Model comparison

GPT-5.1-Codex vs Phi 3 Medium 4k Instruct

GPT-5.1-Codex is the stronger model overall, scoring 38.6 to 33.0 on the Noometry Index.

Last verified . 0 shared benchmarks.

GPT-5.1-Codex OpenAI

38.6

Rank #186 Reported

Phi 3 Medium 4k Instruct Microsoft

33.0

Rank #250 Confirmed

Summary

  • The widest gap is in coding, where GPT-5.1-Codex leads 41.9 to 32.9.
  • Phi 3 Medium 4k Instruct has downloadable open weights; the other is API-only.

Side by side

GPT-5.1-Codex and Phi 3 Medium 4k Instruct specifications
GPT-5.1-CodexPhi 3 Medium 4k Instruct
ProviderOpenAIMicrosoft
Noometry Index38.633.0
Released2025-11-12—
WeightsProprietaryOpen
Context window400K—
Max output128K—
Input $ / M tokens$1.25—
Output $ / M tokens$10—
Results tracked617

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Category by category

Coding GPT-5.1-Codex leads

GPT-5.1-Codex: 41.9 (#116), Phi 3 Medium 4k Instruct: 32.9 (#268)

Coding benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
SWE-bench Verified (bash only)66%—
LMArena WebDev1337—
LMArena Coding—1130
ALE-Bench1,245—

Agentic & Tool Use Not comparable

GPT-5.1-Codex: 38.0 (#33), Phi 3 Medium 4k Instruct: —

Agentic & Tool Use benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
Terminal-Bench60.4%—
METR Time Horizons70.8%—

Reasoning Not comparable

GPT-5.1-Codex: —, Phi 3 Medium 4k Instruct: 21.7 (#214)

Reasoning benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
LMArena Hard Prompts—1127

Math Phi 3 Medium 4k Instruct leads

GPT-5.1-Codex: 30.3 (#235), Phi 3 Medium 4k Instruct: 33.4 (#202)

Math benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
ProofBench9%—
LMArena Math—1173

Knowledge Not comparable

GPT-5.1-Codex: —, Phi 3 Medium 4k Instruct: 30.2 (#229)

Knowledge benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
LMArena Expert—1108

Multilingual Not comparable

GPT-5.1-Codex: —, Phi 3 Medium 4k Instruct: 30.6 (#263)

Multilingual benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
LMArena Non-English—1094
LMArena Chinese—1108
LMArena French—1110
LMArena German—1101
LMArena Japanese—1042
LMArena Korean—954
LMArena Russian—1145
LMArena Spanish—1095

Instruction Following Not comparable

GPT-5.1-Codex: —, Phi 3 Medium 4k Instruct: 57.6 (#268)

Instruction Following benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
LMArena Instruction Following—1113

Long Context Not comparable

GPT-5.1-Codex: —, Phi 3 Medium 4k Instruct: 34.0 (#255)

Long Context benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
LMArena Longer Query—1120

Writing & Preference Not comparable

GPT-5.1-Codex: —, Phi 3 Medium 4k Instruct: 34.1 (#272)

Writing & Preference benchmarks
BenchmarkGPT-5.1-CodexPhi 3 Medium 4k Instruct
LMArena Text—1138
LMArena Creative Writing—1107
LMArena Multi-Turn—1088

Frequently asked questions

Is GPT-5.1-Codex better than Phi 3 Medium 4k Instruct?

GPT-5.1-Codex is the stronger model overall, scoring 38.6 to 33.0 on the Noometry Index.

Is GPT-5.1-Codex or Phi 3 Medium 4k Instruct better for coding?

GPT-5.1-Codex scores higher on coding benchmarks: 41.9 versus 32.9 in the Noometry coding category.

How many benchmarks do GPT-5.1-Codex and Phi 3 Medium 4k Instruct share?

0 benchmarks have published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Phi 3 Medium 4k Instruct has 17.

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