Claude Opus 4.1 vs Claude Opus 4.5
Arena Text · creative writing Arena Text · creative writing: Human pairwise preferences in the stated text vote pool
Opus 4.11,446
Opus 4.5 · high1,469
EQ-Bench Longform Creative Writing 1.11 Longform Creative Writing 1.11: Models plan, revise and write a story across eight turns, graded with a writing rubric
Opus 4.170.5
Opus 4.573.1
IFBench (instructions) IFBench (instructions): Checks whether the model follows precise formatting and content instructions
Opus 4.155.4
Opus 4.543
EQ-Bench Creative Writing v3 Creative Writing v3 · Elo: Judge-rated creative writing under the v3 prompt set and pairwise ranking
Opus 4.1—
Opus 4.51,686.7
| Benchmark | Opus 4.1 | Opus 4.5 |
|---|---|---|
| Arena Text · creative writing | 1,446 | 1,469 · high |
| EQ-Bench Longform Creative Writing 1.11 | 70.5 | 73.1 |
| IFBench (instructions) | 55.4 | 43 |
| EQ-Bench Creative Writing v3 | — | 1,686.7 |
Specs
| Spec | Opus 4.1 | Opus 4.5 |
|---|---|---|
| Input, per 1M | $15 | $5 |
| Output, per 1M | $75 | $25 |
| Speed, tok/s | — | 51 |
| Context | 200K | 200K |
| Weights | Closed | Closed |
| Released | Aug 2025 | Nov 2025 |
| See images | ✓ | ✓ |
| Read PDFs | Partial | Partial |
| Hear audio | — | — |
| Watch video | — | — |
| Call tools | ✓ | ✓ |
| Force a tool call | Partial | Partial |
| Return strict JSON | — | ✓ |
| Search the web | ? | ? |
| Run code | ? | ? |
| Use a computer | ? | ? |
What breaks when you switch
Opus 4.1 → Opus 4.5
Nothing known.
Opus 4.5 → Opus 4.1