The Known Good Updated 2 Sep 2026 Subscribe
Anthropic: Claude Opus 4.5 vs grok-4-0709 ·Anthropic vs xAI

Anthropic: Claude Opus 4.5 vs grok-4-0709 — head-to-head comparison

Anthropic: Claude Opus 4.5 profile grok-4-0709 profile All comparisons
Anthropic: Claude Opus 4.5 — Anthropic
Quality
#27 of 65
72based on 5 of 7 evaluations
Known Good Index
Speed
#176 of 339
47.0
Output tokens per second
Price
#409 of 439
$10.00
Blended per 1M tokens
In $5.00 · Out $25.00
Cache hit price
#299 of 322
$0.50
per 1M tokens (−90%)
Context
#314 of 473
200k
tokens (~300 pages)
grok-4-0709 — xAI
Quality
#32 of 65
68based on 3 of 7 evaluations
Known Good Index
Speed
unranked
Output tokens per second
Price
unranked
Blended per 1M tokens
Cache hit price
unranked
per 1M tokens
Context
unranked
tokens
Summary

On the Known Good Index, Anthropic: Claude Opus 4.5 scores 72 and grok-4-0709 scores 68 — a 4-point lead for Anthropic: Claude Opus 4.5. They share 3 published evaluations, with Anthropic: Claude Opus 4.5 ahead on 2 and grok-4-0709 ahead on 1.

Published pricing is tracked for Anthropic: Claude Opus 4.5 only, at $10.00 per 1M tokens blended.

Anthropic: Claude Opus 4.5 is proprietary; grok-4-0709 is proprietary. 5 tracked hosts serve one or both.

Generated from tracked data on 3 Sep 2026 · how these comparisons are computed →

At a glance
MetricAnthropic: Claude Opus 4.5grok-4-0709
Known Good Index 72 based on 5 of 7 evaluations 68 based on 3 of 7 evaluations
Blended $/1M $10.00
Output tok/s 47
Context window 200k
Providers 5 0
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Quality

Known Good Index and the capability indices, side by side

Index scores

Each index is min-max normalised across tracked models and scaled 0–100 from published evaluations. We do not run these evaluations.

MetricAnthropic: Claude Opus 4.5grok-4-0709
Known Good Index 72 68
Coding Index 80
Reasoning Index 58
Openness Index 5 5
The Known Good

Quality Breakdown

Every evaluation both models report a published score for

Evaluations both models report

Bar = Anthropic: Claude Opus 4.5 · marker = grok-4-0709 · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond86 / 87
Mock AIME 2024–2586 / 84
Terminal-Bench63 / 27

Right-hand figures read Anthropic: Claude Opus 4.5 / grok-4-0709. Anthropic: Claude Opus 4.5 leads on 2 of 3, grok-4-0709 on 1.

The Known Good

Arena Elo

Human preference rating from blind pairwise votes

Arena ratings

Elo from blind pairwise votes, ingested from Arena. Higher is better.

MetricAnthropic: Claude Opus 4.5grok-4-0709
Text Arena 1,450 1,411
Text Arena (style controlled) 1,469 1,411
The Known Good

Price & Cost

Published API pricing by token type

Published pricing

USD per 1M tokens. Blended is a 3:1 input:output mix. Live from OpenRouter, cross-checked against models.dev. Lower is better.

MetricAnthropic: Claude Opus 4.5grok-4-0709
Input $/1M $5.00
Output $/1M $25.00
Blended $/1M $10.00
Cache read $/1M $0.500
The Known Good
We publish blended price rather than cost-per-task. Cost-per-task requires token counts from an evaluation suite we do not run. Blended price is computed from published rates and is fully reproducible — see the pricing methodology.

Context Window

Maximum input accepted and maximum output emitted

Context and output limits

Provider-declared limits, from metadata via models.dev and OpenRouter. Higher is better.

MetricAnthropic: Claude Opus 4.5grok-4-0709
Context window 200k
Max output tokens 64k
The Known Good

Speed & Latency

Mean throughput and time to first token across hosting providers, over successful measurements from the last 48 hours

Throughput and latency

Means across all tracked providers over successful measurements from the last 48 hours, derived from OpenRouter endpoint telemetry.

MetricAnthropic: Claude Opus 4.5grok-4-0709
Output tokens/s 47
Time to first token 1.4s
The Known Good

Providers

Which hosts serve each model, and at what price and speed

5 hosts
Full provider benchmarks →
Provider Anthropic: Claude Opus 4.5 blendedAnthropic: Claude Opus 4.5 tok/s grok-4-0709 blendedgrok-4-0709 tok/s
Azure · first party $10.00 135
Amazon Bedrock · first party $10.00 87
Claude Platform on AWS $10.00 77
Anthropic · first party $10.00 40
Google · first party $10.00 5

Per-host pricing and telemetry from OpenRouter. A dash means that host does not serve that model.

The Known Good
Sources for this page
Pricing & providers — OpenRouter Metadata — models.dev Benchmarks — Epoch AI (CC-BY 4.0)Elo — Arena Full attribution →