Model Comparison
Claude Opus 4.8 vs GPT-5.5 InstantWhich is better in 2026?
Claude Opus 4.8 significantly outperforms across most benchmarks. Claude Opus 4.8 is 1.1x cheaper per token.
Verdict: Claude Opus 4.8 vs GPT-5.5 Instant — which is better?
Claude Opus 4.8 (by Anthropic) and GPT-5.5 Instant (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
Claude Opus 4.8 outperforms in 3 benchmarks (CharXiv-R, GPQA, HealthBench Professional), while GPT-5.5 Instant is better at 0 benchmarks. Claude Opus 4.8 significantly outperforms across most benchmarks.
On price, Claude Opus 4.8 is roughly 1.1x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Claude Opus 4.8 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose Claude Opus 4.8 if…
- you want the strongest raw capability — it leads on 3 of 3 shared benchmarks
- cost matters — it's about 1.1x cheaper per token
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped May 2026
Choose GPT-5.5 Instant if…
- you want predictable pricing at $5.00/M input and $30.00/M output
Performance Benchmarks
Comparative analysis across standard metrics
Claude Opus 4.8 outperforms in 3 benchmarks (CharXiv-R, GPQA, HealthBench Professional), while GPT-5.5 Instant is better at 0 benchmarks.
Claude Opus 4.8 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Opus 4.8 ($5.00/1M tokens) costs the same as GPT-5.5 Instant ($5.00/1M tokens).
For output processing, Claude Opus 4.8 ($25.00/1M tokens) is 1.2x cheaper than GPT-5.5 Instant ($30.00/1M tokens).
In conclusion, GPT-5.5 Instant is more expensive than Claude Opus 4.8.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Claude Opus 4.8 accepts 1,000,000 input tokens compared to GPT-5.5 Instant's 400,000 tokens. Both models can generate responses up to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both Claude Opus 4.8 and GPT-5.5 Instant support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Opus 4.8
GPT-5.5 Instant
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Claude Opus 4.8 was released on 2026-05-28, while GPT-5.5 Instant was released on 2026-05-05.
Claude Opus 4.8 is 1 month newer than GPT-5.5 Instant.
May 28, 2026
1 months ago
3w newerMay 5, 2026
2 months ago
Knowledge Cutoff
When training data ends
GPT-5.5 Instant has a documented knowledge cutoff of 2025-08-31, while Claude Opus 4.8's cutoff date is not specified.
We can confirm GPT-5.5 Instant's training data extends to 2025-08-31, but cannot make a direct comparison without Claude Opus 4.8's cutoff date.
—
Aug 2025
Provider Availability
Claude Opus 4.8 is available from Anthropic, Vertex AI. GPT-5.5 Instant is available from OpenAI.
Claude Opus 4.8
GPT-5.5 Instant
Outputs Comparison
Key Takeaways
Claude Opus 4.8
View detailsAnthropic
No standout differentiators in the data we have for this pair.
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Claude Opus 4.8 and GPT-5.5 Instant side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Claude Opus 4.8 vs GPT-5.5 Instant.