Anthropic hasn’t announced a specific “Claude 4” as a distinct release — the current model generation is the Claude 4.x series, with Claude Opus 4.6 and Claude Sonnet 4.6 as the current flagship models. If you’re searching for Claude 4, you’re likely looking for the current generation. Here’s exactly what’s live, what the naming means, and what to watch for next.
claude-opus-4-6) and Claude Sonnet 4.6 (claude-sonnet-4-6) are Anthropic’s current production models. These are the “Claude 4” generation.
The Current Claude 4.x Lineup
| Model | API String | Status | Position |
|---|---|---|---|
| Claude Opus 4.6 | claude-opus-4-6 | ✅ Live | Flagship / maximum capability |
| Claude Sonnet 4.6 | claude-sonnet-4-6 | ✅ Live | Production default / balanced |
| Claude Haiku 4.5 | claude-haiku-4-5-20251001 | ✅ Live | Speed / cost efficiency |
Claude Model Naming: How It Works
Anthropic uses a generation.version naming convention. The “4” in Claude 4.6 denotes the fourth major model generation. The “.6” is a version within that generation — a meaningful update that improves on the generation’s base capabilities without being an entirely new architecture.
This is why there’s no single “Claude 4 release date” to point to — the Claude 4.x family has been rolling out incrementally, with different model tiers (Haiku, Sonnet, Opus) shipping at different points within the generation. The generation is live; you’re using it now if you’re on current Claude models.
Claude 4 vs Claude 3: What Changed
The jump from Claude 3.x to Claude 4.x brought improvements across reasoning, coding accuracy, instruction-following, and agentic capability. Claude 3.5 Sonnet — released in mid-2024 — was the model that first clearly demonstrated Claude could compete with and often exceed GPT-4o on most professional benchmarks. The 4.x series extended those gains.
The most notable improvements in the 4.x generation: stronger performance on multi-step reasoning, better coherence in long agentic sessions, and improved accuracy on coding tasks including the SWE-bench benchmark for real-world software engineering.
What Comes After Claude 4.x
Anthropic hasn’t announced a Claude 5 release date or feature set. Based on the pace of releases — major generations arriving every several months, point releases more frequently — the next major generation will likely arrive within the year. When it does, the pattern will hold: the new mid-tier model (Sonnet) will likely outperform the current top-tier (Opus) on most tasks, at a fraction of the cost.
For anticipation content on the next Sonnet release, see Claude Sonnet 5: What We Know. For the current model API strings and specs, see Claude API Model Strings — Complete Reference.
Frequently Asked Questions
When does Claude 4 come out?
Claude 4 is already out — the current model generation is Claude 4.x. Claude Opus 4.6 and Claude Sonnet 4.6 are live and in production as of April 2026. There’s no separate “Claude 4” launch pending; you’re on it.
What is Claude 4?
Claude 4 refers to Anthropic’s fourth major model generation — currently the Claude 4.x series including Opus 4.6, Sonnet 4.6, and Haiku 4.5. The generation brought improvements in reasoning, coding, instruction-following, and agentic performance over Claude 3.
Is Claude 4 better than Claude 3?
Yes, across most benchmarks and practical tasks. The Claude 4.x generation improves on Claude 3 in reasoning accuracy, coding performance, long-context coherence, and agentic capability. Claude 3.5 Sonnet — the bridge between generations — was the model that first demonstrated Claude could consistently outperform GPT-4o on professional tasks.
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