Noometry

Model comparison

Gemini 3.8 Flash vs GPT-5.1-Codex-mini

Gemini 3.8 Flash has enough public results to be ranked (#13); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.

Last verified . 1 shared benchmarks.

Gemini 3.8 Flash Google

59.5

Rank #13 Confirmed

GPT-5.1-Codex-mini OpenAI

36.9

Unranked Sparse

Summary

  • They share 1 benchmark with published results for both. Gemini 3.8 Flash 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 Gemini 3.8 Flash leads 56.4 to 31.4.
  • GPT-5.1-Codex-mini is cheaper at $0.25 / $2 per million input/output tokens, against $0.75 / $3.75 for Gemini 3.8 Flash.
  • Gemini 3.8 Flash accepts more context: 1.05M tokens versus 400K.

Side by side

Gemini 3.8 FlashGPT-5.1-Codex-mini
ProviderGoogleOpenAI
Noometry Index59.536.9
Released2026-09-022025-11-12
WeightsProprietaryProprietary
Context window1.05M400K
Max output66K128K
Input $ / M tokens$0.75$0.25
Output $ / M tokens$3.75$2
Results tracked462

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Category by category

Coding Gemini 3.8 Flash leads

Gemini 3.8 Flash: 56.4 (#17), GPT-5.1-Codex-mini: 31.4

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
LMArena WebDev15811244
DeepSWE73.8%—
FrontierCode41.2%—
CursorBench39.6%—
FrontierSWE19.6%—
SciCode56.6%—
LMArena Coding1512—
ALE-Bench1,270—

Agentic & Tool Use Gemini 3.8 Flash leads

Gemini 3.8 Flash: 40.3 (#22), GPT-5.1-Codex-mini: 38.3

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
Terminal-Bench—61.6%
APEX-Agents64.3%—
GDP.pdf23.4%—
Vending-Bench 25,094—

Reasoning Not comparable

Gemini 3.8 Flash: 64.7 (#13), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
NYT Connections (extended)97.4%—
CritPt18.3%—
Chess Puzzles61%—
LMArena Hard Prompts1506—
Mystery Game Puzzles47%—
DTBench95.7%—
LMCA52.9%—
Surface Evolver Bench76.9%—
Epoch Capabilities Index157.13—

Math Not comparable

Gemini 3.8 Flash: 65.2 (#22), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
FrontierMath (Tiers 1-3)68.4%—
FrontierMath Tier 422%—
OTIS Mock AIME 2024-202598.9%—
ProofBench48%—
LMArena Math1528—

Knowledge Not comparable

Gemini 3.8 Flash: 74.9 (#2), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
GPQA Diamond95.4%—
Humanity's Last Exam44.5%—
SimpleQA Verified69.7%—
LMArena Expert1529—

Multimodal Not comparable

Gemini 3.8 Flash: 40.9 (#33), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
LMArena Vision1312—
Blueprint-Bench 238.6%—
Furniture Assembly31.7%—

Multilingual Not comparable

Gemini 3.8 Flash: 57.9 (#5), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
LMArena Non-English1486—
LMArena Chinese1547—
LMArena French1502—
LMArena German1470—
LMArena Japanese1505—
LMArena Korean1479—
LMArena Russian1507—
LMArena Spanish1492—

Instruction Following Not comparable

Gemini 3.8 Flash: 78.2 (#11), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
LMArena Instruction Following1489—

Long Context Not comparable

Gemini 3.8 Flash: 46.2 (#23), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
LMArena Longer Query1506—

Writing & Preference Not comparable

Gemini 3.8 Flash: 72.1 (#16), GPT-5.1-Codex-mini: —

BenchmarkGemini 3.8 FlashGPT-5.1-Codex-mini
LMArena Text1494—
LMArena Creative Writing1485—
EQ-Bench Creative Writing1748—
LMArena Multi-Turn1503—

Frequently asked questions

Is Gemini 3.8 Flash better than GPT-5.1-Codex-mini?

Gemini 3.8 Flash has enough public results to be ranked (#13); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.

Which is cheaper, Gemini 3.8 Flash 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; Gemini 3.8 Flash lists at $0.75 and $3.75.

Is Gemini 3.8 Flash or GPT-5.1-Codex-mini better for coding?

Gemini 3.8 Flash scores higher on coding benchmarks: 56.4 versus 31.4 in the Noometry coding category.

Which has the bigger context window?

Gemini 3.8 Flash does, with 1.05M tokens against 400K.

How many benchmarks do Gemini 3.8 Flash and GPT-5.1-Codex-mini share?

1 benchmark has published results for both models. Gemini 3.8 Flash has 46 scored results on Noometry and GPT-5.1-Codex-mini has 2.

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