The Known Good Updated 25 Jul 2026
OpenAI: gpt-oss-120b vs Z.ai: GLM 5.1 ·OpenAI vs Z.ai

OpenAI: gpt-oss-120b vs Z.ai: GLM 5.1 — head-to-head comparison

OpenAI: gpt-oss-120b profile Z.ai: GLM 5.1 profile All comparisons
OpenAI: gpt-oss-120b — OpenAI
Quality
#33 of 61
61based on 3 of 6 evaluations
Known Good Index
Speed
#10 of 316
172.2
Output tokens per second
Price
#33 of 340
$0.07
Blended per 1M tokens
In $0.04 · Out $0.17
Cache hit price
#25 of 206
$0.015
per 1M tokens (−59%)
Context
#238 of 345
131k
tokens (~200 pages)
Z.ai: GLM 5.1 — Z.ai
Quality
#12 of 61
88based on 3 of 6 evaluations
Known Good Index
Speed
#154 of 316
53.4
Output tokens per second
Price
#221 of 340
$1.48
Blended per 1M tokens
In $0.97 · Out $3.04
Cache hit price
#136 of 206
$0.18
per 1M tokens (−81%)
Context
#195 of 345
205k
tokens (~300 pages)
Summary

On the Known Good Index, OpenAI: gpt-oss-120b scores 61 and Z.ai: GLM 5.1 scores 88 — a 27-point lead for Z.ai: GLM 5.1. They share 2 published evaluations, with OpenAI: gpt-oss-120b ahead on 0 and Z.ai: GLM 5.1 ahead on 2.

Blended pricing is $0.07 per 1M tokens for OpenAI: gpt-oss-120b and $1.48 for Z.ai: GLM 5.1 — OpenAI: gpt-oss-120b is about 21.1× cheaper.

Throughput is 172 tokens per second for OpenAI: gpt-oss-120b and 53 for Z.ai: GLM 5.1, with time to first token at 0.7s and 1.9s. OpenAI: gpt-oss-120b accepts 131k tokens of context against 205k.

OpenAI: gpt-oss-120b is open weights under Open weights (unrestricted); Z.ai: GLM 5.1 is proprietary. 28 tracked hosts serve one or both, and 8 serve both.

Generated from tracked data on 25 Jul 2026 · how these comparisons are computed →

At a glance
MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Known Good Index 61 based on 3 of 6 evaluations 88 based on 3 of 6 evaluations
Blended $/1M $0.07 $1.48
Output tok/s 172 53
Context window 131k 205k
Providers 17 19
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Quality

Known Good Index and the capability indices, side by side

IndicesComponents
Index scores

Each index is min-max normalised across tracked models and scaled 0–100 from published evaluations. We do not run these evaluations.

MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Known Good Index 61 88
Mathematics Index 89 92
Science Index 77 89
Agentic Index 18 82
Openness Index 60 5
The Known Good

Quality Breakdown

Every evaluation both models report a published score for

Evaluations both models report

Bar = OpenAI: gpt-oss-120b · marker = Z.ai: GLM 5.1 · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond76 / 85
MATH / AIME89 / 92

Right-hand figures read OpenAI: gpt-oss-120b / Z.ai: GLM 5.1. OpenAI: gpt-oss-120b leads on 0 of 2, Z.ai: GLM 5.1 on 2.

The Known Good

Arena Elo

Human preference rating from blind pairwise votes

Arena ratings

Elo from blind pairwise votes, ingested from Arena. Higher is better.

MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Text Arena 1,366 1,465
Text Arena (style controlled) 1,352 1,470
The Known Good

Price & Cost

Published API pricing by token type

Per token typeCache discount
Published pricing

USD per 1M tokens. Blended is a 3:1 input:output mix. Live from OpenRouter, cross-checked against models.dev. Lower is better.

MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Input $/1M $0.04 $0.97
Output $/1M $0.17 $3.04
Blended $/1M $0.07 $1.48
Cache read $/1M $0.015 $0.179
The Known Good
We publish blended price rather than cost-per-task. Cost-per-task requires token counts from an evaluation suite we do not run. Blended price is computed from published rates and is fully reproducible — see the pricing methodology.

Context Window

Maximum input accepted and maximum output emitted

Context and output limits

Provider-declared limits, from metadata via models.dev and OpenRouter. Higher is better.

MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Context window 131k 205k
Max output tokens 131k 128k
The Known Good

Speed & Latency

Median throughput and time to first token across hosting providers

Output speedTime to first token
Throughput and latency

Medians across all tracked providers, derived from OpenRouter endpoint telemetry.

MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Output tokens/s 172 53
Time to first token 0.7s 1.9s
The Known Good

Providers

Which hosts serve each model, and at what price and speed

28 hosts · 8 serve both
Full provider benchmarks →
Provider OpenAI: gpt-oss-120b blendedOpenAI: gpt-oss-120b tok/s Z.ai: GLM 5.1 blendedZ.ai: GLM 5.1 tok/s
Cerebras $0.45 495
Groq $0.26 411
SambaNova $0.34 306
BaseTen $0.20 285
Nebius $0.26 281 $2.15 26
DeepInfra $0.07 246 $1.66 66
Parasail $0.26 207 $2.15 71
Mara $0.30 181
Amazon Bedrock · first party $0.26 166
Together $0.26 111
Google · first party $0.16 85
Phala $0.26 82 $1.96
DigitalOcean $0.17 62 $1.81 21
Novita $0.10 42 $2.13 52
CoreWeave $0.07 41 $2.15 120
Mancer 2 $0.17 41
SiliconFlow $0.15 26 $1.83 62
Friendli $2.15 109
Crusoe $2.00 91
Fireworks $2.15 90
Venice $2.37 80
GMICloud $1.50 77
Baidu · first party $1.50 51
Wafer $1.55 50
Chutes $1.50 48
AtlasCloud $1.94 42
Z.AI · first party $2.15 37
StreamLake $1.48 25

Per-host pricing and telemetry from OpenRouter. A dash means that host does not serve that model.

The Known Good
Sources for this page
Pricing & providers — OpenRouter Metadata — models.dev Benchmarks — Epoch AI (CC-BY 4.0)Elo — Arena Full attribution →