Head-to-head comparison

Claude Opus 4.5 vs. GPT-6 Astra

Compare published benchmark results from matching versions and cohorts, API pricing, and technical specifications. Any documented test setup differences remain visible.

shared result series: 7
distinct benchmark metrics: 3
latest retrieval: 2026-10-16

First modelSecond model

Specifications

General specifications

Release date, availability, context window, architecture, and published parameter counts at a glance. Undisclosed details remain marked as unavailable.

Specifications for Claude Opus 4.5 and GPT-6 Astra
Attribute	Claude Opus 4.5	GPT-6 Astra
Provider	Anthropic	OpenAI
Released	Nov 2025	Sep 3, 2026
Availability	Active	Limited access
Model type	Proprietary	Proprietary
Parameters	Not published	Not published
Architecture	Not published	Not published
Context window	200,000 tokens	1,050,000 tokens
Knowledge cutoff	May 2025	April 30, 2026
Technical sources	Model, Context	Model, Context

Pricing

API pricing compared

The table compares official standard API rates per 1M tokens, including published cache pricing. Batch, fast, priority, regional surcharges, tool calls, and cloud platform pricing are excluded.

API pricing for Claude Opus 4.5 and GPT-6 Astra
Price type	Claude Opus 4.5	GPT-6 Astra
API input	$5	$10 ≤272K / $20 >272K
API output	$25	$50 ≤272K / $75 >272K
Cache read	$0.5	$1 ≤272K / $2 >272K
Cache write (5 min.)	$6.25	$12.5 ≤272K / $25 >272K
Cache write (1 hr.)	$10	Not listed
Price verified	09/22/2026 Source	09/22/2026 Source

Claude Opus 4.5GPT-6 Astra

API inputUSD per 1M tokens, base tier

Claude Opus 4.5$5

GPT-6 Astra$10

API outputUSD per 1M tokens, base tier

Claude Opus 4.5$25

GPT-6 Astra$50

Cache readUSD per 1M tokens, base tier

Claude Opus 4.5$0.5

GPT-6 Astra$1

Key to the marks:better valuebetter, but not conclusivetie

Pricing by provider

Direct developer pricing and provider endpoint tariffs routed through OpenRouter are listed separately. Prices are in USD per 1M tokens. Context-dependent direct tiers plus regional, Flex, Priority, and other OpenRouter tariffs remain individually identifiable.

Provider pricing for Claude Opus 4.5 and GPT-6 Astra
Model	Provider	Purchase route and tariff	Input per 1M tokens	Output per 1M tokens	Source
Claude Opus 4.5	Anthropic	Direct from developerStandard API	Lowest listed price: $5	Lowest listed price: $25	Source09/22/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock	Lowest listed price: $5	Lowest listed price: $25	Source10/26/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/eu-west-1	$5.5	$27.5	Source10/26/2026
	Anthropic	Via OpenRouteranthropic	Lowest listed price: $5	Lowest listed price: $25	Source10/26/2026
	Azure	Via OpenRouterazure/global	Lowest listed price: $5	Lowest listed price: $25	Source10/26/2026
	Claude Platform on AWS	Via OpenRouterclaude-on-aws	Lowest listed price: $5	Lowest listed price: $25	Source10/26/2026
	Google	Via OpenRoutergoogle-vertex/global	Lowest listed price: $5	Lowest listed price: $25	Source10/26/2026
GPT-6 Astra	OpenAI	Direct from developerUp to 272,000 context tokens	$10	$50	Source09/22/2026
	OpenAI	Direct from developerAbove 272,000 context tokens	$20	$75	Source09/22/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/us-west-2	$11	$55	Source10/26/2026
	Azure	Via OpenRouterazure	$10	$50	Source10/26/2026
	Azure	Via OpenRouterazure/us	$11	$55	Source10/26/2026
	OpenAI	Via OpenRouteropenai	$10	$50	Source10/26/2026
	OpenAI	Via OpenRouteropenai/fast	$20	$100	Source10/26/2026
	OpenAI	Via OpenRouteropenai/flex	Lowest listed price: $5	Lowest listed price: $25	Source10/26/2026
	OpenAI	Via OpenRouteropenai/ultrafast	$60	$300	Source10/26/2026

Benchmark index

Benchmark index compared

The index combines independent benchmarks on a scale from 0 to 100. A lead only counts when a model comes first in at least 95% of 200 recalculations with randomly redrawn test families. Otherwise both count as level.

