Claude Sonnet 4.5 vs GPT-5.1
Anthropic vs OpenAI — benchmarks, pricing, and capabilities side by side.
- •GPT-5.1 has the higher intelligence index (89 vs 80.4)
- •GPT-5.1 is cheaper ($1.25 vs $3.00 per 1M input)
- •GPT-5.1 is faster
- •Claude Sonnet 4.5 has a larger context window (1M)
| Claude Sonnet 4.5 | GPT-5.1 | |
|---|---|---|
| Intelligence index | 80.4 | 89 |
| Developer | Anthropic | OpenAI |
| Type | LLM | LLM |
| Access | API only | API only |
| Context window | 1,000,000 tokens | 400,000 tokens |
| Input price | $3.00 / 1M | $1.25 / 1M |
| Output price | $15.00 / 1M | $10.00 / 1M |
| Speed | 42 tok/s | 115 tok/s |
| Released | September 29, 2025 | November 12, 2025 |
| Parameters | — | — |
| Input modalities | Text, Image | Text, Image |
| Output modalities | Text | Text |
Shared benchmarks
Claude Sonnet 4.5
GPT-5.1
AIME 2025
87
94
GPQA Diamond
83.4
88.1
Humanity’s Last Exam
17.3
26.5
LiveCodeBench
71.4
86.8
MMLU-Pro
87.5
87