differ: of the two, only Claude Sonnet 5.5 accepts between_tools to turn up-front thinking off; the API's default effort is high on Sonnet 5.5 and medium on Opus 5.5, so set output_config.effort on /v1/messages instead of relying on the default; and neither model reads the other's thinking blocks, so a conversation that switches loses the earlier reasoning. Router One's compatibility rewrites for Opus 5.5 requests (see /blog/claude-opus-5-5-migration-guide) do not apply to Claude Sonnet 5.5. As of the 2026-09-30 plan response, both models are in no plan tier and bill the wallet per token.
curl https://api.router.one/v1/chat/completions \
-H "Authorization: Bearer sk-your-router-one-key" \
-H "Content-Type: application/json" \
-d '{"model": "anthropic/claude-sonnet-5.5", "messages": [{"role": "user", "content": "Hello"}]}'
# Same request, other model — change one string:
# "model": "anthropic/claude-opus-5.5"FAQ
Is Claude Sonnet 5.5 cheaper than Claude Opus 5.5?
Input: Claude Sonnet 5.5 $1.20 vs Claude Opus 5.5 $2.40 / 1M tokens; Claude Sonnet 5.5 has the lower rate. Output: Claude Sonnet 5.5 $6.00 vs Claude Opus 5.5 $12.00 / 1M tokens; Claude Sonnet 5.5 has the lower rate. Total cost depends on the workload's input, output and cache usage. Rates change; the /models page is the live source of truth.
Is Claude Sonnet 5.5 or Claude Opus 5.5 included in a Router One subscription?
Neither Claude Sonnet 5.5 nor Claude Opus 5.5 is in a Router One plan, so every call to either bills the wallet per token.
Can I switch between Claude Sonnet 5.5 and Claude Opus 5.5 without changing code?
The API key, base URL and endpoints stay the same, and per Anthropic's docs (checked 2026-09-30) both models default to adaptive thinking and reject forced tool use, but three things differ: of the two, only Claude Sonnet 5.5 accepts between_tools to turn up-front thinking off; the API's default effort is high on Sonnet 5.5 and medium on Opus 5.5, so set output_config.effort on /v1/messages instead of relying on the default; and neither model reads the other's thinking blocks, so a conversation that switches loses the earlier reasoning. Router One's compatibility rewrites for Opus 5.5 requests (see /blog/claude-opus-5-5-migration-guide) do not apply to Claude Sonnet 5.5. As of the 2026-09-30 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 2026-09-30 (UTC) and refresh within the hour.