Head-to-head comparison

GPT-5.5 vs. GLM-5.3-Flash

Compare published benchmark results from matching versions and cohorts, API pricing, and technical specifications. Any documented test setup differences remain visible.

shared result series: 18
distinct benchmarks: 18
latest retrieval: 2026-09-04

First modelSecond model

Specifications

General specifications

Release date, availability, context window, architecture, and published parameter counts at a glance. Undisclosed details remain marked as unavailable.

Specifications for GPT-5.5 and GLM-5.3-Flash
Attribute	GPT-5.5	GLM-5.3-Flash
Provider	OpenAI	Z.ai
Released	Apr 23, 2026	Aug 26, 2026
Availability	Active	Open Source
Model type	Proprietary	Open Weights
Parameters	Not published	320B, 18B active
Architecture	Not published	Mixture of Experts
Context window	1,050,000 tokens	1,000,000 tokens
Knowledge cutoff	December 1, 2025	Not published
Technical sources	Model	Model, Context

Pricing

API pricing compared

The table compares official standard API rates per 1M tokens, including published cache pricing. Batch, fast, priority, regional surcharges, tool calls, and cloud platform pricing are excluded.

API pricing for GPT-5.5 and GLM-5.3-Flash
Price type	GPT-5.5	GLM-5.3-Flash
API input	$5 ≤272K / $10 >272K	$0.07
API output	$30 ≤272K / $45 >272K	$0.25
Cache read	$0.5 ≤272K / $1 >272K	$0.01
Cache write (5 min.)	Not listed	Not listed
Cache write (1 hr.)	Not listed	Not listed
Price verified	07/30/2026 Source	08/29/2026 Source

GPT-5.5GLM-5.3-Flash

API inputUSD per 1M tokens, base tier

GPT-5.5$5

GLM-5.3-Flash$0.075

API outputUSD per 1M tokens, base tier

GPT-5.5$30

GLM-5.3-Flash$0.25

Cache readUSD per 1M tokens, base tier

GPT-5.5$0.5

GLM-5.3-Flash$0.015

Key to the marks:better valuebetter, but not conclusivetie

Pricing by provider

Direct developer pricing and provider endpoint tariffs routed through OpenRouter are listed separately. Prices are in USD per 1M tokens. Context-dependent direct tiers plus regional, Flex, Priority, and other OpenRouter tariffs remain individually identifiable.

Provider pricing for GPT-5.5 and GLM-5.3-Flash
Model	Provider	Purchase route and tariff	Input per 1M tokens	Output per 1M tokens	Source
GPT-5.5	OpenAI	Direct from developerUp to 272,000 context tokens	$5	$30	Source07/30/2026
	OpenAI	Direct from developerAbove 272,000 context tokens	$10	$45	Source07/30/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/us-east-1	$5.5	$33	Source09/08/2026
	Azure	Via OpenRouterazure	$5	$30	Source09/08/2026
	Azure	Via OpenRouterazure/eu	$5.5	$33	Source09/08/2026
	Azure	Via OpenRouterazure/us	$5.5	$33	Source09/08/2026
	OpenAI	Via OpenRouteropenai	$5	$30	Source09/08/2026
	OpenAI	Via OpenRouteropenai/fast	$12.5	$75	Source09/08/2026
	OpenAI	Via OpenRouteropenai/flex	Lowest listed price: $2.5	Lowest listed price: $15	Source09/08/2026
GLM-5.3-Flash	Z.ai	Direct from developerStandard API	$0.075	$0.25	Source08/29/2026
	BaseTen	Via OpenRouterbaseten/fp8	$0.15	$0.5	Source09/08/2026
	Cloudflare	Via OpenRoutercloudflare	$0.15	$0.5	Source09/08/2026
	CoreWeave	Via OpenRoutercoreweave/fp8	$0.15	$0.5	Source09/08/2026
	DeepInfra	Via OpenRouterdeepinfra/fp4	$0.075	$0.25	Source09/08/2026
	DigitalOcean	Via OpenRouterdigitalocean	$0.15	$0.5	Source09/08/2026
	Fireworks	Via OpenRouterfireworks	$0.15	$0.5	Source09/08/2026
	Friendli	Via OpenRouterfriendli	$0.15	$0.5	Source09/08/2026
	GMICloud	Via OpenRoutergmicloud/fp8	$0.075	$0.25	Source09/08/2026
	Io Net	Via OpenRouterio-net/fp8	$0.15	$0.5	Source09/08/2026
	Makora	Via OpenRoutermakora	$0.14	$0.47	Source09/08/2026
	Modal	Via OpenRoutermodal/fp8	$0.15	$0.4999	Source09/08/2026
	Morph	Via OpenRoutermorph/fp8	$0.388	$1.358	Source09/08/2026
	NextBit	Via OpenRouternextbit/fp8	$0.15	$0.5	Source09/08/2026
	Novita	Via OpenRouternovita/fp8	$0.075	$0.25	Source09/08/2026
	Parasail	Via OpenRouterparasail/fp8	$0.15	$0.5	Source09/08/2026
	Phala	Via OpenRouterphala/fp8	$0.15	$0.5	Source09/08/2026
	Reka	Via OpenRouterreka/fp8	$0.15	$0.5	Source09/08/2026
	Relace	Via OpenRouterrelace/fp4	Lowest listed price: $0.0713	Lowest listed price: $0.2375	Source09/08/2026
	Sail Research	Via OpenRoutersail-research/fp8	$0.15	$0.5	Source09/08/2026
	SiliconFlow	Via OpenRoutersiliconflow/fp8	$0.15	$0.5	Source09/08/2026
	StreamLake	Via OpenRouterstreamlake/fp8	$0.135	$0.45	Source09/08/2026
	Together	Via OpenRoutertogether	$0.15	$0.5	Source09/08/2026
	Venice	Via OpenRoutervenice	$0.15	$0.5	Source09/08/2026
	Wafer	Via OpenRouterwafer	$0.1	$0.35	Source09/08/2026
	Z.AI	Via OpenRouterz-ai/fp8	$0.075	$0.25	Source09/08/2026

