Claude Sonnet 5.5: Opus-Level Work at Half the Price

By ChatGBot · October 5, 2026

Anthropic has released Claude Sonnet 5.5, the mid-tier sibling to Opus 5.5, and it is the value story of the Claude 5.5 family. It nearly matches the flagship on most work, runs faster, and costs half as much. For many people it is the new default. Here is what changed and when to use it.

Near-Opus performance, half the cost

Sonnet 5.5 is priced at $2 per million input tokens and $10 per million output tokens, exactly half of Claude Opus 5.5 at $4 / $20, and unchanged from Sonnet 5. Anthropic says it nearly matches Opus 5.5 on most knowledge-work benchmarks, so you get flagship-class quality for routine work without paying flagship prices.

It actually beats Opus 5.5 at coding

On the Terminal-Bench 4.0 coding benchmark, Sonnet 5.5 scored 70.6% against Opus 5.5's 66.4%. It also runs more than 30% faster and costs up to 30% less per task. For a lot of day-to-day coding and agent work, the cheaper model is now the better pick. See our Claude for coding guide.

Big context, built for long work

Sonnet 5.5 keeps a 1 million token context window with up to 128K tokens of output, so it can hold large codebases or long documents in a single session. For how the lineup fits together, see Claude models explained.

Sonnet 5.5 vs Opus 5.5: which should you use?

• Use Sonnet 5.5 for everyday coding, writing, analysis and agents — it is faster, cheaper, and close to the top on quality.
• Use Opus 5.5 for the hardest reasoning tasks where you want the absolute best, cost aside.
• The simplest approach: keep both on hand and switch per task instead of committing to one.

Where it fits

Sonnet 5.5 caps a remarkable few weeks: Opus 5.5, GPT-6 Sol and Luna, GPT-6.1 Sol, Grok 4.7 and Gemini 4 Argon all shipped around the same time. The frontier is getting cheaper fast, and the real win is matching the right model to each job. For the full picture, read our September 2026 AI model releases roundup.

Frequently asked questions

When was Claude Sonnet 5.5 released? September 28, 2026, as the mid-tier model in the Claude 5.5 family alongside Opus 5.5.

How much does Claude Sonnet 5.5 cost? $2 per million input tokens and $10 per million output tokens, half the price of Opus 5.5.

Is Sonnet 5.5 better than Opus 5.5? It beats Opus 5.5 on the Terminal-Bench 4.0 coding benchmark and nearly matches it on knowledge work, while being faster and cheaper. Opus 5.5 still leads on the very hardest tasks.

Can I use Claude Sonnet in ChatGBot? Yes. ChatGBot gives you Claude along with GPT, DeepSeek, Qwen and GLM under one subscription, so you can switch models mid chat.