Drafted with AI tools and edited by a human. The figures and conclusions were checked by a GPUniq editor.
TL;DR
Claude Sonnet 5.5 costs $2 per million input tokens and $10 per million output tokens, delivers more than 30% faster inference, and scores 70.6% on Terminal-Bench 4.0 agentic coding versus Sonnet 5's 10.3%. For everyday coding, document work, and customer support, it's a cost-neutral upgrade with measurable gains.
Why Sonnet 5.5 matters
Anthropic released Sonnet 5.5 on September 28, 2026, positioned as the productivity tier for well-scoped everyday tasks: coding, content creation, document polish. The headline is simple. You get a faster, more capable model at $2 per million input tokens and $10 per million output tokens.
Price parity removes the usual migration calculus. There's no "is the improvement worth the extra cost" question. The 1M token context window is a substantial capacity, so nothing breaks if you're already sending large payloads.
Speed matters most in real-time workflows. Chatbots, streaming code completions, and high-volume batch jobs all benefit from faster inference without any change to your budget or prompt structure.
How much faster is Sonnet 5.5?
Anthropic states Sonnet 5.5 is more than 30% faster than Sonnet 5 in inference speed.
For a chatbot handling 10,000 requests per hour, a 30% latency reduction means you can serve more users on the same infrastructure or cut response times noticeably. For streaming code completions in an IDE, the difference is felt immediately.
The speed gain doesn't trade off against output quality. The model supports high-effort reasoning and "thinking" mode, including the between_tools setting for agentic workflows.
Does Sonnet 5.5 beat Sonnet 5 on coding?
Yes, by a large margin on both benchmarks.
| Benchmark | Sonnet 5.5 | Sonnet 5 | Gain |
|---|---|---|---|
| Terminal-Bench 4.0 (agentic coding) | 70.6% | 10.3% | +60.3 pp |
| CursorBench 4.0 (main) | 55.5% | 34.1% | +21.4 pp |
The Terminal-Bench gap is striking. Sonnet 5 at 10.3% versus Sonnet 5.5 at 70.6% isn't a marginal improvement. It's a different class of capability for autonomous terminal-based coding tasks. CursorBench 4.0 reflects real IDE integration, which is where most developers actually interact with the model. And these numbers explain why Sonnet 5.5 is a strong choice there.
Should you migrate all calls?
For most teams: yes, default to Sonnet 5.5. The cost is identical, the speed is better, and the coding benchmarks are dramatically higher.
Workloads that fit well:
- Code completion and review in Cursor or VS Code
- Batch document processing and content analysis
- Customer support automation
- Any workflow currently running on Sonnet 5
Where to pause: complex, open-ended reasoning tasks. Anthropic explicitly notes that Opus 5.5 remains the stronger choice for very complex, open-ended tasks and that max quality on the hardest tasks still lags the best Opus performance. If you're routing research-heavy or novel problem-solving tasks to Sonnet 5 today, those should go to Opus 5.5, not Sonnet 5.5.
A sensible default: Sonnet 5.5 for everything, with explicit routing to Opus 5.5 for tasks you've confirmed require deep multi-step reasoning.
When does Opus 5.5 still win?
Open-ended reasoning, novel problem-solving, complex multi-domain analysis. Anthropic's own limitations documentation for Sonnet 5.5 is direct about this.
The cost difference is real. Opus 5.5 pricing is not published here, so no comparison figure is available. What is clear is that Sonnet 5.5 runs at $2 input and $10 output per million tokens. Use it as your default and route to Opus 5.5 only when you've confirmed the task genuinely requires it. Most coding, document, and support workloads don't.
Higher effort levels in Sonnet 5.5 also consume significantly more tokens, which increases cost even at Sonnet pricing. Worth keeping in mind for workflows that use extended thinking modes.
Context window and output limits
Sonnet 5.5 supports a 1,000,000 token context window with a 128,000 token maximum output.
In practice, 1M tokens means you can send an entire codebase, a full legal document, or a multi-file project in a single API call. No chunking, no session management, no stitching responses back together. For document-heavy workflows, this eliminates a whole class of engineering complexity.
The 128,000 max output is substantial for code generation. A large module, a full test suite, or a long-form analysis in one shot is possible without hitting output limits.
Pricing at a glance
| Model | Input, $/M tokens | Output, $/M tokens | Cache reads, $/M tokens |
|---|---|---|---|
| Sonnet 5.5 | $2.00 | $10.00 | $0.20 |
| Sonnet 5 | - | - | - |
Cache reads for Sonnet 5.5 are $0.20 per million tokens, which makes repeated-context workflows cheaper at scale. I'd factor that in early if you're building anything with a shared system prompt or large static context.
What use cases fit best?
Sonnet 5.5 is built for well-scoped tasks where speed and coding capability matter. According to Anthropic's summary, it's optimized for coding, content creation, and document polish.
Good fits:
- IDE code completion (Cursor, VS Code plugins). CursorBench 4.0 at 55.5% backs this up.
- Terminal-based agentic coding. Terminal-Bench 4.0 at 70.6% is the clearest signal.
- Batch document processing where you need 1M context without chunking.
- Customer support automation with low latency requirements.
- Content generation and document polish at scale.
Poor fits, per Anthropic's own limitations:
- Open-ended research requiring novel reasoning.
- Complex multi-step analysis where Opus 5.5's depth is needed.
- Tasks where you've already found Sonnet-tier models insufficient.
The model is available via Anthropic's API, AWS, Microsoft Azure, and Google Cloud under the model ID claude-sonnet-5-5. It handles text, images, and PDFs, so multimodal document workflows are covered without switching models.
Related on the GPUniq blog
Methodology
Facts are compiled from the vendor's own announcement and documentation, linked below, at the time of writing; where the vendor hasn't published a number it is marked as such. GPUniq prices, when the model is already available here, come from our live catalog.
Sources
- 1.Introducing Claude Sonnet 5.5 — Anthropic (accessed )
- 2.Claude Sonnet 5.5 | Cursor Docs — Cursor / Anthropic (accessed )
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