$ diff claude-opus-5-5 deepseek-v4-1-flash
Claude Opus 5.5 vs DeepSeek V4.1-Flash
Values come from Claude Opus 5.5 and DeepSeek V4.1-Flash, where each is cited to its source. This page states no benchmark result and ranks neither model — it puts two published specifications next to each other. Where a lab has not published a figure, the row says so rather than guessing.
AnthropicClaude Opus 5.5
- context
- 1M
- weights
- closed
- $/M in
- $4
- $/M out
- $20
- context
- 1M
- weights
- open
- $/M in
- $0.15
- $/M out
- $0.6
What actually differs
- Context window
- Identical — both accept 1M tokens, so context length is not a reason to pick either.
- Input price
- DeepSeek V4.1-Flash at $0.15/M against $4/M — 26.7× cheaper to feed. Standard rates: one of these labs also quotes a lower cached-input tier, which applies only when a prefix is reused — see the full spec below.
- Output price
- DeepSeek V4.1-Flash at $0.6/M against $20/M — 33.3× cheaper to generate. Output dominates the bill on most agentic workloads, where the model writes far more than it reads.
- Weights
- DeepSeek V4.1-Flash publishes weights (MIT (open-weight)); Claude Opus 5.5 is API-only. That decides self-hosting, air-gapped deployment and fine-tuning before any capability question does.
- Recency
- Claude Opus 5.5 shipped 12 days after DeepSeek V4.1-Flash (2026-09-22 vs 2026-09-10).
Full spec
| Attribute | Claude Opus 5.5 | DeepSeek V4.1-Flash |
|---|---|---|
| Developer | Anthropic | DeepSeek |
| Released | 2026-09-22 | 2026-09-10 |
| Context window | 1M tokens | 1,000,000 |
| Pricing | $4/M input · $20/M output · cache reads $0.20/M · cache writes $5/M | $0.15/M input (cache miss) · $0.003/M input (cache hit) · $0.60/M output, off-peak; peak rates double — see Pricing |
| License | proprietary (API-only; no weight release) | MIT (open-weight) |
| Availability | Claude apps, Claude Code, Claude API as `claude-opus-5-5`, Amazon Bedrock, Google Cloud Vertex AI, Microsoft Foundry | DeepSeek API, Hugging Face (`deepseek-ai/DeepSeek-V4.1-Flash`) |