AI model comparison
GPT-5.1 vs GPT-5.1-Codex
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
OpenAI
GPT-5.1
GPT-5.1 is the latest frontier-grade model in the GPT-5 series, offering stronger general-purpose reasoning, improved instruction adherence, and a more natural conversational style compared to GPT-5.
- Input / 1M
- $1.25
- Output / 1M
- $10
- Context
- 400K
OpenAI
GPT-5.1-Codex
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows.
- Input / 1M
- $1.25
- Output / 1M
- $10
- Context
- 400K
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
Tie
Same price for a typical chat
Higher intelligence score
GPT-5.1
24.7 vs 23.7 on Artificial Analysis
Larger context window
Tie
400K vs 400K tokens
Newer release
GPT-5.1
Released November 13, 2025
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
GPT-5.124.7GPT-5.1-Codex23.7Coding index
GPT-5.149.4GPT-5.1-CodexNot availableAgentic index
GPT-5.1Not availableGPT-5.1-CodexNot availablePricing
GPT-5.1 vs GPT-5.1-Codex API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | GPT-5.1 | GPT-5.1-Codex |
|---|---|---|
| Input tokensPer 1M tokens | $1.25 | $1.25 |
| Output tokensPer 1M tokens | $10 | $10 |
| Cached input (read)Per 1M tokens | $0.13 | $0.13 |
| Cache writePer 1M tokens | Not available | Not available |
| Web searchPer request | $0.01 | $0.01 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
GPT-5.1$7.50GPT-5.1-Codex$7.50Coding task
30K in, 4K out
GPT-5.1$77.50$43.75 cachedGPT-5.1-Codex$77.50$43.90 cachedLong document summary
150K in, 2K out
GPT-5.1$207.50$38.75 cachedGPT-5.1-Codex$207.50$39.50 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | GPT-5.1 | GPT-5.1-Codex |
|---|---|---|
| Context window | 400K tokens | 400K tokens |
| Max output | 128K tokens | 128K tokens |
| Input types | File, Image, Text | Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | High, Medium, Low, None | High, Medium, Low |
| Default reasoning effort | None | Medium |
| Release date | November 13, 2025 | November 13, 2025 |
Features
Supported features
API features available for each model.
| Metric | GPT-5.1 | GPT-5.1-Codex |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Not supported |
| Stop sequences | Not supported | Not supported |
| Deterministic seed | Supported | Supported |
| Verbosity control | Supported | Supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
GPT-5.1-CodexView full model details- GPT-5.1-Codex vs GPT-5.2
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- GPT-5.1-Codex vs Gemini 3 Flash Preview
- GPT-5.1-Codex vs DeepSeek V4 Flash 0423
- GPT-5.1-Codex vs GPT-5.4 Mini
- GPT-5.1-Codex vs GPT-5
- GPT-5.1-Codex vs Claude Opus 4.1
- GPT-5.1-Codex vs o3 Pro
- GPT-5.1-Codex vs Claude Sonnet 4.5
- GPT-5.1-Codex vs GPT-5 Mini
- GPT-5.1-Codex vs o3
- GPT-5.1-Codex vs Claude Sonnet 4
Our take
GPT-5.1 scores higher on the Artificial Analysis Intelligence Index (24.7 vs 23.7). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is GPT-5.1 or GPT-5.1-Codex cheaper?
GPT-5.1 and GPT-5.1-Codex cost the same for a typical chat (2K input tokens and 500 output tokens). GPT-5.1 costs $1.25 per 1M input tokens and $10 per 1M output tokens, and GPT-5.1-Codex costs $1.25 per 1M input tokens and $10 per 1M output tokens.
Which has a bigger context window, GPT-5.1 or GPT-5.1-Codex?
GPT-5.1 supports up to 400K tokens of context, compared with 400K for GPT-5.1-Codex.
Is GPT-5.1 smarter than GPT-5.1-Codex?
On the Artificial Analysis Intelligence Index, GPT-5.1 scores 24.7 and GPT-5.1-Codex scores 23.7, putting GPT-5.1 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use GPT-5.1 and GPT-5.1-Codex at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see GPT-5.1 and GPT-5.1-Codex answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to GPT-5.1 and GPT-5.1-Codex at the same time. Compare the answers side by side and keep the best one.