Open the AI leaderboard

Claude Opus 4.5

Overall index

12.1

GPT-6 Astra

Overall index

90.0

GPT-6 Astra leads in 9 of 9 shared areas.

Area	Claude Opus 4.5	GPT-6 Astra
Coding	8.1	93.4
Reasoning	7.0	91.3
Knowledge	10.8	94.3
Agents	12.3	83.7
Finance	19.8	71.9
Legal	15.3	78.9
Health	19.6	83.8
Multimodal	10.4	91.7
Education	17.1	88.0

Performance

Shared benchmarks

Only published results with the same benchmark version, task, metric, and comparison cohort are paired. Different reasoning levels, agents, harnesses, or output limits appear directly in the table.

Capability profile from matched benchmarks

Each axis averages directly matched benchmark families. A value of 100 means the stronger value within this pair, not a universal quality score.

Not enough directly matched categories for a reliable radar

Only 0 of at least 5 categories have comparable, direct model measurements. The benchmark tables below show the available evidence without filling missing axes.

Claude Opus 4.5GPT-6 Astra

MedCodeOverall. Higher is better. Test setup not documented as identical

Claude Opus 4.545.174 %

GPT-6 Astra48.486 %

MedScribeOverall. Higher is better. Test setup not documented as identical

Claude Opus 4.583.246 %

GPT-6 Astra87.908 %

SAGEOverall. Higher is better. Test setup not documented as identical

Claude Opus 4.545.002 %

GPT-6 Astra46.367 %

SAGEAutomata. Higher is better. Test setup not documented as identical

Claude Opus 4.529.365 %

GPT-6 Astra37.302 %

SAGECalculus. Higher is better. Test setup not documented as identical

Claude Opus 4.558.333 %

GPT-6 Astra79.938 %

SAGELinear Algebra. Higher is better. Test setup not documented as identical

Claude Opus 4.564.372 %

GPT-6 Astra62.117 %

SAGEPartial Differential Equations. Higher is better. Test setup not documented as identical

Claude Opus 4.541.27 %

GPT-6 Astra39.683 %

Key to the marks:better valuebetter, but not conclusivetie

Benchmark scores for Claude Opus 4.5 and GPT-6 Astra
Benchmark and task	Claude Opus 4.5	GPT-6 Astra	Source
MedCodeOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Opus 4.5: Snapshot: claude-opus-4-5-20251101, Compute: high, Temperature: 1, Output limit: 30,000 tokens GPT-6 Astra: Reasoning: max, Output limit: 128,000 tokens	45.174 %	Higher measured value48.486 %	Vals AI Source details Data as of: 10/13/2026
MedScribeOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Opus 4.5: Snapshot: claude-opus-4-5-20251101, Compute: high, Temperature: 1, Output limit: 30,000 tokens GPT-6 Astra: Reasoning: max, Output limit: 128,000 tokens	83.246 %	Higher measured value87.908 %	Vals AI Source details Data as of: 10/13/2026
SAGEOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Opus 4.5: Snapshot: claude-opus-4-5-20251101, Compute: high, Temperature: 1, Output limit: 30,000 tokens GPT-6 Astra: Reasoning: max, Output limit: 30,000 tokens	45.002 %	Higher measured value46.367 %	Vals AI Source details Data as of: 10/08/2026
SAGEAutomata Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Opus 4.5: Snapshot: claude-opus-4-5-20251101, Compute: high, Temperature: 1, Output limit: 30,000 tokens GPT-6 Astra: Reasoning: max, Output limit: 30,000 tokens	29.365 %	Higher measured value37.302 %	Vals AI Source details Data as of: 10/08/2026
SAGECalculus Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Opus 4.5: Snapshot: claude-opus-4-5-20251101, Temperature: 1, Output limit: 30,000 tokens GPT-6 Astra: Reasoning: max, Output limit: 30,000 tokens	58.333 %	Higher measured value79.938 %	Vals AI Source details Data as of: 10/08/2026
SAGELinear Algebra Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Opus 4.5: Snapshot: claude-opus-4-5-20251101, Compute: high, Temperature: 1, Output limit: 30,000 tokens GPT-6 Astra: Reasoning: max, Output limit: 30,000 tokens	Higher measured value64.372 %	62.117 %	Vals AI Source details Data as of: 10/08/2026
SAGEPartial Differential Equations Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Opus 4.5: Snapshot: claude-opus-4-5-20251101, Compute: high, Temperature: 1, Output limit: 30,000 tokens GPT-6 Astra: Reasoning: max, Output limit: 30,000 tokens	Higher measured value41.27 %	39.683 %	Vals AI Source details Data as of: 10/08/2026
Key to the marks:better valuebetter, but not conclusivetie

