Claude Opus 5.5 vs. GPT-6 Astra: A Comparative Analysis

This analysis evaluates the performance, cost, and technical capabilities of Anthropic’s Claude Opus 5.5 and OpenAI’s GPT-6 Astra. By examining benchmark data and operational metrics, we provide a clear framework for selecting the model best suited to your specific computational and reasoning requirements.

By the numbers

These figures describe the two model configurations shown here. A dash means the source snapshot had no usable figure for that metric. Scores, speed and API pricing may change as providers update models.

Metric	Claude Opus 5.5 (Adaptive Reasoning, Medium Effort, Default Fallback)	GPT-6 Astra (max)
Intelligence Index	51.2	52.7
Coding Index	–	76.9
Input price (per 1M tokens)	$4.00	$10.00
Output price (per 1M tokens)	$20.00	$50.00
Output speed (tokens/s)	77	58
Time to first token	11s	3.4 min
Release date	2026-09-17	2026-09-03

What the benchmarks show

When evaluating the cognitive capabilities of these two models, the data reveals distinct strengths. OpenAI’s GPT-6 Astra holds a slight lead in the overall intelligence index at 52.7, compared to the 51.2 index of Claude Opus 5.5. This advantage is further reflected in the GPQA benchmark, where GPT-6 Astra achieves a score of 0.961. While both models share an identical HLE score of 0.547, their performance diverges in specialized domains. Claude Opus 5.5 demonstrates a higher proficiency in scientific coding with a SciCode score of 0.593 against Astra’s 0.565, and it outperforms Astra in the LCR benchmark with a score of 0.843 compared to 0.807. Users should note that while GPT-6 Astra provides a documented coding index of 76.9, this metric remains unknown for Claude Opus 5.5, complicating a direct comparison of programming utility.

Speed and cost

Operational efficiency is a significant point of differentiation. Claude Opus 5.5 is optimized for rapid deployment, delivering an output speed of 76.787 tokens per second with a time-to-first-token of 11.136 seconds. This makes it highly responsive for interactive applications. In contrast, GPT-6 Astra exhibits a slower output speed of 57.943 tokens per second and a significantly higher time-to-first-token of 203.021 seconds, which may introduce noticeable friction in real-time workflows.

Financial considerations further highlight these differences. Claude Opus 5.5 is priced at a blended rate of $8.00 per million tokens, with input costs at $4.00 and output at $20.00. GPT-6 Astra is substantially more expensive, carrying a blended rate of $20.00 per million tokens, with input at $10.00 and output at $50.00. Organizations must weigh the marginal gains in intelligence index against the 2.5x cost increase associated with the OpenAI model.

Which model fits which workflow

Claude Opus 5.5 is best positioned for workflows that require high-frequency interaction and cost-effective scaling. Its low latency and superior performance in the LCR and SciCode benchmarks suggest it is well-suited for iterative development cycles and large-scale data processing tasks where budget constraints are a primary factor. The model’s adaptive reasoning and medium-effort default fallback settings provide a predictable, stable environment for standard enterprise operations.

GPT-6 Astra is better suited for specialized, high-complexity tasks that demand the highest possible intelligence index. Its performance on the GPQA benchmark indicates a capacity for deep, nuanced reasoning that may be necessary for research, complex problem solving, or tasks where the cost of an error outweighs the cost of the compute. However, users should be aware that the model’s opaque reasoning techniques have drawn scrutiny from safety experts, which may be a consideration for organizations with strict transparency or alignment requirements.

Decision takeaway

Selecting the right model requires balancing the immediate need for speed and cost-efficiency against the requirement for peak reasoning performance. Claude Opus 5.5 offers a balanced, high-velocity solution for most professional applications. GPT-6 Astra serves as a specialized instrument for the most demanding cognitive tasks, provided the user can accommodate the higher latency and increased financial investment.

FAQ

Is Claude Opus 5.5 Adaptive Reasoning better than GPT-6 Astra max?

It depends on what you need: GPT-6 Astra max scores higher on the intelligence index, 52.7 to 51.2; Claude Opus 5.5 Adaptive Reasoning is 60% cheaper on blended price; and Claude Opus 5.5 Adaptive Reasoning streams output 1.3 times as fast.

Is Claude Opus 5.5 Adaptive Reasoning or GPT-6 Astra max better at coding?

The catalogue has no coding index for Claude Opus 5.5 Adaptive Reasoning yet, so there is no direct coding comparison. The closest signal is the overall intelligence index, 51.2 for Claude Opus 5.5 Adaptive Reasoning and 52.7 for GPT-6 Astra max.

Which is cheaper, Claude Opus 5.5 Adaptive Reasoning or GPT-6 Astra max?

Claude Opus 5.5 Adaptive Reasoning is cheaper on a blended basis. Claude Opus 5.5 Adaptive Reasoning lists $4.00 per million input tokens and $20.00 per million output tokens; GPT-6 Astra max lists $10.00 and $50.00. For 1 million input and 200,000 output tokens that is $8.00 against $20.00.

When were Claude Opus 5.5 Adaptive Reasoning and GPT-6 Astra max released?

Claude Opus 5.5 Adaptive Reasoning is newer. It was released on September 17, 2026, 14 days after GPT-6 Astra max (September 3, 2026).

Which model has lower latency?

Claude Opus 5.5 Adaptive Reasoning generates output faster, at 77 tokens per second against 58 tokens per second. Claude Opus 5.5 Adaptive Reasoning reaches its first token sooner (11 seconds against 3.4 minutes).

Final whistle

Choosing between these models depends on your priority: throughput or raw intelligence. Claude Opus 5.5 is the superior choice for high-volume, latency-sensitive tasks due to its lower cost and faster response times. Conversely, GPT-6 Astra offers a higher intelligence index and superior performance on complex reasoning benchmarks like GPQA, making it the preferred tool for high-stakes, compute-intensive analysis where speed is a secondary concern.

Where the numbers come from

The scores, speed and prices in this comparison come from independent third-party model evaluations that Franklin AI syncs each day, and the article was written from a snapshot of them. For the latest results, open the Claude Opus 5.5 (Adaptive Reasoning, Medium Effort, Default Fallback) and GPT-6 Astra (max) pages. The AI Benchmark methodology explains how that data is collected and shown.