Claude Code Now Starts on Opus 5.5 for $20 Pro Users. Here's What That Does to Your Limits.

Anthropic's Opus 5.5 launch post focused on benchmarks and price. The change most Claude Code users will actually notice came in a one-line changelog entry: if you're on the $20 Pro plan or a Team Standard seat and never picked a model, your sessions now open on Opus instead of Sonnet.

What changed in Claude Code

• Default model: Claude Code 2.1.280 "changed the default model on Pro and Team Standard plans from Sonnet to Opus, matching Max, Team Premium, and Enterprise."
• Default Opus: the same release added Claude Opus 5.5 as "now the default Opus model," with a 1M-token context window.
• Effort settings: an effort level saved before /effort became per-model no longer carries over to new models such as Opus 5.5, which start at their own default until you choose a level.

Opus 5.5 by the numbers

Anthropic says Opus 5.5 costs about 40% less than Opus 5 on typical workloads, because it is cheaper per token and uses fewer tokens per task, and that it generates output more than 30% faster. On its own benchmark table, Opus 5.5 scores 66.4% on Terminal-Bench 4.0 against 57.9% for GPT-6 Astra (as reported by OpenAI) and 55.8% for Claude Fable 5.1, and 57.8% on CursorBench 4.0. Anthropic cautions that at this level, benchmark margins are "a less reliable guide to real-world differences."

What it means for your usage limits

On a subscription, the switch doesn't add to your bill, but it does change how fast you use your allowance. Anthropic says it is raising five-hour usage limits on Pro, Max, Team, and seat-based Enterprise plans and giving subscribers a saved rate-limit reset, though it hasn't published figures. Opus 5.5 also can't run with thinking switched off, and thinking tokens count as output. As MIXED points out, Anthropic's own cost guidance still says Sonnet handles most coding tasks well and costs less, and subagents that inherit the session model will also run on Opus.

• To go back to Sonnet for a session: run /model.
• To change the default: set it in /config.
• API and cloud-provider accounts billed per token are not affected by the default change, which applies to subscription plans.

What's next

Anthropic says Claude Sonnet 5.5 and Claude Haiku 5.5 will follow "in the coming weeks" with many of the same improvements. Opus 5.5 is available across Anthropic's platform, AWS, Google Cloud, and Microsoft Azure. For cybersecurity tasks, it ships with safeguards similar to Fable 5.1's, which re-route most cybersecurity tasks to Opus 4.8; Anthropic says it will soon expand its Cyber Verification Program to include Opus 5.5.

What this means if you're choosing an AI coding tool

For $20 a month, Claude Code Pro users now get Anthropic's newest top model by default, which makes the entry plan considerably stronger than it was a week ago. The trade-off is allowance: long agentic runs on Opus will reach the five-hour cap sooner than the same work on Sonnet. If you mostly do routine edits, setting Sonnet as your default and switching to Opus for hard problems is the cheaper pattern until Sonnet 5.5 ships.