Model comparison

GLM-4.5 vs gpt-oss-20b

GLM-4.5 is the stronger model overall, scoring 41.4 to 32.1 on the Noometry Index. gpt-oss-20b costs 28× less per token, which makes it the better buy when GLM-4.5's lead doesn't matter for your workload.

Last verified October 10, 2026. 20 shared benchmarks.

GLM-4.5 Z.ai (Zhipu)

41.4

Rank #125 Confirmed

gpt-oss-20b OpenAI

32.1

Rank #249 Confirmed

Summary

They share 20 benchmarks with published results for both. GLM-4.5 scores higher in 7 categories and gpt-oss-20b in 1 category; 6 gaps are clear of the uncertainty.
The widest gap is in writing & preference, where GLM-4.5 leads 57.7 to 35.8.
gpt-oss-20b is cheaper at $0.018 / $0.09 per million input/output tokens, against $0.60 / $2.20 for GLM-4.5.

Side by side

GLM-4.5 and gpt-oss-20b specifications
	GLM-4.5	gpt-oss-20b
Provider	Z.ai (Zhipu)	OpenAI
Noometry Index	41.4	32.1
Released	2025-07-27	2025-08-05
Weights	Open	Open
Context window	131K	131K
Max output	98K	16K
Input $ / M tokens	$0.60	$0.018
Output $ / M tokens	$2.20	$0.09
Results tracked	27	34

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Category by category

Coding GLM-4.5 leads

GLM-4.5: 41.1 (#121), gpt-oss-20b: 37.1 (#185)

Coding benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
WeirdML	40.6%	40.9%
LMArena Coding	1434	1307
ALE-Bench	344.82	566.05
SWE-bench Verified (bash only)	54.2%	—
SciCode	—	34.4%
AlgoTune	1.52	—

Agentic & Tool Use Not comparable

GLM-4.5: —, gpt-oss-20b: 9.2 (#146)

Agentic & Tool Use benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
Terminal-Bench	—	3.4%

Reasoning GLM-4.5 leads

GLM-4.5: 27.7 (#99), gpt-oss-20b: 18.8 (#251)

Reasoning benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
Kagi LLM Benchmark	57.9%	53.2%
LMArena Hard Prompts	1430	1274
CritPt	—	1.4%
Chess Puzzles	—	4%
DTBench	—	68%
LMCA	—	14.5%
Epoch Capabilities Index	—	137.81

Math gpt-oss-20b leads

GLM-4.5: 36.3 (#119), gpt-oss-20b: 37.6 (#93)

Math benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
LMArena Math	1427	1317
OTIS Mock AIME 2024-2025	—	65.3%
Omni-MATH	—	56.5%

Knowledge Too close to call

GLM-4.5: 35.5 (#172), gpt-oss-20b: 34.6 (#186)

Knowledge benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
LMArena Expert	1433	1258
GPQA Diamond	—	60.8%
Humanity's Last Exam	8.3%	—
MMLU-Pro	—	74%
Confabulations	11.3%	—
GPQA (HELM)	—	59.4%

Multilingual GLM-4.5 leads

GLM-4.5: 53.0 (#74), gpt-oss-20b: 42.4 (#192)

Multilingual benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
LMArena Non-English	1417	1269
LMArena Chinese	1465	1311
LMArena German	1406	1249
LMArena Japanese	1416	1245
LMArena Korean	1382	1239
LMArena Russian	1414	1279
LMArena Spanish	1454	1267
LMArena French	1423	—

Instruction Following GLM-4.5 leads

GLM-4.5: 74.3 (#100), gpt-oss-20b: 62.0 (#235)

Instruction Following benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
LMArena Instruction Following	1405	1236
IFEval	—	73.2%

Long Context Too close to call

GLM-4.5: 38.2 (#196), gpt-oss-20b: 37.9 (#203)

Long Context benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
LMArena Longer Query	1413	1251
Fiction.LiveBench	58.3%	—

Writing & Preference GLM-4.5 leads

GLM-4.5: 57.7 (#121), gpt-oss-20b: 35.8 (#260)

Writing & Preference benchmarks
Benchmark	GLM-4.5	gpt-oss-20b
LMArena Text	1430	1288
LMArena Creative Writing	1395	1201
EQ-Bench Creative Writing	1343	666
LMArena Multi-Turn	1415	1268
Short-Story Creative Writing	73.4%	—
WildBench	—	73.7%

Frequently asked questions

Is GLM-4.5 better than gpt-oss-20b?

Which is cheaper, GLM-4.5 or gpt-oss-20b?

gpt-oss-20b is cheaper. It lists at $0.018 per million input tokens and $0.09 per million output tokens; GLM-4.5 lists at $0.60 and $2.20.

Is GLM-4.5 or gpt-oss-20b better for coding?

GLM-4.5 scores higher on coding benchmarks: 41.1 versus 37.1 in the Noometry coding category.

Which has the bigger context window?

Both accept 131K tokens.

How many benchmarks do GLM-4.5 and gpt-oss-20b share?

20 benchmarks have published results for both models. GLM-4.5 has 27 scored results on Noometry and gpt-oss-20b has 34.