GLM-5.3-Flash vs GPT-5.1 Thinking
Comparing GLM-5.3-Flash and GPT-5.1 Thinking across benchmarks, pricing, and capabilities.
Zhipu AI · OpenAI · Updated for 2026
Which is better?
GLM-5.3-Flash and GPT-5.1 Thinking trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.
On price, GLM-5.3-Flash is roughly 14.5x 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 14.5x 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 GPT-5.1 Thinking
- you want predictable pricing at $1.25/M input and $10.00/M output
At a glance
The differences that matter most.
Performance Benchmarks
Comparative analysis across standard metrics
GLM-5.3-Flash and GPT-5.1 Thinkingdon'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 8.3x cheaper than GPT-5.1 Thinking ($1.25/1M tokens).
For output processing, GLM-5.3-Flash ($0.50/1M tokens) is 20.0x cheaper than GPT-5.1 Thinking ($10.00/1M tokens).
In conclusion, GPT-5.1 Thinking 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 GPT-5.1 Thinking's 400,000 tokens. GLM-5.3-Flash can generate longer responses up to 131,072 tokens, while GPT-5.1 Thinking is limited to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both GLM-5.3-Flash and GPT-5.1 Thinking support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GLM-5.3-Flash
GPT-5.1 Thinking
License
Usage and distribution terms
GLM-5.3-Flash is licensed under MIT, while GPT-5.1 Thinking 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 GPT-5.1 Thinking was released on 2025-11-12.
GLM-5.3-Flash is 10 months newer than GPT-5.1 Thinking.
Aug 26, 2026
0 days ago
9mo newerNov 12, 2025
9 months ago
Knowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
GLM-5.3-Flash is available from DeepInfra, Novita, ZAI. GPT-5.1 Thinking is available from OpenAI.
GLM-5.3-Flash
GPT-5.1 Thinking
Outputs Comparison
Judge for yourself.
Run your own prompts against GLM-5.3-Flash and GPT-5.1 Thinking side-by-side, then vote on the output you prefer.
FAQ
Common questions about GLM-5.3-Flash vs GPT-5.1 Thinking.