Noometry

Model comparison

Gemini 3.8 Flash vs GPT-5.3 Codex

Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 45.8 on the Noometry Index.

Last verified . 5 shared benchmarks.

Gemini 3.8 Flash Google

61.8

Rank #11 Confirmed

GPT-5.3 Codex OpenAI

45.8

Rank #69 Reported

Summary

  • They share 5 benchmarks with published results for both. Gemini 3.8 Flash scores higher in 1 category and GPT-5.3 Codex in 1 category; 2 gaps are clear of the uncertainty.
  • The widest gap is in coding, where Gemini 3.8 Flash leads 59.2 to 48.6.
  • The biggest single-benchmark swing is WeirdML: 84.8% for Gemini 3.8 Flash and 79.3% for GPT-5.3 Codex.
  • Gemini 3.8 Flash is cheaper at $0.75 / $3.75 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Codex.
  • Gemini 3.8 Flash accepts more context: 1.05M tokens versus 400K.

Side by side

Gemini 3.8 FlashGPT-5.3 Codex
ProviderGoogleOpenAI
Noometry Index61.845.8
Released2026-09-022026-02-05
WeightsProprietaryProprietary
Context window1.05M400K
Max output66K128K
Input $ / M tokens$0.75$1.75
Output $ / M tokens$3.75$14
Results tracked508

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Category by category

Coding Gemini 3.8 Flash leads

Gemini 3.8 Flash: 59.2 (#15), GPT-5.3 Codex: 48.6 (#56)

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
LMArena WebDev15841409
WeirdML84.8%79.3%
ALE-Bench1,2701,655
SWE-bench Verified—74.8%
DeepSWE73.8%—
FrontierCode41.2%—
CursorBench39.6%—
FrontierSWE19.6%—
SciCode56.6%—
LMArena Coding1510—

Agentic & Tool Use GPT-5.3 Codex leads

Gemini 3.8 Flash: 41.8 (#21), GPT-5.3 Codex: 48.0 (#9)

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
Vending-Bench 25,0945,940
Terminal-Bench—78.4%
APEX-Agents64.3%—
Remote Labor Index5.8%—
GDP.pdf23.4%—
METR Time Horizons—74.5%

Reasoning Not comparable

Gemini 3.8 Flash: 76.9 (#5), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
Epoch Capabilities Index156.71156.77
ARC-AGI-289.2%—
NYT Connections (extended)97.4%—
ARC-AGI-198.5%—
CritPt18.3%—
Chess Puzzles61%—
LMArena Hard Prompts1508—
Mystery Game Puzzles47%—
DTBench95.7%—
LMCA52.9%—
Surface Evolver Bench76.9%—

Math Not comparable

Gemini 3.8 Flash: 65.3 (#28), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
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: 74.8 (#2), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
GPQA Diamond95.4%—
Humanity's Last Exam44.5%—
SimpleQA Verified69.7%—
LMArena Expert1524—

Multimodal Not comparable

Gemini 3.8 Flash: 40.7 (#45), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
LMArena Vision1314—
Blueprint-Bench 238.6%—
Furniture Assembly31.7%—

Multilingual Not comparable

Gemini 3.8 Flash: 58.0 (#5), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
LMArena Non-English1491—
LMArena Chinese1554—
LMArena French1498—
LMArena German1493—
LMArena Japanese1502—
LMArena Korean1459—
LMArena Russian1515—
LMArena Spanish1485—

Instruction Following Not comparable

Gemini 3.8 Flash: 78.0 (#13), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
LMArena Instruction Following1490—

Long Context Not comparable

Gemini 3.8 Flash: 46.3 (#24), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
LMArena Longer Query1508—

Writing & Preference Not comparable

Gemini 3.8 Flash: 72.2 (#15), GPT-5.3 Codex: —

BenchmarkGemini 3.8 FlashGPT-5.3 Codex
LMArena Text1499—
LMArena Creative Writing1492—
EQ-Bench Creative Writing1748—
LMArena Multi-Turn1501—

Frequently asked questions

Is Gemini 3.8 Flash better than GPT-5.3 Codex?

Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 45.8 on the Noometry Index.

Which is cheaper, Gemini 3.8 Flash or GPT-5.3 Codex?

Gemini 3.8 Flash is cheaper. It lists at $0.75 per million input tokens and $3.75 per million output tokens; GPT-5.3 Codex lists at $1.75 and $14.

Is Gemini 3.8 Flash or GPT-5.3 Codex better for coding?

Gemini 3.8 Flash scores higher on coding benchmarks: 59.2 versus 48.6 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-5.3 Codex share?

5 benchmarks have published results for both models. Gemini 3.8 Flash has 50 scored results on Noometry and GPT-5.3 Codex has 8.

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