Claude Opus 5 vs GPT-6 Astra: a data-driven comparison

Side-by-side comparison

Criterion	Claude Opus 5	GPT-6 Astra
Developer	Anthropic	OpenAI
Released	July 24, 2026	September 4, 2026
Capability index	92.7 / 100	94.7 / 100
Input price	$5	$10
Output price	$25	$50
Cost of a typical task	$0.15	$0.30
Context window	1,000,000 tokens	1,050,000 tokens
Maximum output	128,000 tokens	128,000 tokens
Reasoning mode	Yes	Yes
Tool calling	Yes	Yes
Accepted inputs	text, image, PDF	text, image, PDF
Open weights	No	No
Knowledge cutoff	May 2026	April 30, 2026

The match-up at a glance

Claude Opus 5 and GPT-6 Astra are two frontier models, the ones you pick when quality comes first, one from Anthropic, the other from OpenAI. Claude Opus 5 was released on July 24, 2026, GPT-6 Astra on September 4, 2026.

All figures below come from public sources checked on October 22, 2026: models.dev and OpenRouter for prices and capabilities, Epoch AI for scores.

What the benchmarks say

On our capability index, Claude Opus 5 scores 92.7 out of 100 and GPT-6 Astra 94.7. GPT-6 Astra leads by 2 points.

On the 5 benchmarks reported for both, Claude Opus 5 wins 2 times and GPT-6 Astra 3:

GPQA Diamond (PhD-level science questions): Claude Opus 5 93.9%, GPT-6 Astra 95.8%
OTIS Mock AIME (competition mathematics problems): Claude Opus 5 98.9%, GPT-6 Astra 100%
FrontierMath (very hard research-level mathematics): Claude Opus 5 85.6%, GPT-6 Astra 93.7%
FrontierCode (advanced programming tasks): Claude Opus 5 53.4%, GPT-6 Astra 53.3%
APEX-Agents (professional tasks carried out by an agent): Claude Opus 5 65.8%, GPT-6 Astra 64.7%

Which one costs less?

Claude Opus 5 costs $5 per million input tokens and $25 per million output tokens; GPT-6 Astra costs $10 and $50.

For a typical agent task (read 20,000 tokens, write 2,000), expect $0.15 with Claude Opus 5 versus $0.30 with GPT-6 Astra. Claude Opus 5 is 2 times cheaper, a gap that adds up quickly over 1,000 tasks: $150 difference.

Run the numbers with your own volumes in the agent cost calculator.

Under the hood

GPT-6 Astra reads more in one go: 1,050,000 tokens of context (roughly 1,575 pages), versus 1,000,000 for Claude Opus 5.

Reasoning mode: Claude Opus 5 yes, GPT-6 Astra yes. Tool calling: Claude Opus 5 yes, GPT-6 Astra yes. Image input: Claude Opus 5 yes, GPT-6 Astra yes.

Neither publishes its weights: both are used through an API.

Knowledge cutoff: May 2026 for Claude Opus 5, April 30, 2026 for GPT-6 Astra.

In short

Our reading of the data:

Choose Claude Opus 5 for a lower cost.
Choose GPT-6 Astra for a higher capability index and a more recent release.

This verdict relies on public figures; it does not replace a trial on your own tasks.

Frequently asked questions

Claude Opus 5 or GPT-6 Astra: which is better?

On our index (Epoch AI data), Claude Opus 5 scores 92.7 and GPT-6 Astra 94.7 out of 100. The best choice also depends on price and on your use case.

Which one is cheaper?

Claude Opus 5. To read 20,000 tokens and write 2,000, expect $0.15 with Claude Opus 5 and $0.30 with GPT-6 Astra (prices as of October 22, 2026).

Which one has the larger context window?

GPT-6 Astra, with 1,050,000 tokens versus 1,000,000.

Can I run Claude Opus 5 or GPT-6 Astra on my own servers?

No: both are closed models, available through an API.

Claude Opus 5 vs GPT-6 Astra