Claude Opus 4.6 vs GPT-5.5
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Opus 4.6 for agentic coding and debugging in large codebases or long-running, multi-step autonomous agent tasks. Pick GPT-5.5 for terminal, cli and computer-use automation or long-horizon tool sequencing.
Claude Opus 4.6 (Anthropic) and GPT-5.5 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Opus 4.6 is anthropic's February 2026 flagship Opus and the first Opus-class model with a 1M-token context window, built for agentic coding and long-running professional tasks. GPT-5.5 is openAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. The breakdown below works through their capabilities and ideal use cases so you can match one to your task.
Key differences at a glance
- ▸Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
- ▸Recency: GPT-5.5 is the newer model by about 3 months (released April 23, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | Claude Opus 4.6 | GPT-5.5 |
|---|---|---|
| Provider | Anthropic (US) | OpenAI (US) |
| Released | February 5, 2026 | April 23, 2026 |
| Context window | 1M (~1,500 pages) | 1M (~1,500 pages) |
| Price (in/out) | $5/$25 per 1M tokens | $5/$30 per 1M tokens |
| Open weight? | No — API only | No — API only |
| Modalities | text, image, code | text, image, code |
| SWE-Bench Verified | 80.8% | Not published |
| MRCR v2 @ 1M | 76% | Not published |
Who wins what
Agentic coding and debugging in large codebases
Claude Opus 4.6
GPT-5.5 is comparatively weak here — trails Opus 4.8 on hardest coding benchmarks
Long-running, multi-step autonomous agent tasks
Claude Opus 4.6
Claude Opus 4.6 lists long-running, multi-step autonomous agent tasks among its strengths; GPT-5.5 does not.
Frontier multidisciplinary reasoning (leads Humanity's Last Exam)
Claude Opus 4.6
Claude Opus 4.6 lists frontier multidisciplinary reasoning (leads Humanity's Last Exam) among its strengths; GPT-5.5 does not.
Terminal, CLI and computer-use automation
GPT-5.5
OpenAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion — and it is the newer of the two.
Long-horizon tool sequencing
GPT-5.5
GPT-5.5 lists long-horizon tool sequencing among its strengths; Claude Opus 4.6 does not.
Strong agentic coding and reasoning
GPT-5.5
GPT-5.5 lists strong agentic coding and reasoning among its strengths; Claude Opus 4.6 does not.
Which should you pick?
Anyone whose priority is agentic coding and debugging in large codebases
→ Claude Opus 4.6
It is specifically built for that.
Anyone whose priority is terminal, cli and computer-use automation
→ GPT-5.5
That is its strongest area.
Claude Opus 4.6: where it fits
Anthropic's February 2026 flagship Opus and the first Opus-class model with a 1M-token context window, built for agentic coding and long-running professional tasks. Released February 5, 2026 by Anthropic, it is built for agentic coding and debugging in large codebases, long-running, multi-step autonomous agent tasks, frontier multidisciplinary reasoning (leads Humanity's Last Exam), and economically valuable knowledge work in finance and legal (GDPval-AA).
Its trade-offs are real: superseded by newer Claude Opus 4.7 and 4.8 (now a legacy model), and top-tier per-token price, and its 1M-token context shipped as beta. At $5 in / $25 out per million tokens, it sits in the premium price band.
GPT-5.5: where it fits
OpenAI's first fully retrained base since GPT-4.5 — the terminal and computer-use champion. Released April 23, 2026 by OpenAI, it is built for terminal, CLI and computer-use automation, long-horizon tool sequencing, strong agentic coding and reasoning, and browser-driving agents.
Its trade-offs: trails Opus 4.8 on hardest coding benchmarks, and tiered long-context pricing above 272K tokens. At $5 in / $30 out per million tokens, it sits in the premium price band.
The bottom line for this matchup
Claude Opus 4.6 and GPT-5.5 overlap enough that the right pick depends on your specific job. and each leads in its own area — Claude Opus 4.6 for agentic coding and debugging in large codebases, GPT-5.5 for terminal, cli and computer-use automation. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Opus 4.6 and GPT-5.5 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
See pricingFrequently asked questions
Is Claude Opus 4.6 or GPT-5.5 better for coding?
Public SWE-Bench figures are not available for GPT-5.5, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 4.6 leans toward agentic coding and debugging in large codebases while GPT-5.5 leans toward terminal, cli and computer-use automation, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Opus 4.6 or GPT-5.5?
They are priced almost identically, so cost will not decide between them.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Can I use both Claude Opus 4.6 and GPT-5.5 together?
Yes — a multi-model platform like LumiChats gives you Claude Opus 4.6, GPT-5.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Opus 4.6 or GPT-5.5?
GPT-5.5 — released April 23, 2026, about 3 months after Claude Opus 4.6.
Related comparisons
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.