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Models · gpt-5

GPT-5.1

Proprietary OpenAI · 2025-11-12 · Proprietary

Released November 12 2025 with three initial models; two more (Codex-Mini, Codex-Max) followed November 19. Headline change is a warmer default tone plus eight selectable personalities. GPT-5.1 Instant gained adaptive reasoning, deciding per-turn whether to think before responding.

Cost

$1.25 / Mtok input
$10.00 / Mtok output

· as of 2026-05-21

source ↗

Speed

114.7 tok/sec output
27133 ms TTFT

· as of 2026-05-21

source ↗

Architecture

tokens in Embedding vocab not disclosed × N layers Architecture not disclosed (proprietary or undocumented) Output projection tokens out
Schema-generated from data/models.yaml. Every label is auditable against the model's sources.

Specs

Architecture
unknown
Total params
not disclosed
Active params
not disclosed
Context window
400K tokens
Attention
unknown
Position encoding
unknown
Post-training
rlhf
OSI-approved
no
Data released
no
Training code
not released

Benchmarks

Each score carries the date it was published; we never infer or interpolate missing scores.

General reasoning

MMLU-Pro 87.0 as of 2026-05-21 source ↗
GPQA-Diamond 87.3 as of 2026-05-21 source ↗

Code

LiveCodeBench 86.8 as of 2026-05-21 source ↗

Math

AIME 2025 94.0 as of 2026-05-21 source ↗

Available quantizations

None. The weights are not distributed, so there are no public quantizations.

Notable innovations

  • · Eight selectable personality presets
  • · Adaptive reasoning in Instant mode
  • · GPT-5.1-Codex-Max for long-horizon agentic coding

Lineage

Tone and personality update, plus the Codex-Max agentic-coding variant.

Derived from

GPT-5 2025-08-07

Sources