Claude Opus 4.8 vs GPT-5.5 Instant (June 2026)
Head-to-head specifications
| Metric | Claude Opus 4.8 | GPT-5.5 Instant (June 2026) | Difference |
|---|---|---|---|
| Intelligence Index | 56.0 | 31.0 | +80.6% |
| Coding Index | 74.3 | 39.4 | +88.6% |
| Agentic Index | 47.2 | 11.0 | — |
| Context window | 1M tokens | 922K tokens | — |
| Blended price ($/1M tokens) | $1.38 | $1.55 | -11.0% |
| Access | Proprietary API | Proprietary API | — |
- Claude Opus 4.8 leads overall capability (Intelligence Index 56.0 vs 31.0).
- Claude Opus 4.8 is the cheaper model to run at $1.38/1M blended tokens — about 1.1× cheaper.
- Claude Opus 4.8 offers the larger context window (1M tokens), useful for long documents and codebases.
Verdict: Claude Opus 4.8 or GPT-5.5 Instant (June 2026)?
Claude Opus 4.8 advantages
- General intelligence (+45%)
- Coding ability (+47%)
- Agentic task performance (+77%)
- Context window (+8%)
- Affordability (+11%)
GPT-5.5 Instant (June 2026) advantages
- No decisive advantage on the tracked metrics.
Which should you choose?
- Choose the Claude Opus 4.8 if you need the strongest overall reasoning and accuracy.
- Choose the Claude Opus 4.8 if coding and software development are your main workload.
Value for money
Claude Opus 4.8 offers more intelligence per dollar (2.0× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use.
Claude Opus 4.8 vs GPT-5.5 Instant (June 2026): which should you choose?
Claude Opus 4.8 — Anthropic multimodal model with an Intelligence Index of 56, a 1M-token context window and a blended price of $1.38/1M tokens.
GPT-5.5 Instant (June 2026) — OpenAI multimodal model with an Intelligence Index of 31, a 922K-token context window and a blended price of $1.55/1M tokens.
Claude Opus 4.8 vs GPT-5.5 Instant (June 2026): Claude Opus 4.8 scores higher on the Intelligence Index. Claude Opus 4.8 leads overall capability (Intelligence Index 56.0 vs 31.0). Claude Opus 4.8 is the cheaper model to run at $1.38/1M blended tokens — about 1.1× cheaper.
Capability: intelligence, coding and agentic work
On the composite Intelligence Index the Claude Opus 4.8 scores 56.0 versus 31.0. For software development, the Coding Index puts Claude Opus 4.8 ahead (74.3 vs 39.4). On agentic, multi-step tool-use tasks, Claude Opus 4.8 measures stronger. Composite indices summarize many evaluations, but always test on your own workload before committing.
Context window and speed
The Claude Opus 4.8 accepts up to 1 million tokens per request, which sets how much documentation, transcript or code it can reason over at once.
Pricing and access
At blended per-token rates, Claude Opus 4.8 is the cheaper model to run ($1.38 vs $1.55 per 1M tokens). Claude Opus 4.8 is proprietary api and GPT-5.5 Instant (June 2026) is proprietary api. Open-weight models can be self-hosted, trading per-call cost for infrastructure you manage; for production also weigh rate limits, throughput and data-residency requirements.
The verdict
Both are credible choices in the ai model comparison space; the specification table above lays out every metric so you can weigh the trade-offs that matter to you. Pick the one whose strengths line up with how you will actually use it.
Frequently asked questions
Is the Claude Opus 4.8 better than the GPT-5.5 Instant (June 2026)?
Claude Opus 4.8 is the clearly stronger overall choice, winning most of the dimensions that matter. Claude Opus 4.8 leads overall capability (Intelligence Index 56.0 vs 31.0).
What is the main difference between the Claude Opus 4.8 and the GPT-5.5 Instant (June 2026)?
Claude Opus 4.8 leads overall capability (Intelligence Index 56.0 vs 31.0). Claude Opus 4.8 is the cheaper model to run at $1.38/1M blended tokens — about 1.1× cheaper.
Which is better value?
Claude Opus 4.8 offers more intelligence per dollar (2.0× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use.
Which should I choose?
Choose the Claude Opus 4.8 if you need the strongest overall reasoning and accuracy. Choose the Claude Opus 4.8 if coding and software development are your main workload.
Methodology
Large language models are compared on independent leaderboard metrics: an Intelligence Index (a composite of reasoning and knowledge evaluations), Coding and Agentic indices where measured, community arena Elo, maximum context window, a blended API price per million tokens (weighted across cache-hit, input and output rates), and measured output speed in tokens per second. Where a model ships multiple reasoning-effort variants, we report its strongest variant. Benchmarks capture only part of real-world quality, which also depends on tool use, latency, safety and task fit — and this space moves quickly, so figures reflect the leaderboard snapshot on the page date.