The Known Good Updated 2 Sep 2026 Subscribe
Anthropic: Claude Opus 4.5 vs OpenAI: o3 Mini ·Anthropic vs OpenAI

Anthropic: Claude Opus 4.5 vs OpenAI: o3 Mini — head-to-head comparison

Anthropic: Claude Opus 4.5 profile OpenAI: o3 Mini 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)
OpenAI: o3 Mini — OpenAI
Quality
#14 of 65
86based on 4 of 7 evaluations
Known Good Index
Speed
#16 of 339
142.5
Output tokens per second
Price
#301 of 439
$1.93
Blended per 1M tokens
In $1.10 · Out $4.40
Cache hit price
#302 of 322
$0.55
per 1M tokens (−50%)
Context
#321 of 473
200k
tokens (~300 pages)
Summary

On the Known Good Index, Anthropic: Claude Opus 4.5 scores 72 and OpenAI: o3 Mini scores 86 — a 13-point lead for OpenAI: o3 Mini. They share 2 published evaluations, with Anthropic: Claude Opus 4.5 ahead on 2 and OpenAI: o3 Mini ahead on 0.

Blended pricing is $10.00 per 1M tokens for Anthropic: Claude Opus 4.5 and $1.93 for OpenAI: o3 Mini — OpenAI: o3 Mini is about 5.2× cheaper.

Throughput is 47 tokens per second for Anthropic: Claude Opus 4.5 and 142 for OpenAI: o3 Mini, with time to first token at 1.4s and 2.8s. Anthropic: Claude Opus 4.5 accepts 200k tokens of context against 200k.

Anthropic: Claude Opus 4.5 is proprietary; OpenAI: o3 Mini is proprietary. 6 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 4.5OpenAI: o3 Mini
Known Good Index 72 based on 5 of 7 evaluations 86 based on 4 of 7 evaluations
Blended $/1M $10.00 $1.93
Output tok/s 47 142
Context window 200k 200k
Providers 5 1
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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 4.5OpenAI: o3 Mini
Known Good Index 72 86
Coding Index 80 —
Mathematics Index — 88
Reasoning Index 58 86
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 = OpenAI: o3 Mini · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond86 / 77
Mock AIME 2024–2586 / 77

Right-hand figures read Anthropic: Claude Opus 4.5 / OpenAI: o3 Mini. Anthropic: Claude Opus 4.5 leads on 2 of 2, OpenAI: o3 Mini on 0.

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 4.5OpenAI: o3 Mini
Text Arena 1,450 1,319
Text Arena (style controlled) 1,469 1,348
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 4.5OpenAI: o3 Mini
Input $/1M $5.00 $1.10
Output $/1M $25.00 $4.40
Blended $/1M $10.00 $1.93
Cache read $/1M $0.500 $0.550
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 4.5OpenAI: o3 Mini
Context window 200k 200k
Max output tokens 64k 100k
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 4.5OpenAI: o3 Mini
Output tokens/s 47 142
Time to first token 1.4s 2.8s
The Known Good

Providers

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

6 hosts
Full provider benchmarks →
Provider Anthropic: Claude Opus 4.5 blendedAnthropic: Claude Opus 4.5 tok/s OpenAI: o3 Mini blendedOpenAI: o3 Mini 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 — —
OpenAI · first party — — $1.93 150

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 →