GPT-OSS 20B
21B MoEOpenAI GPT-OSS
OpenAI open-weight MoE (21B total / 3.6B active), shipped natively in MXFP4 — ~12.8GB runs on a 16GB card with no quality tax. Only 3.6B active params means CPU-offload stays usable.
131K
Max Context
3
Quant Variants
GGUF MXFP4
Best Quality
100.0%
Accuracy Retained
Quantization Variants
Per-quant VRAM, quality loss, and inference speed on RTX 4090
Measured = site benchmarks · Estimated = formula · Community = public reports
Similar models
Compare with GPT-OSS 120BGPT-OSS 120B
OpenAI GPT-OSS
The big GPT-OSS (117B total / 5.1B active). Native MXFP4 checkpoint is ~61GB — fits one 80GB card or a 128GB unified-memory Mac. Partial offload on 24GB consumer cards is slow but works.
Qwen3 30B-A3B Instruct
Alibaba Qwen3
Qwen3 MoE with only 3B active params. Q4 ~19GB file; outperforms QwQ-32B on 16GB cards.
Seed-OSS 36B Instruct
ByteDance Seed
Dense 36B with a native 512K context. Q4 weights are ~22GB, which lands on a 24GB card or a 2×16GB split — but the context is the real cost: 512K of KV cache is roughly 128GB on its own, so budget context first and weights second.
Qwen2.5 32B Instruct
Alibaba Qwen2.5
Near-GPT-4 reasoning on a 24GB VRAM card (Q4_K_S). Groundbreaking value.
How to actually run this
Deployment guides for this model and this class of hardware.
- Run GPT-OSS 20B (and 120B) locally without re-quantizing 9 min·Intermediate·covers this model
- What Can You Run on RTX 4060 Ti 16G? 7 min·Beginner·covers this model
- Mac M3 Pro: Realistic Model Limits 6 min·Beginner·covers this model
- WSL2 + Ollama GPU Passthrough on Windows 10 min·Intermediate·covers this model