High-volume, cost-sensitive work
Choose Claude Opus 5.5
Claude Opus 5.5 costs 20% less on a typical mix of three input tokens for every output token ($8.00 against $10.00 per million tokens).
Claude Opus 4.5 vs Claude Opus 5.5: price, context and capabilities
Choose Claude Opus 5.5 for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), very long inputs, reasoning over long documents and the latest release; on the other points the two are level or the data is missing.
In short
- Claude Opus 5.5 is 20% cheaper than Claude Opus 4.5 at the headline price ($8.00 / 1M tokens vs $10.00 / 1M tokens).
- Claude Opus 5.5 reads more per request: 1M tokens against 200k.
- Claude Opus 5.5 is the newer model (September 2026, against November 2025).
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose Claude Opus 5.5
Claude Opus 5.5 charges $20.00 per million output tokens, against $25.00 for Claude Opus 4.5. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose Claude Opus 5.5
Claude Opus 5.5 charges $0.20 per million cached input tokens, against $0.50 for Claude Opus 4.5.
Very long inputs
Choose Claude Opus 5.5
Claude Opus 5.5 reads up to 1M tokens per request, against 200k for Claude Opus 4.5.
Reasoning over long documents
Choose Claude Opus 5.5
Claude Opus 5.5 scores 84.7% on Long-context reasoning (AA-LCR), against 70.7% for Claude Opus 4.5.
Latest release
Choose Claude Opus 5.5
Claude Opus 5.5 is the newer release (September 2026, against November 2025 for Claude Opus 4.5).
Monthly cost at three volumes
| Volume | Claude Opus 4.5 | Claude Opus 5.5 | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $11.25 | $9.00 | Claude Opus 5.5, $2.25 less |
| Production: 20M input, 5M output tokens | $225.00 | $180.00 | Claude Opus 5.5, $45.00 less |
| Scale: 500M input, 100M output tokens | $5,000 | $4,000 | Claude Opus 5.5, $1,000 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Opus 4.5 | Claude Opus 5.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Category | Language models | Language models |
| Status | Legacy | Generally available |
| Headline price | $10.00 / 1M tokens | $8.00 / 1M tokens |
| Input | $5.00 / 1M tokens | $4.00 / 1M tokens |
| Output | $25.00 / 1M tokens | $20.00 / 1M tokens |
| Cached input | $0.50 / 1M tokens | $0.20 / 1M tokens |
| Context window | 200k | 1M |
| Max output | 64k | 128k |
| Released | November 2025 | September 2026 |
| Knowledge cutoff | No data | June 2026 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | claude-opus-4-5-20251101 | claude-opus-5-5 |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Opus 4.5 | Claude Opus 5.5 |
|---|---|---|
| Humanity's Last Exam | 13.2% | 61.4% |
| MMMU-Pro (visual reasoning) | 71.2% | 87.7% |
| Long-context reasoning (AA-LCR) | 70.7% | 84.7% |
| Terminal-Bench Hard | 40.9% | No data |
| GPQA Diamond | 81% | No data |
| IFBench (instruction following) | 43% | No data |
| τ²-Bench (agentic tool use) | 86.3% | No data |
| Intelligence Index | No data | 57.6 |
| SciCode | No data | 66.9% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Claude Opus 4.5 or Claude Opus 5.5?
Choose Claude Opus 5.5 for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), very long inputs, reasoning over long documents and the latest release; on the other points the two are level or the data is missing.
Which is cheaper, Claude Opus 4.5 or Claude Opus 5.5?
Claude Opus 5.5 is 20% cheaper than Claude Opus 4.5 at the headline price ($8.00 / 1M tokens vs $10.00 / 1M tokens).
Which has the larger context window, Claude Opus 4.5 or Claude Opus 5.5?
Claude Opus 5.5 reads more per request: 1M tokens against 200k.
What is the difference between Claude Opus 4.5 and Claude Opus 5.5?
Claude Opus 4.5 is made by Anthropic and Claude Opus 5.5 by Anthropic. Claude Opus 5.5 is 20% cheaper than Claude Opus 4.5 at the headline price ($8.00 / 1M tokens vs $10.00 / 1M tokens). Claude Opus 5.5 reads more per request: 1M tokens against 200k. Claude Opus 5.5 is the newer model (September 2026, against November 2025).
How much do Claude Opus 4.5 and Claude Opus 5.5 cost per month?
At 20 million input and 5 million output tokens a month, Claude Opus 4.5 costs $225.00 and Claude Opus 5.5 costs $180.00, at standard rates.
Which is newer, Claude Opus 4.5 or Claude Opus 5.5?
Claude Opus 5.5 was released on September 2026 and Claude Opus 4.5 on November 2025.