Performance

Shared benchmarks

Only published results with the same benchmark version, task, metric, and comparison cohort are paired. Different reasoning levels, agents, harnesses, or output limits appear directly in the table.

Capability profile from matched benchmarks

Each axis averages directly matched benchmark families. A value of 100 means the stronger value within this pair, not a universal quality score.

GPT-5.5

GLM-5.3-Flash

Coding: 97.4 / 71 (4 benchmark families)

Reasoning: 100 / 92.7 (1 benchmark family)

Knowledge: 100 / 97.6 (1 benchmark family)

Finance: 96.2 / 95.6 (3 benchmark families)

Legal: 81.9 / 99 (3 benchmark families)

Agentic tasks: 100 / 73.5 (2 benchmark families)

Multimodal: 100 / 97.4 (1 benchmark family)

Cybersecurity: 100 / 88.8 (1 benchmark family)

18 matched rows from 18 benchmark families were considered. The radar shows 8 of 10 comparable categories.

GPT-5.5GLM-5.3-Flash

Code MigrationOverall. Higher is better. No documented setup difference

GPT-5.545.161 %

GLM-5.3-Flash20.515 %

CyberBenchOverall. Higher is better. No documented setup difference

GPT-5.580.508 %

GLM-5.3-Flash71.488 %

EMBOverall. Higher is better. No documented setup difference

GPT-5.564.543 %

GLM-5.3-Flash55.932 %

Finance Agent (v2)Overall. Higher is better. No documented setup difference

GPT-5.551.76 %

GLM-5.3-Flash57.85 %

GPQA DiamondOverall. Higher is better. No documented setup difference

GPT-5.593.182 %

GLM-5.3-Flash86.364 %

Harvey's Legal Agent BenchmarkOverall · Task fully resolved. Higher is better. No documented setup difference

GPT-5.53.75 %

GLM-5.3-Flash6.667 %

Legal Research BenchOverall · All-pass. Higher is better. No documented setup difference

