I'm Hamamoto from TIMEWELL Inc.
In November 2025, Anthropic released Claude Opus 4.5, completing the Claude 4.5 family.
Sonnet 4.5 is called "the world's most powerful coding model," while Opus 4.5 achieves "high accuracy on long-duration tasks with 65% fewer tokens" — the Claude 4.5 series has won overwhelming support from both developers and business professionals.
This article explains all Claude 4.5 family models, benchmark results, pricing, and the latest Claude Code features.
Claude 4.5: 2026 Overview
| Item | Details |
|---|---|
| Sonnet 4.5 Release | September 29, 2025 |
| Haiku 4.5 Release | October 2025 |
| Opus 4.5 Release | November 24, 2025 |
| SWE-bench | Sonnet 4.5 achieves top score |
| OSWorld | Sonnet 4.5 tops at 61.4% |
| Claude Code Cowork | Released January 2026 |
The Claude 4.5 Family Structure
Three-Model Lineup
The Claude 4.5 family consists of three models suited to different use cases.
| Model | Characteristics | Primary Use Cases | Pricing (Input/Output) |
|---|---|---|---|
| Opus 4.5 | Highest performance, long-duration tasks | Complex development, research | $5/$25 per 1M tokens |
| Sonnet 4.5 | Best-in-class coding | Development, agents | $3/$15 per 1M tokens |
| Haiku 4.5 | Fast, low-cost | Everyday tasks, chat | $0.25/$1.25 per 1M tokens |
Release Timeline
Claude release history for 2025:
| Date | Release |
|---|---|
| May 22, 2025 | Claude Sonnet 4, Opus 4 |
| August 5, 2025 | Claude Opus 4.1 |
| September 29, 2025 | Claude Sonnet 4.5 |
| October 2025 | Claude Haiku 4.5 |
| November 24, 2025 | Claude Opus 4.5 |
Claude Sonnet 4.5 — The World's Most Powerful Coding Model
Benchmark Results
Anthropic positions Sonnet 4.5 as "the world's most powerful coding model," "the best model for building agents," and "the best model for computer use."
SWE-bench Verified: Sonnet 4.5 achieves the top score on SWE-bench Verified, demonstrating superior performance over other models on real-world software engineering tasks.
OSWorld (Computer Use Benchmark):
| Model | Score |
|---|---|
| Sonnet 4 (May 2025) | 42.2% |
| Sonnet 4.5 (September 2025) | 61.4% |
A 19.2-point improvement in just four months demonstrates a remarkable pace of evolution.
Sustained Focus for 30+ Hours
Sonnet 4.5 has been observed to maintain focus on complex multi-step tasks for over 30 hours.
Use cases:
- Large-scale refactoring
- Feature implementation spanning multiple files
- Long-duration code reviews
- Agentic development tasks
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Claude Opus 4.5 — The King of Long-Duration Tasks
A Revolution in Efficiency
Released on November 24, 2025, Opus 4.5 achieves groundbreaking efficiency on long-duration coding tasks.
Performance characteristics:
- 65% reduction in token usage alongside improved test pass rates
- Computation control via the "effort" parameter
- 200,000-token context window
- 64,000-token output limit
The Effort Parameter
One of Opus 4.5's innovative features is the introduction of the "effort" parameter (low/medium/high).
| Effort Setting | Characteristics |
|---|---|
| low | Fast, low-cost, for simple tasks |
| medium | Equivalent to Sonnet 4.5 scores, 76% fewer tokens |
| high | Maximum accuracy, for complex tasks |
With the medium setting, you can maintain Sonnet 4.5's SWE-bench score while reducing output tokens by 76%. This enables high-quality output while optimizing for cost efficiency.
Safety Level
Opus 4.5 is classified as "Level 3" on Anthropic's four-tier safety scale — meaning it is powerful enough to carry "significantly elevated risk."
Claude Code 2.0 — New Features for Developers
Major Updates
Claude Code received a major update in conjunction with the Claude 4.5 family release.
New features:
Checkpoint Function
- Save progress and roll back to a previous state
- The most-requested feature
Sub-Agent Capability
- Spawn specialized AI assistants that operate in parallel
- Each sub-agent has its own context window and toolset
- Specialize in frontend, backend, testing, and more
VS Code Extension
- Native VS Code extension released
- Deep integration with the IDE
Cowork (GUI Version)
- Released January 2026
- Graphical user interface for non-technical users
- Available as a web version and iOS app
Files API
A new Files API is available for developers.
