Claude Sonnet 4.5 vs o1
Claude Sonnet 4.5 significantly outperforms across most benchmarks. Claude Sonnet 4.5 is 4.4x cheaper per token.
Anthropic · OpenAI · Updated for 2026
Which is better?
Claude Sonnet 4.5 outperforms in 4 benchmarks (GPQA, MMMLU, TAU-bench Airline, TAU-bench Retail), while o1 is better at 0 benchmarks. Claude Sonnet 4.5 significantly outperforms across most benchmarks.
On price, Claude Sonnet 4.5 is roughly 4.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Based on current benchmark, pricing, and model metadata for 2026.
Choose Claude Sonnet 4.5
- you want the strongest raw capability — it leads on 4 of 4 shared benchmarks
- cost matters — it's about 4.4x cheaper per token
- you want the most recent training data — it shipped Sep 2025
Choose o1
- you want predictable pricing at $15.00/M input and $60.00/M output
At a glance
The differences that matter most.
Performance Benchmarks
Comparative analysis across standard metrics
Claude Sonnet 4.5 outperforms in 4 benchmarks (GPQA, MMMLU, TAU-bench Airline, TAU-bench Retail), while o1 is better at 0 benchmarks.
Claude Sonnet 4.5 significantly outperforms across most benchmarks.
Arena Performance
Playground indexes and blind preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Sonnet 4.5 ($3.00/1M tokens) is 5.0x cheaper than o1 ($15.00/1M tokens).
For output processing, Claude Sonnet 4.5 ($15.00/1M tokens) is 4.0x cheaper than o1 ($60.00/1M tokens).
In conclusion, o1 is more expensive than Claude Sonnet 4.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Both models have the same input context window of 200,000 tokens. o1 can generate longer responses up to 100,000 tokens, while Claude Sonnet 4.5 is limited to 64,000 tokens.
Input Capabilities
Supported data types and modalities
Claude Sonnet 4.5 supports multimodal inputs, whereas o1 does not.
Claude Sonnet 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.
Claude Sonnet 4.5
o1
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Claude Sonnet 4.5 was released on 2025-09-29, while o1 was released on 2024-12-17.
Claude Sonnet 4.5 is 10 months newer than o1.
Sep 29, 2025
11 months ago
9mo newerDec 17, 2024
1.7 years ago
Knowledge Cutoff
When training data ends
Claude Sonnet 4.5 has a documented knowledge cutoff of 2025-01-31, while o1's cutoff date is not specified.
We can confirm Claude Sonnet 4.5's training data extends to 2025-01-31, but cannot make a direct comparison without o1's cutoff date.
Jan 2025
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Provider Availability
Claude Sonnet 4.5 is available from Anthropic. o1 is available from Azure, OpenAI.
Claude Sonnet 4.5
o1
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Sonnet 4.5 and o1 side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Sonnet 4.5 vs o1.