As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/m/claude-opus-4-5/

# Claude Opus 4.5

Anthropic, Claude 4 family. Status: legacy. Type: reasoning model. Released: 2025-11-24. Training cutoff: 2025-05.

## How to call it

| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| Anthropic API (Claude API) | `claude-opus-4-5-20251101` (alias `claude-opus-4-5`) | https://api.anthropic.com/v1/messages | https://platform.claude.com/docs/en/models/opus-4-5/overview |
| AWS Bedrock (InvokeModel) | `anthropic.claude-opus-4-5-20251101-v1:0` |  | https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy |
| Google Cloud Vertex AI | `claude-opus-4-5@20251101` |  | https://platform.claude.com/docs/en/build-with-claude/claude-on-vertex-ai |
| Microsoft Foundry (Azure) | `claude-opus-4-5` |  | https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry |
| Claude Platform on AWS | `claude-opus-4-5` |  | https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws |
| OpenRouter | `anthropic/claude-opus-4.5` |  | https://openrouter.ai/anthropic/claude-opus-4.5 |
| Web app |  |  | https://claude.ai |

## Pricing

- Input: $5 per 1M tokens
- Output: $25 per 1M tokens
- Cache read: $0.50 per 1M tokens
- Unit as published: per 1M tokens (USD); Batch API 50% off
- Source: https://platform.claude.com/docs/en/about-claude/pricing
- Last checked: 2026-09-29

## Specs

- Input: text, image, pdf
- Output: text
- Context window: 200,000 tokens
- Max output: 64,000 tokens
- Open weights: no
- Licence: proprietary

## What it has not seen

- Published training cutoff: 2025-05 (May 2025).
- AI events after it on Post-Cutoff: 2,019 (467 major, 89 historic), as of 2026-11-13.
- Already missing at launch: 45.
- Briefings of the news since May 2025: https://postcutoff.com/briefings/cutoff-2025-05-s.md (short), https://postcutoff.com/briefings/cutoff-2025-05-m.md (medium), https://postcutoff.com/briefings/cutoff-2025-05.md (full).
- Its card, with five things it has never heard of: https://postcutoff.com/you/claude-opus-4-5/
- Claude Opus 4.5 is named in one of our documented cases of cutoff blindness (case 006). https://postcutoff.com/why/006-claude-sonnet-4-says-it-is-claude-3-5-sonnet/

## What stands out

- Beat all human candidates on Anthropic's engineering exam (first): Scored higher than any human candidate on Anthropic's take-home engineering exam within the 2-hour limit. Source: https://www.anthropic.com/news/claude-opus-4-5
- Effort parameter (first): First model with the effort parameter. At medium effort it matched Sonnet 4.5's best score with 76% fewer output tokens. Source: https://www.anthropic.com/news/claude-opus-4-5
- Prompt-injection robustness: Anthropic claimed it was harder to trick with prompt injection than any other frontier model at the time. Source: https://www.anthropic.com/news/claude-opus-4-5
- Opus price cut: Opus-class pricing dropped to $5/$25 per MTok, from $15/$75. Source: https://www.anthropic.com/news/claude-opus-4-5

## Notes

Snapshot claude-opus-4-5-20251101 (alias claude-opus-4-5). Extended thinking (budget_tokens); effort low/medium/high. Training data cutoff Aug 2025. Retirement not sooner than 2026-11-24.

Legacy Opus; migrate to `claude-opus-5-5`.

```bash
curl https://api.anthropic.com/v1/messages \
 -H "x-api-key: $ANTHROPIC_API_KEY" -H "anthropic-version: 2023-06-01" -H "content-type: application/json" \
 -d '{"model":"claude-opus-4-5","max_tokens":16000,"messages":[{"role":"user","content":"Hello"}]}'
```

Sources:
- Model page: https://platform.claude.com/docs/en/models/opus-4-5/overview
- Announcement: https://www.anthropic.com/news/claude-opus-4-5
- Pricing: https://platform.claude.com/docs/en/about-claude/pricing
- Models overview: https://platform.claude.com/docs/en/about-claude/models/overview
- Deprecations: https://platform.claude.com/docs/en/about-claude/model-deprecations

Model page: https://postcutoff.com/m/claude-opus-4-5/