Our model tests

Our tests

SVG short test

One SVG prompt and fixed output settings. Captures are shown only with 0 reported reasoning tokens or documented lack of reasoning controls. Identical test conditions do not make the models' internal compute identical.

Shared test round: 43b8c5c46830

Claude Opus 4.5

Unavailable in this round

GPT-6 Astra

Unavailable in this round

Earlier tests

Pelican on a bicycle

A community classic for free-form SVG drawing.

Claude Opus 4.5

Reasoning (requested): high

Current attempt

Run date: Oct 1, 2026
API provider: openrouter
Requested API model: anthropic/claude-opus-4.5
API model reported in response: anthropic/claude-opus-4.5
Reasoning setting: high
Pinned endpoint: Anthropic | anthropic/claude-4.5-opus-20251124
Temperature: Provider default
Token limit including reasoning: 8,192 tokens
Test protocol: community-visual-tests-v1
Technical checks: Passed, not a quality rating
Response time: 21.6 s

Visually reviewed. This individual test does not establish overall model quality.

GPT-6 Astra

Reasoning (requested): high

Current attempt

Run date: Sep 7, 2026
API provider: openrouter
Requested API model: openai/gpt-6-astra
API model reported in response: openai/gpt-6-astra
Reasoning setting: high
Pinned endpoint: OpenAI | openai/gpt-6-astra-20260903
Temperature: Provider default
Token limit including reasoning: 8,192 tokens
Test protocol: community-visual-tests-v1
Technical checks: Passed, not a quality rating
Response time: 141.7 s

Visually reviewed. This individual test does not establish overall model quality.

Prompt and test conditions

Generate an SVG of a pelican riding a bicycle

Token limit including reasoning: 8,192 tokens

Task origin (Simon Willison)

How to read this comparison

Winning one benchmark is not an overall verdict

Your workload, budget, and required context length matter most. A coding benchmark says little about visual understanding or agent performance.

The standard price table uses direct developer rates. The provider comparison labels OpenRouter endpoints, regions, and special tariffs separately.

Every result links to its measurement source and retrieval date. Labels distinguish vendor reports, official benchmark leaderboards, and independent evaluations. Disputed or archived results are excluded.

More matchups

Compare Claude Opus 4.5 and GPT-6 Astra with other leading models using the same data and benchmark logic.

View the complete LLM comparison

Claude Opus 4.5 vs. GPT-6 Astra

Change model selection

General specifications

API pricing compared

Benchmark index compared

Shared benchmarks

Capability profile from matched benchmarks

Our tests

SVG short test

Claude Opus 4.5

GPT-6 Astra

Pelican on a bicycle

Winning one benchmark is not an overall verdict

Related LLM comparisons