The Known Good Updated 22 Oct 2026 Subscribe
OpenAI: GPT-5.5 vs Z.ai: GLM 5.2 ·OpenAI vs Z.ai

OpenAI: GPT-5.5 vs Z.ai: GLM 5.2 — head-to-head comparison

OpenAI: GPT-5.5 profile Z.ai: GLM 5.2 profile All comparisons
OpenAI: GPT-5.5 — OpenAI
Quality
#5 of 65
93based on 3 of 7 evaluations
Known Good Index
Speed
#114 of 353
87.2
Output tokens per second
Price
#493 of 524
$11.25
Blended per 1M tokens
In $5.00 · Out $30.00
Cache hit price
#376 of 410
$0.50
per 1M tokens (−90%)
Context
#40 of 573
1.05M
tokens (~1,600 pages)
Z.ai: GLM 5.2 — Z.ai
Quality
#8 of 65
91based on 3 of 7 evaluations
Known Good Index
Speed
#87 of 353
101.2
Output tokens per second
Price
#347 of 524
$1.78
Blended per 1M tokens
In $0.03 · Out $7.00
Cache hit price
#134 of 410
$0.033
per 1M tokens (−3%)
Context
#110 of 573
1.05M
tokens (~1,600 pages)
Summary

On the Known Good Index, OpenAI: GPT-5.5 scores 93 and Z.ai: GLM 5.2 scores 91 — a 2-point lead for OpenAI: GPT-5.5. They share 2 published evaluations, with OpenAI: GPT-5.5 ahead on 0 and Z.ai: GLM 5.2 ahead on 2.

Blended pricing is $11.25 per 1M tokens for OpenAI: GPT-5.5 and $1.78 for Z.ai: GLM 5.2 — Z.ai: GLM 5.2 is about 6.3× cheaper.

Throughput is 87 tokens per second for OpenAI: GPT-5.5 and 101 for Z.ai: GLM 5.2, with time to first token at 3.4s and 1.3s. OpenAI: GPT-5.5 accepts 1.05M tokens of context against 1.05M.

OpenAI: GPT-5.5 is proprietary; Z.ai: GLM 5.2 is open weights under Open weights (unrestricted). 40 tracked hosts serve one or both.

Generated from tracked data on 22 Oct 2026 · how these comparisons are computed →

At a glance
MetricOpenAI: GPT-5.5Z.ai: GLM 5.2
Known Good Index 93 based on 3 of 7 evaluations 91 based on 3 of 7 evaluations
Blended $/1M $11.25 $1.78
Output tok/s 87 101
Context window 1.05M 1.05M
Providers 3 37
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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-5.5Z.ai: GLM 5.2
Known Good Index 93 91
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-5.5 · marker = Z.ai: GLM 5.2 · scores ingested from Epoch AI (CC-BY 4.0)

GPQA Diamond91 / 92
Mock AIME 2024–2584 / 86

Right-hand figures read OpenAI: GPT-5.5 / Z.ai: GLM 5.2. OpenAI: GPT-5.5 leads on 0 of 2, Z.ai: GLM 5.2 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-5.5Z.ai: GLM 5.2
Text Arena 1,467 1,470
Text Arena (style controlled) 1,477 1,476
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-5.5Z.ai: GLM 5.2
Input $/1M $5.00 $0.03
Output $/1M $30.00 $7.00
Blended $/1M $11.25 $1.78
Cache read $/1M $0.500 $0.033
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-5.5Z.ai: GLM 5.2
Context window 1.05M 1.05M
Max output tokens 128k 944k
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-5.5Z.ai: GLM 5.2
Output tokens/s 87 101
Time to first token 3.4s 1.3s
The Known Good

Providers

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

40 hosts
Full provider benchmarks →
Provider OpenAI: GPT-5.5 blendedOpenAI: GPT-5.5 tok/s Z.ai: GLM 5.2 blendedZ.ai: GLM 5.2 tok/s
Amazon Bedrock · first party $12.38 94 — —
Azure · first party $11.25 83 — —
OpenAI · first party $5.62 75 — —
Decart — — $2.90 517
CoreWeave — — $1.07 202
Parasail — — $2.15 169
BaseTen — — $2.15 150
Reka · first party — — $1.60 149
Wafer — — $1.78 138
Together — — $2.15 135
Mistral · first party — — $2.15 120
ModelRun — — $3.35 108
Relace — — $1.30 104
Ambient — — $0.95 102
Inceptron — — $0.71 102
Crusoe — — $2.15 100
Venice — — $2.15 90
Nebius — — $2.15 89
InferenceNet — — $2.08 87
Friendli — — $2.15 82
Alibaba · first party — — $1.48 79
Makora — — $1.14 78
Baidu · first party — — $0.29 74
DigitalOcean — — $1.07 74
Cloudflare — — $2.14 68
SiliconFlow — — $1.07 62
DeepInfra — — $0.70 59
StreamLake — — $0.86 58
Io Net — — $1.33 56
AtlasCloud — — $1.44 47
Z.AI · first party — — $2.15 46
Novita — — $1.00 42
Morph — — $1.30 41
GMICloud — — $2.15 39
Sail Research — — $1.16 37
Ionstream — — $2.15 30
AkashML — — $1.18 27
Phala — — $1.70 13
Chutes — — $1.93 4
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 →