GPT-5.540.385 %

GLM-5.3-Flash45.192 %

LegalBenchOverall. Higher is better. No documented setup difference

GPT-5.586.515 %

GLM-5.3-Flash83.928 %

LiveCodeBench v6Overall. Higher is better. No documented setup difference

GPT-5.585.296 %

GLM-5.3-Flash80.51 %

MedScribeOverall. Higher is better. No documented setup difference

GPT-5.586.868 %

GLM-5.3-Flash88.936 %

MMLU-ProOverall. Higher is better. No documented setup difference

GPT-5.588.144 %

GLM-5.3-Flash86.059 %

MMMU-ProOverall. Higher is better. No documented setup difference

GPT-5.588.266 %

GLM-5.3-Flash86.012 %

Key to the marks:better valuebetter, but not conclusivetie

Benchmark scores for GPT-5.5 and GLM-5.3-Flash
Benchmark and task	GPT-5.5	GLM-5.3-Flash	Source
Code MigrationOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner45.161 %	20.515 %	Vals AI Source details Data as of: 09/03/2026
CyberBenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner80.508 %	71.488 %	Vals AI Source details Data as of: 09/01/2026
EMBOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner64.543 %	55.932 %	Vals AI Source details Data as of: 09/03/2026
Finance Agent (v2)Overall Test details No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better	51.76 %	Winner57.85 %	Vals AI Source details Data as of: 09/03/2026
GPQA DiamondOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner93.182 %	86.364 %	Vals AI Source details Data as of: 09/01/2026
Harvey's Legal Agent BenchmarkOverall · Task fully resolved Test details No documented difference in the test setupVersion: 1Metric: task resolution rateScoring: Higher is better	3.75 %	Winner6.667 %	Vals AI Source details Data as of: 09/03/2026
Legal Research BenchOverall · All-pass Test details No documented difference in the test setupVersion: 1Metric: all-pass rateScoring: Higher is better	40.385 %	Winner45.192 %	Vals AI Source details Data as of: 09/03/2026
LegalBenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner86.515 %	83.928 %	Vals AI Source details Data as of: 09/01/2026
LiveCodeBench v6Overall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner85.296 %	80.51 %	Vals AI Source details Data as of: 09/01/2026
MedScribeOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	86.868 %	Winner88.936 %	Vals AI Source details Data as of: 09/03/2026
MMLU-ProOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner88.144 %	86.059 %	Vals AI Source details Data as of: 09/01/2026
MMMU-ProOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner88.266 %	86.012 %	Vals AI Source details Data as of: 09/01/2026
SkillsBenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is betterSettings: Harness: OpenHands	Winner62.209 %	40.159 %	Vals AI Source details Data as of: 09/01/2026
SWE-bench VerifiedOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	82.6 %	Winner92 %	Vals AI Source details Data as of: 09/01/2026
TaxEval v2Overall Test details No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better	74.98 %	Winner75.593 %	Vals AI Source details Data as of: 09/01/2026
Terminal-Bench 2.1Overall Test details No documented difference in the test setupVersion: 2.1Metric: accuracyScoring: Higher is better	Winner76.404 %	62.921 %	Vals AI Source details Data as of: 09/03/2026
Vals IndexOverall Test details No documented difference in the test setupVersion: 2Metric: weighted index scoreScoring: Higher is better	Winner57.411 %	47.216 %	Vals AI Source details Data as of: 09/03/2026
Vibe Code Bench v1.1Overall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is betterSettings: Harness: OpenHands	Winner69.847 %	30.759 %	Vals AI Source details Data as of: 09/03/2026
Key to the marks:better valuebetter, but not conclusivetie

Our model tests

Community tests you can inspect

Compare how the models respond to the same prompt. Each test shows the first attempt, with no subsequent fixes to the generated code. These results do not contribute to an overall score.

Pelican on a bicycle

A community classic for free-form SVG drawing.

GPT-5.5

The API response was not fully received. The model was not evaluated.

First attempt

Run date: 7 Sept 2026
API provider: openrouter
Requested API model: openai/gpt-5.5
Pinned endpoint: OpenAI | openai/gpt-5.5-20260423
Reasoning setting: high
Temperature: Provider default
Token limit including reasoning: 8,192 tokens
Test protocol: community-visual-tests-v1
Technical checks: Failed

Not yet visually reviewed. A successful recording does not confirm correct physics or full compliance with the prompt.

GLM-5.3-Flash

API access was unavailable for this run. The model was not evaluated.

First attempt

Run date: 7 Sept 2026
API provider: openrouter
Requested API model: z-ai/glm-5.3-flash
Pinned endpoint: Z.AI | z-ai/glm-5.3-flash-20260826
Reasoning setting: high
Temperature: Provider default
Token limit including reasoning: 8,192 tokens
Test protocol: community-visual-tests-v1
Technical checks: Not run

Not yet visually reviewed. A successful recording does not confirm correct physics or full compliance with the prompt.

Prompt and test conditions

Generate an SVG of a pelican riding a bicycle

Token limit including reasoning: 8,192 tokens

Task origin (Simon Willison)

How to read this comparison

Winning one benchmark is not an overall verdict

Your workload, budget, and required context length matter most. A coding benchmark says little about visual understanding or agent performance.

The standard price table uses direct developer rates. The provider comparison labels OpenRouter endpoints, regions, and special tariffs separately.

Every result links to its measurement source and retrieval date. Labels distinguish vendor reports, official benchmark leaderboards, and independent evaluations. Disputed or archived results are excluded.

More matchups

Compare GPT-5.5 and GLM-5.3-Flash with other leading models using the same data and benchmark logic.

View the complete LLM comparison