Can I Run GPT-OSS on Apple M1?
Written by Jakub Rusinowski · Last updated August 15, 2026
Only with offload — GPT-OSS 20B at MXFP4 needs 12.3 GB at 8K context (11.1 GB weights + 1.2 GB KV cache/overhead) against the Apple M1's 12 GB usable memory, so part of it spills onto CPU/system RAM and speed drops sharply.
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Apple M1 Specs
| VRAM | 16 GB unified memory |
| Memory Bandwidth | 68 GB/s |
GPT-OSS 20B on the Apple M1: VRAM by quantization
| Quant | VRAM needed | Fits 16 GB? | Max context | Whole PC |
|---|---|---|---|---|
| F16 | 43 GB | ✗ No | — | — |
| Q8_0 | 23.4 GB | ✗ No | — | — |
| Q6_K | 18.3 GB | ✗ No | — | — |
| Q5_K_M | 16 GB | ✗ No | — | — |
| Q4_K_M | 13.8 GB | ✗ No | — | — |
| Q3_K_M | 10.1 GB | ✓ Yes | 32K | — |
| Q2_K | 8.1 GB | ✓ Yes | 64K | — |
Assumes an 8K-token context with an f16 KV cache. A longer window needs more; a quantized KV cache needs less. “Max context” is the largest window that still fits in 16 GB of unified memory. Figures are estimates from parameter count, quantization and memory bandwidth — the analyzer lets you tune KV-cache quant and context.
Context costs VRAM too. At MXFP4 on the Apple M1: 8K 12.3 GB ✗ · 32K 13.5 GB ✗ · 128K 18.3 GB ✗. Past 8K it no longer fits 16 GB — a q8_0 KV cache buys roughly half of that back, which the calculator will price for you.
No compatible GPU? GPT-OSS 20B on 16 GB of system RAM, CPU only: runs.
Why It Does Not Fit
Every GPT-OSS variant requires more VRAM than the Apple M1 provides (16 GB).
Nearest GPU That Fits
AMD Radeon RX 7900 XT (20 GB VRAM).
GPT-OSS needs ~12 GB but this GPU has 16 GB. Rent a RTX 4090 (24 GB)-class GPU by the hour instead of buying one:
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Cloud rates verified 2026-07 — estimates, and marketplace prices vary. Buying price is GPU MSRP only, not a full PC.
FAQ
Is the Apple M1 enough to run GPT-OSS locally?
Only with offload — GPT-OSS 20B at MXFP4 needs 12.3 GB at 8K context (11.1 GB weights + 1.2 GB KV cache/overhead) against the Apple M1's 12 GB usable memory, so part of it spills onto CPU/system RAM and speed drops sharply.
What's the cheapest GPU that runs GPT-OSS?
The AMD Radeon RX 7900 XT (20 GB VRAM) is the cheapest upgrade that fits it.
Every GPT-OSS size on the Apple M1
| Size | VRAM at 8K | Verdict | Speed |
|---|---|---|---|
| GPT-OSS 120B | 71.9 GB | Does not fit | — |
| GPT-OSS 20B | 12.3 GB | Runs at Q3_K_M | — |
GPT-OSS on Other GPUs
- GPT-OSS on NVIDIA GeForce RTX 5080
- GPT-OSS on NVIDIA GeForce RTX 5070 Ti
- GPT-OSS on NVIDIA GeForce RTX 5060 Ti 16GB
- GPT-OSS on NVIDIA GeForce RTX 4080 Super
- GPT-OSS on NVIDIA GeForce RTX 4080
Popular Models on the Apple M1
VRAM Tier
Troubleshooting
- Ollama: "model requires more system memory than is available"
- Out of memory at long context (the KV cache, not the weights)
Buying Guide
← Can I Run It? | GPT-OSS Model Page | Apple M1 GPU Page | VRAM calculator | Check Your Hardware