Inference
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OpenAI

GPT-5.1-Codex

GPT-5.1-Codex is a reasoning model from OpenAI. 15 benchmarks count toward its index, in 6 categories.

  • Closed weights
  • Reasoning
  • Input: text · image
  • Released 2025-11
RankedEnough results for an index.
IndexAll categories, out of 100.52.9±5.7Median 51.0
CoverageIndex weight that has results.85%
SpeedOutput tokens per second.55/sMedian 67/s
First tokenSeconds to the first output token.4.0 sMedian 1.3 s
Input / 1MUS dollars per 1M input tokens.$1.25Median $0.60
Output / 1MUS dollars per 1M output tokens.$10.00Median $2.55
ContextMaximum tokens in one request.400KMedian 262K
EloLMArena rating and rank.—Median 1422

Details

From OpenRouter
API IDThe model ID on OpenRouter.
openai/gpt-5.1-codex
Max outputMaximum output tokens per request.
128K
Knowledge cutoffLast date of training data.
—
ToolsTool calls on OpenRouter.
Yes
JSON outputOutput follows a given JSON schema.
Yes
Cache read / 1MUS dollars per 1M cached tokens.
$0.13
WeightsLink to the published weights.
—
RetiresDate OpenRouter removes the model.
—

Where to run

APIs that serve this model.
1 provider
ProviderTypeMaker, cloud, host or router.InputOutputContext
OpenRouterRouter$1.25$10.00400K

US dollars per 1M tokens, list price. From models.dev (opens in a new tab) (MIT).

Capabilities

Index per category, out of 100.
Out of 100
AgenticMulti-step tasks with tools.4 counted56.195 / 218
CodingCode writing and repair.4 counted49.8139 / 209
ReasoningLogic problems and puzzles.2 counted51.4105 / 227
MultimodalTasks with images and text.1 counted49.5—
KnowledgeFacts and expert knowledge.3 counted55.790 / 268
MultilingualTasks in many languages.None counted——
InstructionTasks with strict prompt rules.1 counted54.4—
MathMath problems.None counted——

Results

15 counted
BenchmarkThe benchmark name.ResultThe score from the source.PlacePlace among results on this benchmark.
Terminal-Bench 1.0Agentic57.5% ±5.55 / 47
LiveCodeBenchCoding85.5% ±1.030 / 142
SWE-bench Verified · SWE-bench/experimentsCoding66.0%19 / 65
Artificial Analysis IFBenchInstruction70.0%46 / 146
Artificial Analysis Omniscience AccuracyKnowledge39.9%52 / 164
Artificial Analysis GPQA DiamondKnowledge86.0%68 / 199
Critical Physics TasksReasoning5.7%78 / 214
Gert Labs Composite Game BenchmarkAgentic49.7%22 / 52
τ²-Bench Tool-Agent-User EvaluationAgentic83.0%64 / 149
Artificial Analysis Humanity's Last ExamKnowledge25.7%96 / 222
Artificial Analysis Long Context ReasoningReasoning69.3%115 / 217
Artificial Analysis MMMU-ProMultimodal72.5%69 / 113
JobBenchAgentic26.2%27 / 36
Vibe Code Bench v1.1Coding13.1% ±3.2102 / 123
IOI v1Coding3.7% ±3.351 / 61

Sources

BenchLMCC BY-NC 4.0OpenRouterTerms restrict reuseVals AINo licence statedSWE-bench teamNo licence statedmodels.devMIT

History

5 releases
Index54.0 → 52.9
23 Oct 202612 Nov 2026
Output / 1M$10.00 → $10.00
23 Oct 202612 Nov 2026

Questions

How much does GPT-5.1-Codex cost?
$1.25 per 1M input tokens, $10.00 per 1M output tokens.
How good is GPT-5.1-Codex?
Its index is 52.9 out of 100. That is place 120 of 283 ranked models.
What is GPT-5.1-Codex best at?
Knowledge: 55.7 out of 100, place 90 of 268.
How fast is GPT-5.1-Codex?
55 output tokens per second, 4.0 s to the first token.
What is the context window of GPT-5.1-Codex?
400K tokens.
Is GPT-5.1-Codex open source?
No. Its weights are not published.
When was GPT-5.1-Codex released?
November 2025.

Badge

GPT-5.1-Codex on Inference360: place 120 of 283, index 52.9
HTML
<a href="https://inference360.ai/models/gpt-5-1-codex"><img src="https://inference360.ai/badges/gpt-5-1-codex.svg" alt="GPT-5.1-Codex on Inference360: place 120 of 283, index 52.9" height="20"></a>
Markdown
[![GPT-5.1-Codex on Inference360: place 120 of 283, index 52.9](https://inference360.ai/badges/gpt-5-1-codex.svg)](https://inference360.ai/models/gpt-5-1-codex)

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