Noometry

Model comparison

Claude Opus 5 vs GPT-5.1-Codex-mini

Claude Opus 5 has enough public results to be ranked (#4); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.

Last verified . 1 shared benchmarks.

Claude Opus 5 Anthropic

67.7

Rank #4 Confirmed

GPT-5.1-Codex-mini OpenAI

36.9

Unranked Sparse

Summary

  • They share 1 benchmark with published results for both. Claude Opus 5 scores higher in 2 categories and GPT-5.1-Codex-mini in 0 categories; 2 gaps are clear of the uncertainty.
  • The widest gap is in coding, where Claude Opus 5 leads 67.0 to 31.4.
  • GPT-5.1-Codex-mini is cheaper at $0.25 / $2 per million input/output tokens, against $5 / $25 for Claude Opus 5.
  • Claude Opus 5 accepts more context: 1M tokens versus 400K.

Side by side

Claude Opus 5GPT-5.1-Codex-mini
ProviderAnthropicOpenAI
Noometry Index67.736.9
Released2026-07-242025-11-12
WeightsProprietaryProprietary
Context window1M400K
Max output128K128K
Input $ / M tokens$5$0.25
Output $ / M tokens$25$2
Results tracked572

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Category by category

Coding Claude Opus 5 leads

Claude Opus 5: 67.0 (#5), GPT-5.1-Codex-mini: 31.4

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
LMArena WebDev16941244
DeepSWE73.6%—
FrontierCode53.4%—
CursorBench46.6%—
FrontierSWE52%—
SciCode56.4%—
WeirdML91.8%—
LMArena Coding1533—
ALE-Bench2,165—

Agentic & Tool Use Claude Opus 5 leads

Claude Opus 5: 55.5 (#1), GPT-5.1-Codex-mini: 38.3

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
Terminal-Bench—61.6%
APEX-Agents65.8%—
OSWorld 2.031.4%—
τ²-bench Banking48.7%—
PostTrainBench35%—
BALROG63.4%—
GBAEval79.6%—
GDP.pdf24%—
Vending-Bench 211,182—

Reasoning Not comparable

Claude Opus 5: 77.1 (#3), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
ARC-AGI-290.4%—
SimpleBench80.6%—
NYT Connections (extended)94.3%—
ARC-AGI-197.5%—
CritPt29.1%—
Chess Puzzles42%—
EBR-Bench45.7%—
LMArena Hard Prompts1525—
Mystery Game Puzzles59%—
DTBench97.9%—
LMCA64.5%—
Bench to the Future 30.12—
Epoch Capabilities Index162.67—

Math Not comparable

Claude Opus 5: 86.1 (#6), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
FrontierMath (Tiers 1-3)85.6%—
FrontierMath Tier 473.2%—
OTIS Mock AIME 2024-202598.9%—
ProofBench99%—
LMArena Math1533—

Knowledge Not comparable

Claude Opus 5: 66.8 (#8), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
GPQA Diamond93.9%—
SimpleQA Verified59.9%—
LMArena Expert1558—

Multimodal Not comparable

Claude Opus 5: 51.1 (#6), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
LMArena Vision1321—
Blueprint-Bench 230.4%—
Furniture Assembly60.8%—
LMArena Document1516—

Multilingual Not comparable

Claude Opus 5: 58.8 (#3), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
LMArena Non-English1500—
LMArena Chinese1575—
LMArena French1522—
LMArena German1522—
LMArena Japanese1510—
LMArena Korean1526—
LMArena Russian1507—
LMArena Spanish1519—

Instruction Following Not comparable

Claude Opus 5: 79.3 (#5), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
LMArena Instruction Following1516—

Long Context Not comparable

Claude Opus 5: 46.5 (#20), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
LMArena Longer Query1516—

Writing & Preference Not comparable

Claude Opus 5: 79.3 (#2), GPT-5.1-Codex-mini: —

BenchmarkClaude Opus 5GPT-5.1-Codex-mini
LMArena Text1506—
LMArena Creative Writing1491—
EQ-Bench Creative Writing2133—
EQ-Bench 41385—
LMArena Multi-Turn1496—

Frequently asked questions

Is Claude Opus 5 better than GPT-5.1-Codex-mini?

Claude Opus 5 has enough public results to be ranked (#4); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.

Which is cheaper, Claude Opus 5 or GPT-5.1-Codex-mini?

GPT-5.1-Codex-mini is cheaper. It lists at $0.25 per million input tokens and $2 per million output tokens; Claude Opus 5 lists at $5 and $25.

Is Claude Opus 5 or GPT-5.1-Codex-mini better for coding?

Claude Opus 5 scores higher on coding benchmarks: 67.0 versus 31.4 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 5 does, with 1M tokens against 400K.

How many benchmarks do Claude Opus 5 and GPT-5.1-Codex-mini share?

1 benchmark has published results for both models. Claude Opus 5 has 57 scored results on Noometry and GPT-5.1-Codex-mini has 2.

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