GPT-OSS 20B needs ~18.9 GB VRAM. NVIDIA A30 24GB has 24.0 GB. With Q4_K_M quantization, expect ~140 tok/s.
Operating mode
Interactive favors responsiveness, while light API and scale-out lean harder on serving readiness. The fit stays the same, but the recommendation lens changes.
Current mode
Balanced
Balanced for general local use. Keeps the ranking neutral across personal and serving workflows.
Select quantization to explore
Fit status
Runs well
Decode
139.7 tok/s
TTFT
1386 ms
Safe context
50K
Memory
18.9 GB / 24.0 GB
This setup is broadly balanced for this model.
No major red flags
This recommendation has enough memory headroom and acceptable estimated speed for the selected workload.
| Workload | Grade | Fit | Decode | TTFT | Context |
|---|---|---|---|---|---|
| Chat | S | Runs well | 139.7 tok/s | 756 ms | 50K |
| Coding | S | Runs well | 139.7 tok/s | 1386 ms | 50K |
| Agentic Coding | S | Tight fit | 139.7 tok/s | 2016 ms | 50K |
| Reasoning | S | Runs well | 139.7 tok/s | 1638 ms | 50K |
| RAG | S | Tight fit | 139.7 tok/s | 2520 ms | 50K |
Inference speed
Estimated decode speed (tokens/sec) for GPT-OSS 20B at Q4_K_M across popular GPUs and Apple Silicon, using the fastest local runtime per device. Fastest is RTX 5090 32GB at ~231 tok/s. Speed is memory-bandwidth bound, so cards that fit the whole model in VRAM run far faster than ones that offload to system RAM.
| GPU / Mac | Memory | Quant | Speed (tok/s) | Fits? |
|---|---|---|---|---|
| 32 GB | Q4_K_M | 230.5 | Fits | |
| 24 GB | Q4_K_M | 147.1 | Fits | |
RX 7900 XTX 24GB | 24 GB | Q4_K_M | 132.7 | Fits |
| 24 GB | Q4_K_M | 125.8 | Fits | |
Mac Studio M3 Ultra 256GB | 256 GB | Q4_K_M | 106.9 | Fits |
Mac Studio M2 Ultra 128GB | 128 GB | Q4_K_M | 89.1 | Fits |
Mac Studio M1 Ultra 128GB | 128 GB | Q4_K_M | 84.5 | Fits |
| 16 GB | Q4_K_M | 68.2 | Heavy offload | |
MacBook Pro M4 Max 128GB | 128 GB | Q4_K_M | 66.0 | Fits |
MacBook Pro M4 Max 64GB | 64 GB | Q4_K_M | 66.0 | Fits |
MacBook Pro M3 Max 64GB | 64 GB | Q4_K_M | 46.1 | Fits |
MacBook Pro M1 Max 64GB | 64 GB | Q4_K_M | 42.2 | Fits |
MacBook Pro M4 Pro 48GB | 48 GB | Q4_K_M | 40.4 | Fits |
| 12 GB | Q4_K_M | 24.2 | Too big | |
| 12 GB | Q4_K_M | 15.2 | Too big | |
| 8 GB | Q4_K_M | 5.7 | Too big |
Estimates for single-stream decoding at Q4_K_M; real tokens/sec varies with prompt length, context, batch size, and runtime build. Prompt processing (prefill) is faster than the decode figures shown here.
How GPT-OSS 20B (21B params) fits at each quantization level on NVIDIA A30 24GB (24.0 GB usable).
| Quant | Bits | VRAM | Quality | Fit |
|---|---|---|---|---|
Q2_K | 2 | 8.2 GB | Low | S86 |
Q3_K_S | 3 | 10.3 GB | Low | S88 |
NVFP4 | 4 | 11.8 GB | Medium | S89 |
Q4_K_M | 4 | 12.8 GB | Medium | S89 |
Q5_K_M | 5 | 15.1 GB | High | S88 |
Q6_KBest for your GPU | 6 | 17.2 GB | High | S88 |
Q8_0 | 8 | 22.5 GB | Very High | F0 |
F16 | 16 | 43.1 GB | Maximum | F0 |
Copy-paste commands to run GPT-OSS 20B on your machine.
Run
ollama run gpt-ossYour hardware
| Model | Params | Grade | Decode | Capabilities |
|---|---|---|---|---|
| 30.5B | S | 110 tok/s | ||
| 27B | S | 47.7 tok/s | ||
| 27B | S | 47.9 tok/s | ||
| 30B | S | 113.8 tok/s | ||
| 35B | A | 61.6 tok/s |
Yes, NVIDIA A30 24GB can run GPT-OSS 20B with a S grade (Runs well). Expected decode speed: 139.7 tok/s.
GPT-OSS 20B (21B parameters) requires approximately 18.9 GB of memory with Q4_K_M quantization.
The recommended quantization for GPT-OSS 20B is Q4_K_M, which balances quality and memory efficiency.
On NVIDIA A30 24GB, GPT-OSS 20B achieves approximately 139.7 tokens per second decode speed with a time-to-first-token of 1386ms using Q4_K_M quantization.
For coding workloads, GPT-OSS 20B on NVIDIA A30 24GB receives a S grade with 139.7 tok/s and 50K context.
On NVIDIA A30 24GB, GPT-OSS 20B can safely use up to 50K tokens of context. The model's official context limit is 128K, but available memory constrains the safe maximum.
Paste this snippet into any page to show a live fit card.
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