Claude Opus 4.6

Claims and evidence

• Released 5 February 2026 ● Primary source[1] [2]Availability: Released

• Status Available ● Primary source[2]Availability [3]Model status table

• Successor of Claude Opus 4.5 ● Primary source[1]opening section

• Change · Context length Anthropic says it is the first Opus-class model with a 1M token context window, offered in beta at launch and out of beta from 13 March 2026.Compared with Claude Opus 4.5 ● Primary source[1] [4]February 5, 2026; March 13, 2026
• Change · Reasoning Adds adaptive thinking, in which the model decides how much to think, steered by the effort setting; manual thinking budgets are deprecated.Compared with Claude Opus 4.5 ● Primary source[4]February 5, 2026 [1]
• Change · Other Adds context compaction in beta on the API, which summarises older context during long-running tasks.Compared with Claude Opus 4.5 ● Primary source[1] [4]February 5, 2026
• Change · Other Prefilling the assistant message is no longer supported.Compared with Claude Opus 4.5 ● Primary source[4]February 5, 2026

• Input text, image ● Primary source[2]Capabilities: Input and output
• Output text ● Primary source[2]Capabilities: Input and output
• Context window 1M tokensThe launch announcement offered the 1M token context window in beta; the model page lists 1M tokens. ● Primary source[2]Capabilities: Context window
• Parameters Not disclosedNot disclosed by Anthropic. No claim madeNo source
• Access API, consumer app, cloud partner ● Primary source[1]opening section

Lineage

Variants

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Related AI Radar coverage

• Eval awareness in Claude Opus 4.6’s BrowseComp performanceAnthropic · Engineering · 6 March 2026
• Introducing Claude Opus 4.6Anthropic · YouTube · 5 February 2026
• Building a C compiler with a team of parallel ClaudesAnthropic · Engineering · 5 February 2026

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