GPT-5.1 Chat vs GPT-5.1-Codex
| Signal | GPT-5.1 Chat | Delta | GPT-5.1-Codex |
|---|---|---|---|
Capabilities | 83 | -17 | |
Benchmarks | 88 | -- | |
Pricing | 90 | -- | |
Context window size | 73 | -7 | |
Recency | 89 | -- | |
Output Capacity | 75 | -10 | |
| Overall Result | 0 wins | of 6 | 3 wins |
Score History
88.2
current score
Tied
right now
88.2
current score
GPT-5.1 Chat
OpenAI
GPT-5.1-Codex
OpenAI
| Metric | GPT-5.1 Chat | GPT-5.1-Codex | Winner |
|---|---|---|---|
| Overall Score | 88 | 88 | -- |
| Rank | #30 | #31 | GPT-5.1 Chat |
| Quality Rank | #30 | #31 | GPT-5.1 Chat |
| Adoption Rank | #30 | #31 | GPT-5.1 Chat |
| Parameters | -- | -- | -- |
| Context Window | 128K | 400K | GPT-5.1-Codex |
| Pricing | $1.25/$10.00/M | $1.25/$10.00/M | -- |
| Signal Scores | |||
| Capabilities | 83 | 100 | GPT-5.1-Codex |
| Benchmarks | 88 | 88 | GPT-5.1 Chat |
| Pricing | 90 | 90 | GPT-5.1 Chat |
| Context window size | 73 | 80 | GPT-5.1-Codex |
| Recency | 89 | 89 | GPT-5.1 Chat |
| Output Capacity | 75 | 85 | GPT-5.1-Codex |
Our score (0-100) is driven by benchmark performance (90%) from Arena Elo ratings, MMLU, GPQA, HumanEval, SWE-bench, and 15+ standardized evaluations. Capabilities and context window serve as tiebreakers (10%). Learn more about our methodology.
Scores 88/100 (rank #30), placing it in the top 90% of all 290 models tracked.
Scores 88/100 (rank #31), placing it in the top 90% of all 290 models tracked.
With only a 0-point gap, these models are in the same performance tier. The practical difference in output quality is minimal - your choice should depend on pricing, latency requirements, and specific feature needs.
Choose GPT-5.1 Chat when you need:
- General-purpose tasks across coding, writing, and analysis
Choose GPT-5.1-Codex when you need:
- Processing long documents or large codebases (400K token context)
- Step-by-step reasoning and chain-of-thought problem solving
Both models are priced similarly, so the decision comes down to quality and features rather than cost.
Both models have comparable response speeds. For most applications, the latency difference is negligible.
When latency matters most: Interactive chatbots, IDE code completion, real-time translation, and user-facing applications where response time directly impacts experience. For batch processing, background summarization, or offline analysis, latency is less critical.
Code generation & review
Based on overall model capabilities and architecture for coding tasks like generating functions, debugging, and refactoring
Customer support chatbot
Suitable for user-facing chat with competitive response times. GPT-5.1 Chat also offers lower per-token costs for high-volume support
Long document analysis
Larger context window (400K tokens) can process longer documents, contracts, and research papers in a single pass
Batch data extraction
Lower output pricing ($10.00/M) reduces costs when processing thousands of records daily
Creative writing & content
Higher overall composite score (88/100) correlates with better nuance, coherence, and style in long-form content
Image understanding & OCR
Supports vision input - can analyze screenshots, diagrams, photos, and scanned documents directly
GPT-5.1 Chat and GPT-5.1-Codex are extremely close in overall performance (only 0 points apart). Your best choice depends entirely on which specific strengths matter most for your use case.
By Use Case
Best for Quality
GPT-5.1 Chat
Marginally better benchmark scores; both are excellent
Best for Cost
GPT-5.1 Chat
0% lower pricing; better value at scale
Best for Reliability
GPT-5.1 Chat
Higher uptime and faster response speeds
Best for Prototyping
GPT-5.1 Chat
Stronger community support and better developer experience
Best for Production
GPT-5.1 Chat
Wider enterprise adoption and proven at scale
by OpenAI
- Choose for Quality - Marginally better benchmark scores; both are excellent
- Choose for Cost - 0% lower pricing; better value at scale
- Choose for Reliability - Higher uptime and faster response speeds
- Choose for Prototyping - Stronger community support and better developer experience
- Choose for Production - Wider enterprise adoption and proven at scale
| Capability | GPT-5.1 Chat | GPT-5.1-Codex |
|---|---|---|
| Vision (Image Input) | ||
| Function Calling | ||
| Streaming | ||
| JSON Mode | ||
| Reasoningdiffers | ||
| Web Search | ||
| Image Output |
GPT-5.1 Chat
OpenAI
GPT-5.1-Codex
OpenAI
Assumes 60% input / 40% output token ratio per request. Actual costs may vary based on your usage pattern.
| Parameter | GPT-5.1 Chat | GPT-5.1-Codex |
|---|---|---|
| Context Window | 128K | 400K |
| Max Output Tokens | 32,000 | 128,000 |
| Open Source | No | No |
| Created | Nov 13, 2025 | Nov 13, 2025 |