Claude Opus 4.6 has been the model many knowledge workers settled on since its February 2026 release. Reliable, excellent at writing, strong at code review, great document analysis. Then two things happened in the same week: Anthropic released Opus 4.7 on April 16, and OpenAI released GPT-5.5 on April 23. If you're still on Opus 4.6 and wondering whether to upgrade — or switch entirely — here's the honest comparison.
GPT-5.5 is a generational leap beyond Opus 4.6 for agentic tasks and computer use. For writing and document analysis, Opus 4.6 is still competitive — but Opus 4.7 is the natural upgrade path, not GPT-5.5.
How Does GPT-5.5 Compare to Opus 4.6 on Benchmarks?
| Benchmark | GPT-5.5 | Claude Opus 4.6 | Gap |
|---|---|---|---|
| SWE-bench Verified | — | 80.8% | — |
| Terminal-Bench 2.0 | 82.7% | 65.4% | GPT-5.5 +17.3 |
| GPQA Diamond | — | 91.3% | — |
| Context window | 1M | 1M | Tied |
| Output pricing | $30/1M | $25/1M | Opus 4.6 cheaper |
| Vision resolution | Standard | 1568px / 1.15MP | Similar |
The benchmark picture tells one story: GPT-5.5 has pulled significantly ahead on agentic coding tasks (Terminal-Bench 2.0 is a 17-point gap). But benchmarks don't capture everything. Opus 4.6 remains strong on structured reasoning, writing quality, and the kind of careful, precise work that many knowledge workers actually need day-to-day.
Where Does GPT-5.5 Clearly Beat Opus 4.6?
Agentic workflows: GPT-5.5 can handle messy, multi-part tasks — plan the approach, use tools, check its work, navigate ambiguity, and keep going. Opus 4.6 can do multi-step work, but it requires more hand-holding and is more likely to ask for clarification where GPT-5.5 just figures it out.
Computer use: GPT-5.5 can operate software, browse the web, interact with applications. This is a capability Opus 4.6 doesn't offer in the same way. If you need an AI that can actually click buttons and fill forms for you, GPT-5.5 is the only option.
Token efficiency: GPT-5.5 produces better results with fewer tokens than GPT-5.4 — and this efficiency advantage extends to the comparison with Opus 4.6. You get more useful output per API dollar.
If you switched to Opus 4.6 specifically for its writing quality and haven't been doing much agentic or coding work, GPT-5.5 probably isn't worth switching to. The writing gap still favors Claude. But if you've been wishing Opus 4.6 could "just do the task" without constant guidance, GPT-5.5 is what you've been waiting for.
Where Does Opus 4.6 Still Hold Up?
Writing quality: Opus 4.6's prose is still more natural and less formulaic than GPT-5.5's. For emails, reports, articles, and any content where the reader would notice generic phrasing, Claude remains the better writer.
Document analysis: The 200K+ context window with precise referencing makes Opus 4.6 excellent for reviewing contracts, analyzing reports, and extracting information from long documents. GPT-5.5 now matches the 1M context window, but Claude's referencing style tends to be more precise about where specific information comes from.
Price: Opus 4.6 is 17% cheaper on output tokens ($25 vs $30 per million). For high-volume API usage, this adds up.
Should You Upgrade to Opus 4.7 Instead?
If you're happy with Opus 4.6 and your work is writing-focused or document-focused, Opus 4.7 is the natural upgrade — not GPT-5.5. Anthropic describes Opus 4.7 as a direct improvement: same $5/$25 pricing, but with meaningfully better coding benchmarks (87.6% vs 80.8% on SWE-bench Verified), dramatically better vision (3.75MP vs 1.15MP), and a new ability to self-verify its outputs before reporting back.
The tradeoffs: Opus 4.7's new tokenizer uses 1–1.35x more tokens for the same input, and it follows instructions more literally, which means prompts you've tuned for Opus 4.6 may need adjustment.
The upgrade path depends on your work. Writing and documents → upgrade to Opus 4.7 (stay in the Claude ecosystem, better at what you already use it for). Agentic coding and automation → add GPT-5.5 (different capability, not a replacement). Both → use both.
What About Using Multiple Models?
This is increasingly the right answer. The knowledge workers getting the most out of AI in April 2026 aren't picking one model — they're routing tasks to whichever model handles them best.
The Practical Decision Framework
If you only write, analyze documents, and review code: Upgrade from Opus 4.6 to Opus 4.7. Skip GPT-5.5. You're not missing anything essential for your workflow.
If you build software or automate workflows: Add GPT-5.5 alongside Claude. The agentic capabilities are a genuine step-change that Claude doesn't match yet.
If you do both: Both subscriptions. Route by task type. This is the optimal setup for serious AI users in 2026, and the extra $20/month pays for itself in the first week.
Managing both platforms? Switching between ChatGPT and Claude multiple times per day creates its own friction — different conversation histories, different organization, different search. A cross-platform extension like TresPrompt adds folders and search to both from one tool, which helps keep the multi-model workflow organized.