The Known Good Updated 25 Jul 2026
OpenAI: o3 vs Z.ai: GLM 5.1 ·OpenAI vs Z.ai

OpenAI: o3 vs Z.ai: GLM 5.1 — head-to-head comparison

OpenAI: o3 profile Z.ai: GLM 5.1 profile All comparisons
OpenAI: o3 — OpenAI
Quality
#28 of 61
67based on 4 of 6 evaluations
Known Good Index
Speed
#70 of 316
88.5
Output tokens per second
Price
#269 of 340
$3.50
Blended per 1M tokens
In $2.00 · Out $8.00
Cache hit price
#175 of 206
$0.50
per 1M tokens (−75%)
Context
#203 of 345
200k
tokens (~300 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: o3 scores 67 and Z.ai: GLM 5.1 scores 88 — a 21-point lead for Z.ai: GLM 5.1. They share 3 published evaluations, with OpenAI: o3 ahead on 0 and Z.ai: GLM 5.1 ahead on 3.

Blended pricing is $3.50 per 1M tokens for OpenAI: o3 and $1.48 for Z.ai: GLM 5.1 — Z.ai: GLM 5.1 is about 2.4× cheaper.

Throughput is 88 tokens per second for OpenAI: o3 and 53 for Z.ai: GLM 5.1, with time to first token at 2.7s and 1.9s. OpenAI: o3 accepts 200k tokens of context against 205k.

OpenAI: o3 is proprietary; Z.ai: GLM 5.1 is proprietary. 20 tracked hosts serve one or both.

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

At a glance
MetricOpenAI: o3Z.ai: GLM 5.1
Known Good Index 67 based on 4 of 6 evaluations 88 based on 3 of 6 evaluations
Blended $/1M $3.50 $1.48
Output tok/s 88 53
Context window 200k 205k
Providers 1 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: o3Z.ai: GLM 5.1
Known Good Index 67 88
Mathematics Index 92 92
Science Index 84 89
Reasoning Index 62
Agentic Index 60 82
Openness Index 5 5
The Known Good

Quality Breakdown

Every evaluation both models report a published score for

Evaluations both models report

Bar = OpenAI: o3 · marker = Z.ai: GLM 5.1 · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond82 / 85
MATH / AIME84 / 92
SWE-bench Verified62 / 74

Right-hand figures read OpenAI: o3 / Z.ai: GLM 5.1. OpenAI: o3 leads on 0 of 3, Z.ai: GLM 5.1 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: o3Z.ai: GLM 5.1
Text Arena 1,465
Text Arena (style controlled) 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: o3Z.ai: GLM 5.1
Input $/1M $2.00 $0.97
Output $/1M $8.00 $3.04
Blended $/1M $3.50 $1.48
Cache read $/1M $0.500 $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: o3Z.ai: GLM 5.1
Context window 200k 205k
Max output tokens 100k 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: o3Z.ai: GLM 5.1
Output tokens/s 88 53
Time to first token 2.7s 1.9s
The Known Good

Providers

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

20 hosts
Full provider benchmarks →
Provider OpenAI: o3 blendedOpenAI: o3 tok/s Z.ai: GLM 5.1 blendedZ.ai: GLM 5.1 tok/s
OpenAI · first party $3.50 72
CoreWeave $2.15 120
Friendli $2.15 109
Crusoe $2.00 91
Fireworks $2.15 90
Venice $2.37 80
GMICloud $1.50 77
Parasail $2.15 71
DeepInfra $1.66 66
SiliconFlow $1.83 62
Novita $2.13 52
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
Nebius $2.15 26
StreamLake $1.48 25
DigitalOcean $1.81 21
Phala $1.96

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 →