Model comparison

gpt-oss-120b vs Grok 4.20 (Non-Reasoning)

Grok 4.20 (Non-Reasoning) is the stronger model overall, scoring 48.5 to 36.0 on the Noometry Index. gpt-oss-120b costs 22× less per token, which makes it the better buy when Grok 4.20 (Non-Reasoning)'s lead doesn't matter for your workload.

Last verified October 10, 2026. 29 shared benchmarks.

gpt-oss-120b OpenAI

36.0

Rank #210 Confirmed

Grok 4.20 (Non-Reasoning) xAI

48.5

Rank #48 Confirmed

Summary

They share 29 benchmarks with published results for both. gpt-oss-120b scores higher in 1 category and Grok 4.20 (Non-Reasoning) in 8 categories; 9 gaps are clear of the uncertainty.
The widest gap is in reasoning, where Grok 4.20 (Non-Reasoning) leads 52.2 to 19.5.
The biggest single-benchmark swing is Terminal-Bench: 18.7% for gpt-oss-120b and 57.3% for Grok 4.20 (Non-Reasoning).
gpt-oss-120b is cheaper at $0.037 / $0.17 per million input/output tokens, against $1.25 / $2.50 for Grok 4.20 (Non-Reasoning).
Grok 4.20 (Non-Reasoning) accepts more context: 1M tokens versus 131K.
gpt-oss-120b has downloadable open weights; the other is API-only.

Side by side

gpt-oss-120b and Grok 4.20 (Non-Reasoning) specifications
	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
Provider	OpenAI	xAI
Noometry Index	36.0	48.5
Released	2025-08-05	2026-02-17
Weights	Open	Proprietary
Context window	131K	1M
Max output	41K	30K
Input $ / M tokens	$0.037	$1.25
Output $ / M tokens	$0.17	$2.50
Results tracked	48	46

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Category by category

Coding Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 33.2 (#251), Grok 4.20 (Non-Reasoning): 41.8 (#104)

Coding benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
WeirdML	48.2%	52.3%
LMArena Coding	1380	1458
ALE-Bench	575.62	1,150
SWE-bench Verified (bash only)	26%	—
Aider Polyglot	41.8%	—
LMArena WebDev	—	1374
SciCode	36%	—
AlgoTune	1.41	—

Agentic & Tool Use Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 12.1 (#145), Grok 4.20 (Non-Reasoning): 34.3 (#43)

Agentic & Tool Use benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
Terminal-Bench	18.7%	57.3%
Vending-Bench 2	-21.53	4,663
APEX-Agents	4.4%	—
τ²-bench Banking	—	18%
LMArena Search	—	1189
METR Time Horizons	56.6%	—

Reasoning Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 19.5 (#236), Grok 4.20 (Non-Reasoning): 52.2 (#30)

Reasoning benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
Kagi LLM Benchmark	58.6%	75%
Chess Puzzles	20%	24%
LMArena Hard Prompts	1364	1451
DTBench	76.3%	90.1%
LMCA	22.1%	38.7%
Epoch Capabilities Index	139.94	152.01
ARC-AGI-2	—	65.1%
SimpleBench	22.1%	—
NYT Connections (extended)	—	85.4%
ARC-AGI-1	—	89.5%
CritPt	1.1%	—
Thematic Generalization	—	63.8%
Mystery Game Puzzles	2%	—
Surface Evolver Bench	25%	—
ForecastBench	—	61.4

Math gpt-oss-120b leads

gpt-oss-120b: 50.6 (#43), Grok 4.20 (Non-Reasoning): 48.0 (#54)

Math benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
OTIS Mock AIME 2024-2025	88.9%	92.2%
LMArena Math	1388	1455
FrontierMath (Tiers 1-3)	—	44.9%
FrontierMath Tier 4	—	17.1%
ProofBench	—	14%
Omni-MATH	68.8%	—

Knowledge Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 42.3 (#89), Grok 4.20 (Non-Reasoning): 52.8 (#54)

Knowledge benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
GPQA Diamond	75.8%	89.3%
LMArena Expert	1356	1440
SimpleQA Verified	—	30.2%
MMLU-Pro	79.5%	—
Confabulations	15.7%	—
Vectara Hallucination Rate	14.2%	—
GPQA (HELM)	68.4%	—

Multimodal Not comparable

gpt-oss-120b: —, Grok 4.20 (Non-Reasoning): 33.2 (#88)

Multimodal benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
LMArena Vision	—	1263
Blueprint-Bench 2	—	0%
LMArena Document	—	1416

Multilingual Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 48.2 (#142), Grok 4.20 (Non-Reasoning): 54.7 (#38)

Multilingual benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
LMArena Non-English	1350	1440
LMArena Chinese	1384	1481
LMArena French	1370	1477
LMArena German	1355	1463
LMArena Japanese	1332	1450
LMArena Korean	1283	1417
LMArena Russian	1343	1457
LMArena Spanish	1388	1442

Instruction Following Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 69.5 (#168), Grok 4.20 (Non-Reasoning): 75.0 (#79)

Instruction Following benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
LMArena Instruction Following	1318	1420
IFEval	83.6%	—

Long Context Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 31.4 (#273), Grok 4.20 (Non-Reasoning): 45.4 (#33)

Long Context benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
LMArena Longer Query	1319	1436
Fiction.LiveBench	44.4%	—
CL-bench	—	22.2%
CL-bench Life	—	11.9%

Writing & Preference Grok 4.20 (Non-Reasoning) leads

gpt-oss-120b: 46.7 (#213), Grok 4.20 (Non-Reasoning): 65.9 (#42)

Writing & Preference benchmarks
Benchmark	gpt-oss-120b	Grok 4.20 (Non-Reasoning)
LMArena Text	1366	1451
LMArena Creative Writing	1274	1439
EQ-Bench Creative Writing	961	1574
LMArena Multi-Turn	1340	1456
Short-Story Creative Writing	77.1%	—
WildBench	84.5%	—

Frequently asked questions

Is gpt-oss-120b better than Grok 4.20 (Non-Reasoning)?

Which is cheaper, gpt-oss-120b or Grok 4.20 (Non-Reasoning)?

gpt-oss-120b is cheaper. It lists at $0.037 per million input tokens and $0.17 per million output tokens; Grok 4.20 (Non-Reasoning) lists at $1.25 and $2.50.

Is gpt-oss-120b or Grok 4.20 (Non-Reasoning) better for coding?

Grok 4.20 (Non-Reasoning) scores higher on coding benchmarks: 41.8 versus 33.2 in the Noometry coding category.

Which has the bigger context window?

Grok 4.20 (Non-Reasoning) does, with 1M tokens against 131K.

How many benchmarks do gpt-oss-120b and Grok 4.20 (Non-Reasoning) share?

29 benchmarks have published results for both models. gpt-oss-120b has 48 scored results on Noometry and Grok 4.20 (Non-Reasoning) has 46.