GPT-5.5 vs Claude Opus 4.8
Side-by-side comparison of pricing, context window, modalities, licensing, and strengths — with practical guidance on which model fits which workload.
| Spec | GPT-5.5 | Claude Opus 4.8 |
|---|---|---|
| Provider | OpenAI | Anthropic |
| Context window | 1M tokens | 1M tokens |
| Input price (per 1M tokens) | $5.00 | $5.00 |
| Output price (per 1M tokens) | $30.00 | $25.00 |
| Example workload (10M in + 2M out) | $110.00 / month | $100.00 / month |
| Modalities | text, image, audio, code | text, image, code |
| Knowledge cutoff | Not disclosed | Not disclosed |
| Release date | 2026 | 2026 |
| License | Proprietary | Proprietary |
| Strengths | Flagship reasoning, Agentic tool use, Multimodal, Coding | Long-horizon agents, Coding, Knowledge work, Clear writing |
| Open weights | No | No |
Verdict
The 2026 flagship duel. Both models offer roughly 1M-token context windows and 128K output, but their pricing philosophies differ: Claude Opus 4.8 charges $5/$25 per million tokens flat, while GPT-5.5 costs $5/$30 — and bills prompts beyond 272K input tokens at 2× input / 1.5× output for the entire session, which matters enormously for long-context workloads. GPT-5.5 counters with native audio support and OpenAI’s vast ecosystem; Opus 4.8 is renowned for long-horizon agentic coding runs and clear, warm long-form writing.
When to choose GPT-5.5
Pick GPT-5.5 for audio-in workflows, the broadest third-party tooling ecosystem, and OpenAI-stack compatibility.
When to choose Claude Opus 4.8
Pick Claude Opus 4.8 for overnight agentic coding runs, long-document work without the long-context surcharge, and publication-quality writing.
Prices and specs reflect published provider information and change frequently — always confirm on the provider's pricing page before committing to a workload.
Frequently asked questions
Which is cheaper: GPT-5.5 or Claude Opus 4.8?
Claude Opus 4.8 is cheaper per token: $5.00 input / $25.00 output per 1M tokens, versus $5.00 / $30.00 for GPT-5.5. Actual costs depend on your input-to-output ratio — try the AI cost calculator for your own numbers.
Which has the larger context window?
GPT-5.5 supports 1M tokens versus 1M for Claude Opus 4.8 — roughly 1.1× more room for documents, code, and conversation history.
Can I self-host either model?
No — both models are proprietary and available only through their providers' APIs or cloud platforms.
How should I test which model is better for my use case?
Benchmarks are a starting point, not an answer. Run both models on 20–50 examples of your real task and compare outputs blind. Use our token counter to estimate prompt sizes and the cost calculator to project monthly spend before committing.