GLM-5.3-Flash vs o3-pro
Comparing GLM-5.3-Flash and o3-pro across benchmarks, pricing, and capabilities.
Zhipu AI · OpenAI · Updated for 2026
Which is better?
GLM-5.3-Flash and o3-pro trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
On price, GLM-5.3-Flash is roughly 147.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GLM-5.3-Flash also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.
Based on current benchmark, pricing, and model metadata for 2026.
Choose GLM-5.3-Flash
- cost matters — it's about 147.4x cheaper per token
- you process long inputs — it offers a 1,048,576 token context window
- you want the most recent training data — it shipped Aug 2026
- you need open weights you can self-host or fine-tune
Choose o3-pro
- you want predictable pricing at $20.00/M input and $80.00/M output
At a glance
The differences that matter most.
Performance Benchmarks
Comparative analysis across standard metrics
GLM-5.3-Flash and o3-prodon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.
Arena Performance
Playground indexes and blind preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GLM-5.3-Flash ($0.15/1M tokens) is 133.3x cheaper than o3-pro ($20.00/1M tokens).
For output processing, GLM-5.3-Flash ($0.50/1M tokens) is 160.0x cheaper than o3-pro ($80.00/1M tokens).
In conclusion, o3-pro is more expensive than GLM-5.3-Flash.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GLM-5.3-Flash accepts 1,048,576 input tokens compared to o3-pro's 200,000 tokens. GLM-5.3-Flash can generate longer responses up to 131,072 tokens, while o3-pro is limited to 100,000 tokens.
Input Capabilities
Supported data types and modalities
Both GLM-5.3-Flash and o3-pro support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GLM-5.3-Flash
o3-pro
License
Usage and distribution terms
GLM-5.3-Flash is licensed under MIT, while o3-pro uses a proprietary license.
License differences may affect how you can use these models in commercial or open-source projects.
MIT
Open weights
Proprietary
Closed source
Release Timeline
When each model was launched
GLM-5.3-Flash was released on 2026-08-26, while o3-pro was released on 2025-06-10.
GLM-5.3-Flash is 15 months newer than o3-pro.
Aug 26, 2026
0 days ago
1.2yr newerJun 10, 2025
1.2 years ago
Knowledge Cutoff
When training data ends
o3-pro has a documented knowledge cutoff of 2024-05-31, while GLM-5.3-Flash's cutoff date is not specified.
We can confirm o3-pro's training data extends to 2024-05-31, but cannot make a direct comparison without GLM-5.3-Flash's cutoff date.
—
May 2024
Provider Availability
GLM-5.3-Flash is available from DeepInfra, Novita, ZAI. o3-pro is available from OpenAI.
GLM-5.3-Flash
o3-pro
Outputs Comparison
Judge for yourself.
Run your own prompts against GLM-5.3-Flash and o3-pro side-by-side, then vote on the output you prefer.
FAQ
Common questions about GLM-5.3-Flash vs o3-pro.