GLM-4.5 vs GPT OSS 20B
GLM-4.5 significantly outperforms across most benchmarks. GPT OSS 20B is 8.0x cheaper per token.
Zhipu AI · OpenAI · Updated for 2026
Which is better?
GLM-4.5 outperforms in 3 benchmarks (GPQA, Humanity's Last Exam, TAU-bench Retail), while GPT OSS 20B is better at 0 benchmarks. GLM-4.5 significantly outperforms across most benchmarks.
On price, GPT OSS 20B is roughly 8.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Based on current benchmark, pricing, and model metadata for 2026.
Choose GLM-4.5
- you want the strongest raw capability — it leads on 3 of 3 shared benchmarks
Choose GPT OSS 20B
- cost matters — it's about 8.0x cheaper per token
- you want the most recent training data — it shipped Aug 2025
At a glance
The differences that matter most.
Performance Benchmarks
Comparative analysis across standard metrics
GLM-4.5 outperforms in 3 benchmarks (GPQA, Humanity's Last Exam, TAU-bench Retail), while GPT OSS 20B is better at 0 benchmarks.
GLM-4.5 significantly outperforms across most benchmarks.
Arena Performance
Playground indexes and blind preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GLM-4.5 ($0.40/1M tokens) is 8.0x more expensive than GPT OSS 20B ($0.05/1M tokens).
For output processing, GLM-4.5 ($1.60/1M tokens) is 8.0x more expensive than GPT OSS 20B ($0.20/1M tokens).
In conclusion, GLM-4.5 is more expensive than GPT OSS 20B.*
* Using a 3:1 ratio of input to output tokens
Model Size
Parameter count comparison
GLM-4.5 has 334.1B more parameters than GPT OSS 20B, making it 1598.6% larger.
Context Window
Maximum input and output token capacity
Both models have the same input context window of 131,072 tokens. GLM-4.5 can generate longer responses up to 131,072 tokens, while GPT OSS 20B is limited to 32,768 tokens.
License
Usage and distribution terms
GLM-4.5 is licensed under MIT, while GPT OSS 20B uses Apache 2.0.
License differences may affect how you can use these models in commercial or open-source projects.
MIT
Open weights
Apache 2.0
Open weights
Release Timeline
When each model was launched
GLM-4.5 was released on 2025-07-28, while GPT OSS 20B was released on 2025-08-05.
GPT OSS 20B is 0 month newer than GLM-4.5.
Jul 28, 2025
1.1 years ago
Aug 5, 2025
1.1 years ago
1w newerKnowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
GLM-4.5 is available from DeepInfra, Fireworks, Novita. GPT OSS 20B is available from Novita, Fireworks, Groq, OpenAI.
GLM-4.5
GPT OSS 20B
Outputs Comparison
Judge for yourself.
Run your own prompts against GLM-4.5 and GPT OSS 20B side-by-side, then vote on the output you prefer.
FAQ
Common questions about GLM-4.5 vs GPT OSS 20B.