Noometry

Model comparison

GPT-5.1-Codex vs Qwen3.5-Flash

Qwen3.5-Flash is the stronger model overall, scoring 42.5 to 38.6 on the Noometry Index.

Last verified . 2 shared benchmarks.

GPT-5.1-Codex OpenAI

38.6

Rank #186 Reported

Qwen3.5-Flash Alibaba (Qwen)

42.5

Rank #112 Confirmed

Summary

  • They share 2 benchmarks with published results for both. GPT-5.1-Codex scores higher in 1 category and Qwen3.5-Flash in 1 category; 2 gaps are clear of the uncertainty.
  • The widest gap is in coding, where GPT-5.1-Codex leads 41.9 to 34.2.
  • Qwen3.5-Flash is cheaper at $0.10 / $0.40 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
  • Qwen3.5-Flash accepts more context: 1M tokens versus 400K.

Side by side

GPT-5.1-CodexQwen3.5-Flash
ProviderOpenAIAlibaba (Qwen)
Noometry Index38.642.5
Released2025-11-122026-02-23
WeightsProprietaryProprietary
Context window400K1M
Max output128K66K
Input $ / M tokens$1.25$0.10
Output $ / M tokens$10$0.40
Results tracked632

Sponsored placements are available on pages like this one. Advertise on Noometry

Category by category

Coding GPT-5.1-Codex leads

GPT-5.1-Codex: 41.9 (#116), Qwen3.5-Flash: 34.2 (#242)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
LMArena WebDev13371244
ALE-Bench1,245221.8
SWE-bench Verified (bash only)66%—
LMArena Coding—1412

Agentic & Tool Use Not comparable

GPT-5.1-Codex: 38.0 (#33), Qwen3.5-Flash: —

BenchmarkGPT-5.1-CodexQwen3.5-Flash
Terminal-Bench60.4%—
METR Time Horizons70.8%—
Vending-Bench 2—462.69

Reasoning Not comparable

GPT-5.1-Codex: —, Qwen3.5-Flash: 33.7 (#72)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
Chess Puzzles—21%
LMArena Hard Prompts—1403
Mystery Game Puzzles—20%
DTBench—82.9%
LMCA—29.1%
Epoch Capabilities Index—143.98

Math Qwen3.5-Flash leads

GPT-5.1-Codex: 30.3 (#235), Qwen3.5-Flash: 37.4 (#158)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
FrontierMath (Tiers 1-3)—18.2%
OTIS Mock AIME 2024-2025—84.4%
ProofBench9%—
LMArena Math—1407
FrontierMath (Feb 2025 set)—6.2%
FrontierMath Tier 4 (v1)—0%

Knowledge Not comparable

GPT-5.1-Codex: —, Qwen3.5-Flash: 43.2 (#93)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
GPQA Diamond—82.3%
SimpleQA Verified—20.3%
Vectara Hallucination Rate—10.5%
LMArena Expert—1407

Multilingual Not comparable

GPT-5.1-Codex: —, Qwen3.5-Flash: 50.5 (#121)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
LMArena Non-English—1385
LMArena Chinese—1446
LMArena French—1412
LMArena German—1390
LMArena Japanese—1368
LMArena Korean—1344
LMArena Russian—1379
LMArena Spanish—1400

Instruction Following Not comparable

GPT-5.1-Codex: —, Qwen3.5-Flash: 72.6 (#139)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
LMArena Instruction Following—1374

Long Context Not comparable

GPT-5.1-Codex: —, Qwen3.5-Flash: 42.4 (#124)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
LMArena Longer Query—1392

Writing & Preference Not comparable

GPT-5.1-Codex: —, Qwen3.5-Flash: 57.9 (#122)

BenchmarkGPT-5.1-CodexQwen3.5-Flash
LMArena Text—1397
LMArena Creative Writing—1343
LMArena Multi-Turn—1393

Frequently asked questions

Is GPT-5.1-Codex better than Qwen3.5-Flash?

Qwen3.5-Flash is the stronger model overall, scoring 42.5 to 38.6 on the Noometry Index.

Which is cheaper, GPT-5.1-Codex or Qwen3.5-Flash?

Qwen3.5-Flash is cheaper. It lists at $0.10 per million input tokens and $0.40 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.

Is GPT-5.1-Codex or Qwen3.5-Flash better for coding?

GPT-5.1-Codex scores higher on coding benchmarks: 41.9 versus 34.2 in the Noometry coding category.

Which has the bigger context window?

Qwen3.5-Flash does, with 1M tokens against 400K.

How many benchmarks do GPT-5.1-Codex and Qwen3.5-Flash share?

2 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Qwen3.5-Flash has 32.

Related comparisons

Go deeper