The Known Good Updated 25 Jul 2026
OpenAI: GPT-5.1 vs Z.ai: GLM 5 ·OpenAI vs Z.ai

OpenAI: GPT-5.1 vs Z.ai: GLM 5 — head-to-head comparison

OpenAI: GPT-5.1 profile Z.ai: GLM 5 profile All comparisons
OpenAI: GPT-5.1 — OpenAI
Quality
#20 of 61
74based on 6 of 6 evaluations
Known Good Index
Speed
#119 of 316
61.9
Output tokens per second
Price
#261 of 340
$3.44
Blended per 1M tokens
In $1.25 · Out $10.00
Cache hit price
#105 of 206
$0.12
per 1M tokens (−90%)
Context
#101 of 345
400k
tokens (~600 pages)
Z.ai: GLM 5 — Z.ai
Quality
#19 of 61
77based on 4 of 6 evaluations
Known Good Index
Speed
#214 of 316
37.3
Output tokens per second
Price
#217 of 340
$1.35
Blended per 1M tokens
In $0.95 · Out $2.55
Cache hit price
#138 of 206
$0.20
per 1M tokens (−79%)
Context
#189 of 345
205k
tokens (~300 pages)
Summary

On the Known Good Index, OpenAI: GPT-5.1 scores 74 and Z.ai: GLM 5 scores 77 — a 3-point lead for Z.ai: GLM 5. They share 4 published evaluations, with OpenAI: GPT-5.1 ahead on 1 and Z.ai: GLM 5 ahead on 3.

Blended pricing is $3.44 per 1M tokens for OpenAI: GPT-5.1 and $1.35 for Z.ai: GLM 5 — Z.ai: GLM 5 is about 2.5× cheaper.

Throughput is 62 tokens per second for OpenAI: GPT-5.1 and 37 for Z.ai: GLM 5, with time to first token at 1.3s and 2.5s. OpenAI: GPT-5.1 accepts 400k tokens of context against 205k.

OpenAI: GPT-5.1 is proprietary; Z.ai: GLM 5 is open weights under Open weights (unrestricted). 16 tracked hosts serve one or both.

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

At a glance
MetricOpenAI: GPT-5.1Z.ai: GLM 5
Known Good Index 74 based on 6 of 6 evaluations 77 based on 4 of 6 evaluations
Blended $/1M $3.44 $1.35
Output tok/s 62 37
Context window 400k 205k
Providers 2 14
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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-5.1Z.ai: GLM 5
Known Good Index 74 77
Coding Index 68 67
Mathematics Index 89 80
Science Index 91 92
Reasoning Index 80
Agentic Index 61 67
Openness Index 5 60
The Known Good

Quality Breakdown

Every evaluation both models report a published score for

Evaluations both models report

Bar = OpenAI: GPT-5.1 · marker = Z.ai: GLM 5 · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond88 / 88
MATH / AIME89 / 80
SWE-bench Verified68 / 72
Terminal-Bench48 / 52

Right-hand figures read OpenAI: GPT-5.1 / Z.ai: GLM 5. OpenAI: GPT-5.1 leads on 1 of 4, Z.ai: GLM 5 on 3.

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-5.1Z.ai: GLM 5
Text Arena 1,422 1,445
Text Arena (style controlled) 1,439 1,457
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-5.1Z.ai: GLM 5
Input $/1M $1.25 $0.95
Output $/1M $10.00 $2.55
Blended $/1M $3.44 $1.35
Cache read $/1M $0.125 $0.200
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-5.1Z.ai: GLM 5
Context window 400k 205k
Max output tokens 128k 131k
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-5.1Z.ai: GLM 5
Output tokens/s 62 37
Time to first token 1.3s 2.5s
The Known Good

Providers

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

16 hosts
Full provider benchmarks →
Provider OpenAI: GPT-5.1 blendedOpenAI: GPT-5.1 tok/s Z.ai: GLM 5 blendedZ.ai: GLM 5 tok/s
OpenAI · first party $1.72 82
Azure · first party $3.44 58
Amazon Bedrock · first party $1.55 109
GMICloud $0.93 69
Chutes $1.35 48
Baidu · first party $1.08 43
Parasail $1.55 42
Phala $1.77 38
Novita $1.55 36
StreamLake $0.93 35
Z.AI · first party $1.55 33
Venice $1.55 32
DeepInfra $0.97 29
SiliconFlow $1.35 29
AtlasCloud $1.50 26
DigitalOcean $1.16 8

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 →