Model Comparison

GPT-5.5 Instant vs Grok 4.3Which is better in 2026?

Comparing GPT-5.5 Instant and Grok 4.3 across benchmarks, pricing, and capabilities.

Verdict: GPT-5.5 Instant vs Grok 4.3 — which is better?

GPT-5.5 Instant (by OpenAI) and Grok 4.3 (by xAI) 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.

On price, Grok 4.3 is roughly 7.2x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Grok 4.3 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose GPT-5.5 Instant if…

  • you want predictable pricing at $5.00/M input and $30.00/M output

Choose Grok 4.3 if…

  • cost matters — it's about 7.2x 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

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

GPT-5.5 Instant and Grok 4.3don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Grok 4.3 costs less

For input processing, GPT-5.5 Instant ($5.00/1M tokens) is 4.0x more expensive than Grok 4.3 ($1.25/1M tokens).

For output processing, GPT-5.5 Instant ($30.00/1M tokens) is 12.0x more expensive than Grok 4.3 ($2.50/1M tokens).

In conclusion, GPT-5.5 Instant is more expensive than Grok 4.3.*

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

Lowest available price from all providers
Fri Jul 17 2026 • llm-stats.com
OpenAI
GPT-5.5 Instant
Input tokens$5.00
Output tokens$30.00
Best providerOpenAI
xAI
Grok 4.3
Input tokens$1.25
Output tokens$2.50
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Grok 4.3 accepts 1,000,000 input tokens compared to GPT-5.5 Instant's 400,000 tokens. Only GPT-5.5 Instant specifies output context (128,000 tokens).

OpenAI
GPT-5.5 Instant
Input400,000 tokens
Output128,000 tokens
xAI
Grok 4.3
Input1,000,000 tokens
Output- tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

GPT-5.5 Instant supports multimodal inputs, whereas Grok 4.3 does not.

GPT-5.5 Instant can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-5.5 Instant

Text
Images
Audio
Video

Grok 4.3

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.

GPT-5.5 Instant

Proprietary

Closed source

Grok 4.3

Proprietary

Closed source

Release Timeline

When each model was launched

GPT-5.5 Instant was released on 2026-05-05, while Grok 4.3 was released on 2026-05-06.

Grok 4.3 is 0 month newer than GPT-5.5 Instant.

GPT-5.5 Instant

May 5, 2026

2 months ago

Grok 4.3

May 6, 2026

2 months ago

1d newer

Knowledge Cutoff

When training data ends

GPT-5.5 Instant has a documented knowledge cutoff of 2025-08-31, while Grok 4.3'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 Grok 4.3's cutoff date.

GPT-5.5 Instant

Aug 2025

Grok 4.3

—

Provider Availability

GPT-5.5 Instant is available from OpenAI. Grok 4.3 is available from xAI.

GPT-5.5 Instant

openai logo
OpenAI
Input Price:Input: $5.00/1MOutput Price:Output: $30.00/1M

Grok 4.3

xai logo
xAI
Input Price:Input: $1.25/1MOutput Price:Output: $2.50/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

OpenAI
Supports multimodal inputs
xAI
Larger context window (1,000,000 tokens)
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT-5.5 Instant and Grok 4.3 side-by-side, then vote on the output you prefer.

GPT-5.5 Instant
✓ Preferred
Grok 4.3
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT-5.5 Instant
xAI
Grok 4.3

FAQ

Common questions about GPT-5.5 Instant vs Grok 4.3.

Which is better, GPT-5.5 Instant or Grok 4.3?

GPT-5.5 Instant (OpenAI) and Grok 4.3 (xAI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does GPT-5.5 Instant compare to Grok 4.3 in benchmarks?

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%. Grok 4.3 scores Finance Agent v2: 37.7%, GDPval-AA: 36.7%.

Is GPT-5.5 Instant cheaper than Grok 4.3?

Grok 4.3 is 4.0x cheaper for input tokens. GPT-5.5 Instant costs $5.00/M input and $30.00/M output via openai. Grok 4.3 costs $1.25/M input and $2.50/M output via xai.

What are the context window sizes for GPT-5.5 Instant and Grok 4.3?

GPT-5.5 Instant supports 400K tokens and Grok 4.3 supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5.5 Instant and Grok 4.3?

Key differences include context window (400K vs 1.0M), input pricing ($5.00 vs $1.25/M), multimodal support (yes vs no). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5.5 Instant and Grok 4.3?

GPT-5.5 Instant is developed by OpenAI and Grok 4.3 is developed by xAI.

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