The AI arena is free today

Open Superagent

Claude Sonnet 5.5 vs GPT-6 Astra

Claude Sonnet 5.5 and GPT-6 Astra are closely matched at 51.5 and 59.3 on the LLM Stats Score. Claude Sonnet 5.5 is 5.0x cheaper per token.

Anthropic · OpenAI · Updated for 2026

Which is better?

Claude Sonnet 5.5 and GPT-6 Astra are closely matched on the overall LLM Stats Score at 51.5 and 59.3.

The models split the 2 individual benchmarks reported for both models evenly.

On price, Claude Sonnet 5.5 is roughly 5.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-6 Astra also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Sonnet 5.5

  • cost matters — it's about 5.0x cheaper per token
  • you want the most recent training data — it shipped Sep 2026

Choose GPT-6 Astra

  • you process long inputs — it offers a 1,050,000 token context window

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
GPT-6 Astra
OpenAI
Core performance indexes
LLM Stats Score
51.5
#12
59.3
#2
Reasoning
49.7
#16
57.1
#2
Coding
42.6
#7
48.7
#2
Agents
39.3
#9
45.7
#1
Cost, coverage & limits
Benchmark wins
1 of 2
1 of 2
Input price
$2.00 / M
$10.00 / M
Output price
$10.00 / M
$50.00 / M
Context window
1,000,000
1,050,000

Individual benchmarks

8 reported for Claude Sonnet 5.5 · 22 for GPT-6 Astra

2 shared

Claude Sonnet 5.5 outperforms in 1 benchmarks (Terminal-Bench 4.0), while GPT-6 Astra is better at 1 benchmark (FrontierCode 1.1).

Both models are evenly matched across the benchmarks.

Mon Sep 28 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

Claude Sonnet 5.5 costs less

For input processing, Claude Sonnet 5.5 ($2.00/1M tokens) is 5.0x cheaper than GPT-6 Astra ($10.00/1M tokens).

For output processing, Claude Sonnet 5.5 ($10.00/1M tokens) is 5.0x cheaper than GPT-6 Astra ($50.00/1M tokens).

In conclusion, GPT-6 Astra is more expensive than Claude Sonnet 5.5.*

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

Lowest available price from all providers
Mon Sep 28 2026 • llm-stats.com
Anthropic
Claude Sonnet 5.5
Input tokens$2.00
Output tokens$10.00
Best providerAnthropic
OpenAI
GPT-6 Astra
Input tokens$10.00
Output tokens$50.00
Best providerOpenAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-6 Astra accepts 1,050,000 input tokens compared to Claude Sonnet 5.5's 1,000,000 tokens. Both models can generate responses up to 128,000 tokens.

Anthropic
Claude Sonnet 5.5
Input1,000,000 tokens
Output128,000 tokens
OpenAI
GPT-6 Astra
Input1,050,000 tokens
Output128,000 tokens
Mon Sep 28 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Sonnet 5.5 and GPT-6 Astra support multimodal inputs.

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

Claude Sonnet 5.5

Text
Images
Audio
Video

GPT-6 Astra

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 Sonnet 5.5

Proprietary

Closed source

GPT-6 Astra

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while GPT-6 Astra was released on 2026-09-04.

Claude Sonnet 5.5 is 1 month newer than GPT-6 Astra.

Claude Sonnet 5.5

Sep 28, 2026

0 days ago

3w newer
GPT-6 Astra

Sep 4, 2026

3 weeks ago

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a knowledge cutoff of 2026-06-01, while GPT-6 Astra has a cutoff of 2026-04-30.

Claude Sonnet 5.5 has more recent training data (up to 2026-06-01), making it potentially better informed about events through that date compared to GPT-6 Astra (2026-04-30).

Claude Sonnet 5.5

Jun 2026

2 mo newer
GPT-6 Astra

Apr 2026

Provider Availability

Claude Sonnet 5.5 is available from Anthropic. GPT-6 Astra is available from OpenAI.

Claude Sonnet 5.5

anthropic logo
Anthropic
Input Price:Input: $2.00/1MOutput Price:Output: $10.00/1M

GPT-6 Astra

openai logo
OpenAI
Input Price:Input: $10.00/1MOutput Price:Output: $50.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and GPT-6 Astra side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
GPT-6 Astra
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs GPT-6 Astra.

Which is better, Claude Sonnet 5.5 or GPT-6 Astra?

Claude Sonnet 5.5 and GPT-6 Astra are closely matched on the LLM Stats Score at 51.5 and 59.3. Claude Sonnet 5.5 is made by Anthropic and GPT-6 Astra is made by OpenAI. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Sonnet 5.5 compare to GPT-6 Astra in benchmarks?

Claude Sonnet 5.5 scores OSWorld 2.1 (partial): 80.1%, Terminal-Bench 4.0: 70.6%, Humanity's Last Exam (with tools): 64.5%, Chartography (no tools): 61.6%, GDPval-AA 2.1: 61.5%. GPT-6 Astra scores ExploitBench: 100.0%, ARC-AGI-3: 99.9%, ARC-AGI: 98.5%, FrontierMath Tier 4 (v2): 97.6%, GPQA: 96.0%.

Is Claude Sonnet 5.5 cheaper than GPT-6 Astra?

Claude Sonnet 5.5 is 5.0x cheaper for input tokens. Claude Sonnet 5.5 costs $2.00/M input and $10.00/M output via anthropic. GPT-6 Astra costs $10.00/M input and $50.00/M output via openai.

What are the context window sizes for Claude Sonnet 5.5 and GPT-6 Astra?

Claude Sonnet 5.5 supports 1.0M tokens and GPT-6 Astra supports 1.1M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Sonnet 5.5 and GPT-6 Astra?

Key differences include LLM Stats Score (51.5 vs 59.3), context window (1.0M vs 1.1M), input pricing ($2.00 vs $10.00/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and GPT-6 Astra?

Claude Sonnet 5.5 is developed by Anthropic and GPT-6 Astra is developed by OpenAI.

Related comparisons