Noometry

Model comparison

GPT-5.5 Instant vs gpt-oss-120b

GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 36.3 on the Noometry Index.

Last verified . 23 shared benchmarks.

GPT-5.5 Instant OpenAI

42.7

Rank #110 Confirmed

gpt-oss-120b OpenAI

36.3

Rank #217 Confirmed

Summary

  • They share 23 benchmarks with published results for both. GPT-5.5 Instant scores higher in 7 categories and gpt-oss-120b in 1 category; 8 gaps are clear of the uncertainty.
  • The widest gap is in math, where gpt-oss-120b leads 52.5 to 26.5.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 68.1% for GPT-5.5 Instant and 88.9% for gpt-oss-120b.
  • gpt-oss-120b has downloadable open weights; the other is API-only.

Side by side

GPT-5.5 Instantgpt-oss-120b
ProviderOpenAIOpenAI
Noometry Index42.736.3
Released2026-05-052025-08-05
WeightsProprietaryOpen
Context window—131K
Max output—41K
Input $ / M tokens—$0.037
Output $ / M tokens—$0.17
Results tracked2748

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Category by category

Coding GPT-5.5 Instant leads

GPT-5.5 Instant: 44.3 (#74), gpt-oss-120b: 33.5 (#256)

BenchmarkGPT-5.5 Instantgpt-oss-120b
SciCode48.6%36%
LMArena Coding14331380
SWE-bench Verified (bash only)—26%
Aider Polyglot—41.8%
WeirdML—48.2%
ALE-Bench—575.62
AlgoTune—1.41

Agentic & Tool Use Not comparable

GPT-5.5 Instant: —, gpt-oss-120b: 12.2 (#153)

BenchmarkGPT-5.5 Instantgpt-oss-120b
Terminal-Bench—18.7%
APEX-Agents—4.4%
METR Time Horizons—56.6%
Vending-Bench 2—-21.53

Reasoning GPT-5.5 Instant leads

GPT-5.5 Instant: 24.9 (#155), gpt-oss-120b: 20.0 (#245)

BenchmarkGPT-5.5 Instantgpt-oss-120b
CritPt0%1.1%
Chess Puzzles12%20%
LMArena Hard Prompts14261364
Epoch Capabilities Index142.52139.93
SimpleBench—22.1%
Kagi LLM Benchmark—58.6%
Mystery Game Puzzles—2%
DTBench—76.3%
LMCA—22.1%
Surface Evolver Bench—25%

Math gpt-oss-120b leads

GPT-5.5 Instant: 26.5 (#259), gpt-oss-120b: 52.5 (#50)

BenchmarkGPT-5.5 Instantgpt-oss-120b
OTIS Mock AIME 2024-202568.1%88.9%
LMArena Math14201389
FrontierMath (Tiers 1-3)26.3%—
FrontierMath Tier 42.4%—
Omni-MATH—68.8%

Knowledge GPT-5.5 Instant leads

GPT-5.5 Instant: 48.9 (#74), gpt-oss-120b: 42.4 (#96)

BenchmarkGPT-5.5 Instantgpt-oss-120b
GPQA Diamond82.5%75.8%
LMArena Expert14091356
MMLU-Pro—79.5%
Confabulations—15.7%
Vectara Hallucination Rate—14.2%
GPQA (HELM)—68.4%

Multimodal Not comparable

GPT-5.5 Instant: 40.0 (#52), gpt-oss-120b: —

BenchmarkGPT-5.5 Instantgpt-oss-120b
LMArena Vision1250—
LMArena Document1403—

Multilingual GPT-5.5 Instant leads

GPT-5.5 Instant: 52.8 (#80), gpt-oss-120b: 48.0 (#147)

BenchmarkGPT-5.5 Instantgpt-oss-120b
LMArena Non-English14171351
LMArena Chinese14561385
LMArena French14281369
LMArena German14111353
LMArena Japanese14081331
LMArena Korean13921282
LMArena Russian14311343
LMArena Spanish14291389

Instruction Following GPT-5.5 Instant leads

GPT-5.5 Instant: 74.2 (#100), gpt-oss-120b: 69.3 (#173)

BenchmarkGPT-5.5 Instantgpt-oss-120b
LMArena Instruction Following14061318
IFEval—83.6%

Long Context GPT-5.5 Instant leads

GPT-5.5 Instant: 43.4 (#96), gpt-oss-120b: 31.4 (#278)

BenchmarkGPT-5.5 Instantgpt-oss-120b
LMArena Longer Query14221319
Fiction.LiveBench—44.4%

Writing & Preference GPT-5.5 Instant leads

GPT-5.5 Instant: 61.8 (#85), gpt-oss-120b: 46.5 (#217)

BenchmarkGPT-5.5 Instantgpt-oss-120b
LMArena Text14191365
LMArena Creative Writing14191275
LMArena Multi-Turn14331340
Short-Story Creative Writing—77.1%
EQ-Bench Creative Writing—961
WildBench—84.5%

Frequently asked questions

Is GPT-5.5 Instant better than gpt-oss-120b?

GPT-5.5 Instant is the stronger model overall, scoring 42.7 to 36.3 on the Noometry Index.

Is GPT-5.5 Instant or gpt-oss-120b better for coding?

GPT-5.5 Instant scores higher on coding benchmarks: 44.3 versus 33.5 in the Noometry coding category.

How many benchmarks do GPT-5.5 Instant and gpt-oss-120b share?

23 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and gpt-oss-120b has 48.

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