Model Comparison

Claude Opus 4.5 vs GPT-5.5 InstantWhich is better in 2026?

Claude Opus 4.5 significantly outperforms across most benchmarks. Claude Opus 4.5 is 1.1x cheaper per token.

Verdict: Claude Opus 4.5 vs GPT-5.5 Instant — which is better?

Claude Opus 4.5 (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 4.5 outperforms in 1 benchmarks (GPQA), while GPT-5.5 Instant is better at 0 benchmarks. Claude Opus 4.5 significantly outperforms across most benchmarks.

On price, Claude Opus 4.5 is roughly 1.1x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-5.5 Instant also accepts a larger context window (400,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Claude Opus 4.5 if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
  • cost matters — it's about 1.1x cheaper per token

Choose GPT-5.5 Instant if…

  • you process long inputs — it offers a 400,000 token context window
  • you want the most recent training data — it shipped May 2026
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Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

Claude Opus 4.5 outperforms in 1 benchmarks (GPQA), while GPT-5.5 Instant is better at 0 benchmarks.

Claude Opus 4.5 significantly outperforms across most benchmarks.

Sun Jun 21 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Claude Opus 4.5 costs less

For input processing, Claude Opus 4.5 ($5.00/1M tokens) costs the same as GPT-5.5 Instant ($5.00/1M tokens).

For output processing, Claude Opus 4.5 ($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 4.5.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Sun Jun 21 2026 • llm-stats.com
Anthropic
Claude Opus 4.5
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
OpenAI
GPT-5.5 Instant
Input tokens$5.00
Output tokens$30.00
Best providerOpenAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-5.5 Instant accepts 400,000 input tokens compared to Claude Opus 4.5's 200,000 tokens. GPT-5.5 Instant can generate longer responses up to 128,000 tokens, while Claude Opus 4.5 is limited to 64,000 tokens.

Anthropic
Claude Opus 4.5
Input200,000 tokens
Output64,000 tokens
OpenAI
GPT-5.5 Instant
Input400,000 tokens
Output128,000 tokens
Sun Jun 21 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Claude Opus 4.5 and GPT-5.5 Instant support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Opus 4.5

Text
Images
Audio
Video

GPT-5.5 Instant

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Opus 4.5

Proprietary

Closed source

GPT-5.5 Instant

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Opus 4.5 was released on 2025-11-24, while GPT-5.5 Instant was released on 2026-05-05.

GPT-5.5 Instant is 5 months newer than Claude Opus 4.5.

Claude Opus 4.5

Nov 24, 2025

6 months ago

GPT-5.5 Instant

May 5, 2026

1 months ago

5mo newer

Knowledge Cutoff

When training data ends

Claude Opus 4.5 has a knowledge cutoff of 2025-03-31, while GPT-5.5 Instant has a cutoff of 2025-08-31.

GPT-5.5 Instant has more recent training data (up to 2025-08-31), making it potentially better informed about events through that date compared to Claude Opus 4.5 (2025-03-31).

Claude Opus 4.5

Mar 2025

GPT-5.5 Instant

Aug 2025

5 mo newer

Provider Availability

Claude Opus 4.5 is available from Anthropic. GPT-5.5 Instant is available from OpenAI.

Claude Opus 4.5

anthropic logo
Anthropic
Input Price:Input: $5.00/1MOutput Price:Output: $25.00/1M

GPT-5.5 Instant

openai logo
OpenAI
Input Price:Input: $5.00/1MOutput Price:Output: $30.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Less expensive output tokens
Higher GPQA score (87.0% vs 85.6%)
OpenAI
Larger context window (400,000 tokens)

Detailed Comparison

AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.5
OpenAI
GPT-5.5 Instant

FAQ

Common questions about Claude Opus 4.5 vs GPT-5.5 Instant.

Which is better, Claude Opus 4.5 or GPT-5.5 Instant?

Claude Opus 4.5 significantly outperforms across most benchmarks. Claude Opus 4.5 is made by Anthropic and GPT-5.5 Instant is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Claude Opus 4.5 compare to GPT-5.5 Instant in benchmarks?

Claude Opus 4.5 scores Tau2 Telecom: 98.2%, MMMLU: 90.8%, Tau2 Retail: 88.9%, GPQA: 87.0%, SWE-Bench Verified: 80.9%. GPT-5.5 Instant scores HealthBench Consensus: 94.7%, OmniDocBench 1.5: 87.5%, GPQA: 85.6%, CharXiv-R: 81.6%, AIME 2025: 81.2%.

Is Claude Opus 4.5 cheaper than GPT-5.5 Instant?

Both models cost $5.00 per million input tokens.

What are the context window sizes for Claude Opus 4.5 and GPT-5.5 Instant?

Claude Opus 4.5 supports 200K tokens and GPT-5.5 Instant supports 400K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Opus 4.5 and GPT-5.5 Instant?

Key differences include context window (200K vs 400K). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Opus 4.5 and GPT-5.5 Instant?

Claude Opus 4.5 is developed by Anthropic and GPT-5.5 Instant is developed by OpenAI.

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