Claude Opus 4.8 vs GPT-5.5
GPT-5.5 is the lower-priced of the two on Router One — about 80% less on a 1M-input + 1M-output mix. Both carry a 1.05M context window. Claude Opus 4.8 answers on /v1/chat/completions and /v1/messages (Claude Code); GPT-5.5 on /v1/chat/completions and /v1/responses (Codex CLI).
Claude Opus 4.8 and GPT-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 Opus 4.8 vs GPT-5.5: rates, context window, and capabilities
| Spec | Claude Opus 4.8 | GPT-5.5 |
|---|---|---|
| Input / 1M tokens | $2.25 | $0.50 |
| Output / 1M tokens | $11.25 | $2.25 |
| Cached input / 1M tokens | $0.375 | $0.125 |
| Context window | 1.05M | 1.05M |
| Capabilities | Chat, Streaming, Tool calling, Vision | Chat, Streaming, Tool calling, Vision |
| Subscription plans | Premium models — Pro, Max, Ultra | Premium models — Pro, Max, Ultra |
| Detail page | Claude Opus 4.8 | GPT-5.5 |
What does 1M tokens cost on Claude Opus 4.8 vs GPT-5.5?
For a workload of 1M input plus 1M output tokens at current rates: Claude Opus 4.8 comes to $13.50, GPT-5.5 comes to $2.75 — GPT-5.5 is about 80% 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 Opus 4.8 and GPT-5.5
Both models answer on /v1/chat/completions, so an A/B test there is a one-string change — same key, same code, and every request traced with tokens, cost, and latency in the dashboard. Claude Code uses /v1/messages, which Router One lists for Claude Opus 4.8 but not GPT-5.5; Codex CLI uses /v1/responses, which Router One lists for GPT-5.5 but not Claude Opus 4.8 — so in those tools, switch the tool (or call /v1/chat/completions), not only the model string.
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-opus-4.8", "messages": [{"role": "user", "content": "Hello"}]}'
# Same request, other model — change one string:
# "model": "openai/gpt-5.5"FAQ
Is Claude Opus 4.8 cheaper than GPT-5.5?
Input: Claude Opus 4.8 $2.25 vs GPT-5.5 $0.50 / 1M tokens; GPT-5.5 has the lower rate. Output: Claude Opus 4.8 $11.25 vs GPT-5.5 $2.25 / 1M tokens; GPT-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 Opus 4.8 or GPT-5.5 included in a Router One subscription?
Claude Opus 4.8 and GPT-5.5 both count against the Premium models allowance on Pro, Max and Ultra: Pro 300, Max 1,000 and Ultra 5,000 requests per 30-day cycle, one pool shared by every model in that tier. Requests to Claude Opus 4.8 or GPT-5.5 above the model's long-context threshold count as more than one quota request. Requests beyond a plan's allowance bill the wallet per token.
Can I switch between Claude Opus 4.8 and GPT-5.5 without changing code?
On /v1/chat/completions, yes — change the model string; the key and base URL stay the same. Claude Code uses /v1/messages, which Router One lists for Claude Opus 4.8 but not GPT-5.5; Codex CLI uses /v1/responses, which Router One lists for GPT-5.5 but not Claude Opus 4.8 — so in those tools, switch the tool (or call /v1/chat/completions), not only the model string.
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 2026-10-15 (UTC) and refresh within the hour.