GPT OSS 120B vs GPT OSS 20B
Side-by-side comparison of VRAM requirements, quantization, context length, and hardware compatibility.
Specifications
| GPT OSS 120B | GPT OSS 20B | |
|---|---|---|
| Parameters | 120.4B | 21.5B |
| Context | 131K | 131K |
| Architecture | GptOssForCausalLM | GptOssForCausalLM |
| License | Apache 2.0 | Apache 2.0 |
| Downloads | 4.5M | 7.6M |
| Released | Aug 2025 | Aug 2025 |
VRAM by Quantization: GPT OSS 120B vs GPT OSS 20B
| Quantization | Bits | GPT OSS 120B VRAM | GPT OSS 20B VRAM |
|---|---|---|---|
| Q2_K | 3.40 | 51.6 GB | 9.5 GB |
| Q3_K_M | 3.90 | 59.1 GB | 10.9 GB |
| Q3_K_S | 3.50 | 53.1 GB | 9.8 GB |
| Q4_0 | 4.00 | 60.6 GB | 11.1 GB |
| Q4_K_M | 4.80 | 72.7 GB | 13.3 GB |
| Q5_K_M | 5.70 | 86.2 GB | 15.7 GB |
| Q6_K | 6.60 | 99.8 GB | 18.1 GB |
| Q8_0 | 8.00 | 120.8 GB | 21.9 GB |
Verdict
GPT OSS 20B needs less VRAM at Q4_K_M (13.3 GB vs 72.7 GB), so it fits on smaller GPUs. GPT OSS 20B is the more widely downloaded of the two.
Frequently Asked Questions
- Which needs less VRAM, GPT OSS 120B or GPT OSS 20B?
At Q4_K_M, GPT OSS 120B needs 72.7 GB and GPT OSS 20B needs 13.3 GB, so GPT OSS 20B is the lighter option to run locally.
- Which has a longer context window, GPT OSS 120B or GPT OSS 20B?
GPT OSS 120B supports 131,072 tokens and GPT OSS 20B supports 131,072 tokens.
- What is the difference between GPT OSS 120B and GPT OSS 20B?
GPT OSS 120B is a 120.4B model from OpenAI (GPT-OSS family), while GPT OSS 20B is a 21.5B model from OpenAI (GPT-OSS family). Compare their VRAM requirements above to see which fits your GPU or Mac.