Jul 27, 2026 · 7 min read

Claude Opus 5: The Complete Guide to Anthropic's Most Capable Model

Claude Opus 5 launched on July 24, 2026, and it represents a generational leap in AI capability. Scoring 43.3% on Frontier-Bench (doubling its predecessor) and tripling the next best model on ARC-AGI 3, Opus 5 is not just an incremental update. It is a fundamentally more capable system that Anthropic has designed for daily professional use.

This guide covers everything you need to know about Claude Opus 5: specifications, benchmarks, pricing, effort levels, API integration, and practical use cases.

Core Specifications

Here are the key technical details for Claude Opus 5:

Model ID: claude-opus-5
Context window: 1,000,000 tokens
Maximum output: 128,000 tokens
Input pricing: $5 per million tokens
Output pricing: $25 per million tokens
Fast mode: $10/$50 per million tokens at 2.5x speed
Thinking: On by default with 5-level effort control
Release date: July 24, 2026

The 1M context window paired with 128K max output makes Opus 5 suitable for processing entire codebases, long documents, and complex multi-step workflows without truncation. If you are coming from Opus 4.8, the context window remains the same, but output quality has improved dramatically.

Benchmark Performance

Opus 5 does not just beat its predecessor. It redefines what frontier models can achieve across multiple categories.

Frontier-Bench: 43.3%

This is the headline number. Opus 5 scores 43.3% on Frontier-Bench, which doubles the score achieved by Opus 4.8 and significantly surpasses Fable 5’s 33.7%. Frontier-Bench measures novel problem-solving on tasks that have never appeared in training data, making this result particularly impressive.

ARC-AGI 3: 3x the Next Best Model

On ARC-AGI 3, which tests abstract reasoning and pattern recognition, Opus 5 triples the score of the next best model. This benchmark is designed to be resistant to memorization and requires genuine generalization ability.

CursorBench 3.2: Within 0.5% of Fable 5

For coding tasks specifically, Opus 5 performs within 0.5% of Fable 5 on CursorBench 3.2. Given that Fable 5 costs twice as much ($10/$50 vs $5/$25), this makes Opus 5 the clear value leader for software development. Check our best AI coding tools guide for how this fits into the broader landscape.

OSWorld 2.0: Best at Any Cost

Opus 5 beats every other model on OSWorld 2.0 regardless of price tier. It surpasses Fable 5 at one-third the effective cost when factoring in the tasks where Fable 5 needs multiple attempts.

GDPval-AA v2: State of the Art

On GDPval-AA v2, which measures alignment and value adherence, Opus 5 achieves state-of-the-art results. This connects directly to Anthropic’s claim that Opus 5 is their most aligned model with the lowest measured deceptive behavior.

Pricing Breakdown

Opus 5 maintains the same pricing as its predecessor, making it a free upgrade for existing Opus 4.8 users:

Mode	Input	Output
Standard	$5/M tokens	$25/M tokens
Fast	$10/M tokens	$50/M tokens

For context, here is how this compares to alternatives:

Sonnet 5: $2/$10 (introductory), then $3/$15
Fable 5: $10/$50
GPT-5.6 Sol: $6/$18

See our full AI API pricing comparison for a detailed breakdown across all major providers.

Fast Mode

Fast mode doubles the per-token cost but delivers 2.5x the speed. This is ideal for interactive coding sessions where latency matters more than cost. At $10/$50, fast mode matches Fable 5’s base pricing but delivers responses significantly faster.

Effort Levels: 5-Level Thinking Control

One of Opus 5’s most significant features is its 5-level effort control system. Thinking is on by default, but you can adjust how much compute the model uses:

min - Minimal thinking. Quick responses for simple tasks like formatting or basic questions. Lowest cost per request.
low - Light reasoning. Suitable for straightforward coding tasks, summaries, and translations.
medium - Balanced thinking. Good default for most professional tasks. Moderate cost and latency.
high - Deep reasoning. Complex problem-solving, multi-step planning, and thorough code review.
max - Maximum compute. Research-level problems, novel algorithm design, and tasks where accuracy is critical regardless of cost.

The effort level directly affects token usage (and therefore cost), so choosing the right level for each task optimizes your spend without sacrificing quality where it matters.

