The Known Good Updated 4 Sep 2026 Subscribe
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
#44 of 65
62based on 3 of 7 evaluations
Known Good Index
Speed
#9 of 338
166.7
Output tokens per second
Price
#19 of 442
$0.07
Blended per 1M tokens
In $0.04 · Out $0.17
Cache hit price
unranked
per 1M tokens
Context
#363 of 476
131k
tokens (~200 pages)
Z.ai: GLM 5.1 — Z.ai
Quality
#11 of 65
90based on 3 of 7 evaluations
Known Good Index
Speed
#222 of 338
38.7
Output tokens per second
Price
#268 of 442
$1.48
Blended per 1M tokens
In $0.97 · Out $3.04
Cache hit price
#219 of 324
$0.18
per 1M tokens (−81%)
Context
#290 of 476
205k
tokens (~300 pages)
Summary

On the Known Good Index, OpenAI: gpt-oss-120b scores 62 and Z.ai: GLM 5.1 scores 90 — a 28-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 167 tokens per second for OpenAI: gpt-oss-120b and 39 for Z.ai: GLM 5.1, with time to first token at 0.6s and 2.0s. 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 open weights under Open weights (unrestricted). 30 tracked hosts serve one or both, and 8 serve both.

Generated from tracked data on 4 Sep 2026 · how these comparisons are computed →

At a glance
MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Known Good Index 62 based on 3 of 7 evaluations 90 based on 3 of 7 evaluations
Blended $/1M $0.07 $1.48
Output tok/s 167 39
Context window 131k 205k
Providers 18 20
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Quality

Known Good Index and the capability indices, side by side

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 62 90
Openness Index 60 60
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 / 90
Mock AIME 2024–2589 / 93

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 1,463
Text Arena (style controlled) 1,352 1,466
The Known Good

Price & Cost

Published API pricing by token type

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 $0.179
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 118k 128k
The Known Good

Speed & Latency

Mean throughput and time to first token across hosting providers, over successful measurements from the last 48 hours

Throughput and latency

Means across all tracked providers over successful measurements from the last 48 hours, derived from OpenRouter endpoint telemetry.

MetricOpenAI: gpt-oss-120bZ.ai: GLM 5.1
Output tokens/s 167 39
Time to first token 0.6s 2.0s
The Known Good

Providers

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

30 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 $0.45 788
Groq $0.26 344
Amazon Bedrock · first party $0.26 330
SambaNova $0.34 319
Nebius $0.26 247 $2.15 27
BaseTen $0.20 187
Mara $0.30 150
Google · first party $0.16 142
DeepInfra $0.07 130 $1.66 31
Parasail $0.26 107 $2.15
Novita $0.10 102 $2.13 36
Mancer 2 $0.17 95
Phala $0.26 85 $1.96 32
Together $0.26 60
CoreWeave $0.07 57 $2.15 79
AkashML $0.07 43
DigitalOcean $0.14 27 $2.05 12
SiliconFlow $0.15 18 $1.83 27
Crusoe $2.00 92
Friendli $2.15 69
Wafer $1.55 60
Baidu · first party $2.15 58
GMICloud $1.40 56
Alibaba · first party $2.04 55
AtlasCloud $1.94 47
Chutes $1.50 38
Venice $2.37 34
StreamLake $1.48 31
Z.AI · first party $2.15 17
Fireworks $2.15

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 →