Files API characteristics:
- File upload and management
- Integration with Model Context Protocol (MCP)
- Code execution tool integration
Then vs. Now: Claude's Evolution
| Item | Then (Claude 3.5 Sonnet, June 2024) | Now (Claude 4.5, January 2026) |
|---|---|---|
| Latest Model | Claude 3.5 Sonnet | Claude Opus 4.5 |
| SWE-bench | High score | Top score |
| OSWorld | Not measured | 61.4% (top) |
| Long-Duration Tasks | Limited | 30+ hours sustained |
| Effort Parameter | None | Yes (low/medium/high) |
| Claude Code | Early version | Checkpoints, sub-agents |
| GUI Version | None | Cowork (January 2026) |
Pricing
API Pricing
| Model | Input | Output |
|---|---|---|
| Opus 4.5 | $5 / 1M tokens | $25 / 1M tokens |
| Sonnet 4.5 | $3 / 1M tokens | $15 / 1M tokens |
| Haiku 4.5 | $0.25 / 1M tokens | $1.25 / 1M tokens |
claude.ai Plans
| Plan | Monthly Price | Features |
|---|---|---|
| Free | Free | Sonnet 4.5 (limited) |
| Pro | $20 | Opus 4.5 access, priority use |
| Team | Custom | Team management features |
| Enterprise | Custom | Enterprise-grade security |
Practical Use Cases
1. Software Development
Development support leveraging Sonnet 4.5's coding capabilities.
Use cases:
- New feature implementation
- Bug identification and fixes
- Code reviews
- Test automation
2. Long-Duration Projects
Leveraging Opus 4.5's ability to sustain long-duration tasks.
Use cases:
- Large-scale refactoring
- System migrations
- Complex architecture design
- Documentation work
3. Agent Development
Autonomous development using Claude Code's sub-agent capabilities.
Use cases:
- Parallel frontend/backend development
- CI/CD pipeline automation
- Test-driven development in practice
Competitive Comparisons
vs. GPT-5.2
| Item | Claude Opus 4.5 | GPT-5.2 Pro |
|---|---|---|
| Coding | SWE-bench best | High performance |
| Context | 200K | 400K |
| Output Tokens | 64K | 128K |
| Long-Duration Tasks | 30+ hours | — |
| Effort Parameter | Yes | No |
| Pricing (Input) | $5/1M | $30/1M |
Claude excels in coding and long-duration tasks; GPT-5.2 has an edge in large-context and output volume.
vs. Google Gemini 3
| Item | Claude Opus 4.5 | Gemini 3 Ultra |
|---|---|---|
| Coding | Best-in-class | High performance |
| Multimodal | Limited | Best-in-class |
| Context | 200K | 1M+ |
| Agents | Powerful | Developing |
Using the right model for the right task is recommended.
Enterprise Adoption Strategy
Companies That Should Adopt
- Companies that do frequent software development
- Companies with long-term code improvement projects
- Companies aiming for automation via AI agents
- Companies seeking cost-effective AI utilization
Adoption Approach
Phase 1: Evaluation
- Trial with claude.ai Pro plan ($20/month)
- Measure effectiveness across primary use cases
Phase 2: Pilot
- Introduce Claude Code
- Proof of concept with the development team
Phase 3: Full Deployment
- Integrate into business systems via API
- Migrate to Team/Enterprise plan
Summary
The Claude 4.5 family represents the latest suite of AI models, completed in the second half of 2025.
Key takeaways:
- The Claude 4.5 family consists of three models: Opus, Sonnet, and Haiku
- Sonnet 4.5 is "the world's most powerful coding model" with the top SWE-bench score
- Opus 4.5 achieves high accuracy on long-duration tasks with 65% fewer tokens
- The effort parameter (low/medium/high) controls computational load
- Claude Code gains checkpoint and sub-agent capabilities
- Cowork (GUI version) released January 2026
Claude 4.5 delivers performance that outstrips other AI models, particularly in coding and long-duration tasks. For businesses centered on software development, adopting Claude 4.5 is highly likely to translate into competitive advantage.
For enterprises, how effectively Claude 4.5 is utilized will be an important factor determining development efficiency and quality in 2026.
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