API Setup

Getting started with Opus 5 through the Anthropic API is straightforward:

import anthropic

client = anthropic.Anthropic()

message = client.messages.create(
    model="claude-opus-5",
    max_tokens=8192,
    thinking={
        "type": "enabled",
        "budget_tokens": 4096,
        "effort": "high"
    },
    messages=[
        {"role": "user", "content": "Your prompt here"}
    ]
)

Key parameters to note:

Set model to claude-opus-5
Thinking is enabled by default; you control it via the effort field
budget_tokens caps how many tokens the model can use for internal reasoning
The 128K max output allows for very long generated responses

For routing through multiple providers, check our OpenRouter guide which covers how to access Opus 5 alongside other models through a unified API.

How Opus 5 Compares to Fable 5

The Opus 5 vs Fable 5 decision is the most common question developers face. Here is the quick summary:

Choose Opus 5 when:

Cost efficiency matters (half the price of Fable 5)
You are doing software development (within 0.5% on CursorBench)
You need general reasoning (43.3% vs 33.7% on Frontier-Bench)
You want fewer safety interventions (85% fewer than Fable 5)

Choose Fable 5 when:

You work in cybersecurity (Mythos 5 tier safeguards)
You need the absolute hardest reasoning tasks solved
Cost is not a constraint

For most developers, Opus 5 is the better choice. It delivers nearly identical coding performance at half the cost with significantly fewer restrictive interventions.

How Opus 5 Compares to Opus 4.8

This is simpler: always upgrade. Opus 5 costs the same as Opus 4.8 but doubles Frontier-Bench performance, adds thinking by default, and improves on every measured benchmark. There is no reason to stay on Opus 4.8 unless you have a specific reproducibility requirement. Read our Opus 4.8 guide for the full migration context.

Use Cases

Software Development

Opus 5 excels at complex, multi-step coding tasks. It verifies its own work and iterates until reaching a correct solution. Combined with Claude Code, it handles:

Large refactoring across multiple files
Architecture design and implementation
Bug diagnosis in unfamiliar codebases
Test generation and validation

Research and Analysis

The 1M context window allows ingesting entire research papers, datasets, or documentation sets. At max effort, Opus 5 produces research-grade analysis with proper reasoning chains.

Daily Professional Work

Anthropic designed Opus 5 for daily use. It is the default model on Claude Max and the strongest available on Claude Pro. For writing, planning, data analysis, and general knowledge work, the medium effort level provides excellent results at reasonable cost.

Agentic Workflows

OSWorld 2.0 results demonstrate that Opus 5 is the best model for autonomous agent tasks. It navigates complex environments, uses tools effectively, and recovers from errors without human intervention.

Alignment and Safety

Opus 5 is Anthropic’s most aligned model. It shows the lowest measured deceptive behavior across their evaluation suite. Importantly, it achieves this while being less restrictive than Fable 5, with 85% fewer safety interventions. This means fewer false positives where the model refuses legitimate requests.

There are no data retention requirements for API usage, giving teams full control over their data handling.

Availability

Opus 5 is available through:

Anthropic API (direct access)
Claude Pro and Claude Max (consumer products)
Third-party providers like OpenRouter
Claude Code for development workflows

Unlike GPT-5.6 Sol which requires government-gated access, Opus 5 is generally available to all developers and organizations.

FAQ

Is Claude Opus 5 worth the upgrade from Opus 4.8?

Yes, unconditionally. Opus 5 costs the same as Opus 4.8 ($5/$25 per million tokens) while doubling Frontier-Bench performance and adding thinking by default. It is a free upgrade with no downsides.

How does Opus 5 compare to Fable 5 for coding?

Opus 5 scores within 0.5% of Fable 5 on CursorBench 3.2 while costing half as much. For the vast majority of coding tasks, Opus 5 is the better value. Fable 5 only justifies its premium for specialized cybersecurity work.

What effort level should I use for coding?

Start with “high” for complex multi-step tasks and “medium” for everyday coding. Use “max” only for novel algorithm design or research-level problems. “Low” works well for simple formatting or boilerplate generation.

Can I use Opus 5 with Claude Code?

Yes. Opus 5 works with Claude Code and is the recommended model for complex development tasks. See our Claude Code setup guide for configuration details.

Does Opus 5 have data retention requirements?

No. Unlike some competing models, Opus 5 has no data retention requirements for API usage. Your data remains under your control.

What is the difference between standard and fast mode?

Fast mode costs twice as much ($10/$50 vs $5/$25) but delivers responses at 2.5x the speed. Use it for interactive sessions where latency impacts your workflow. Use standard mode for batch processing or background tasks where speed is less critical.