Qwen 3 8B at FP16 needs 16.0 GB for its weights and 25.7 GB in total at 8K context with 8 concurrent users. That means it fits on a single Mac M2 Ultra (192GB unified). Every figure is computed by tokcalc's open-source capacity model.
| GPUs | Total VRAM | VRAM needed | Decode tok/s | Aggregate tok/s | TTFT | Cost / 1M tok | Fits? |
|---|---|---|---|---|---|---|---|
| 1× Mac | 192 GB | 25.7 GB | 32.50 | 390.0 | 9.77 s | — | ✓ |
| 2× Mac | 384 GB | 25.7 GB | 55.25 | 1326 | 4.90 s | — | ✓ |
| 4× Mac | 768 GB | 25.7 GB | 110.5 | 5304 | 2.47 s | — | ✓ |
| 8× Mac | 1536 GB | 25.7 GB | 221.0 | 21216 | 1.25 s | — | ✓ |
| Context | Concurrent users | KV per request | Fits? |
|---|---|---|---|
| 4K | 291 | 618.5 MB | ✓ fits |
| 8K | 145 | 1.21 GB | ✓ fits |
| 33K | 36 | 4.83 GB | ✓ fits |
| 66K | 18 | 9.66 GB | ✓ fits |
| 131K | 9 | 19.33 GB | ✓ fits |
| GPU | GPUs | Aggregate tok/s | Cost / 1M tok |
|---|---|---|---|
| RTX 5090 32GB | 1× | 873.6 | $0.1590 |
| AMD MI300X 192GB | 1× | 2584 | $0.2688 |
| V100 SXM2 32GB | 1× | 438.8 | $0.3166 |
| A100 40GB SXM4 | 1× | 755.6 | $0.3309 |
| AMD MI325X 288GB | 1× | 2925 | $0.3324 |
| A100 80GB SXM4 | 1× | 975.0 | $0.3419 |
Yes. Qwen 3 8B at FP16 needs 25.7 GB including the KV cache, and Mac M2 Ultra (192GB unified) has 192 GB — so it fits on a single GPU.
32.50 tokens/sec per stream and 390.0 tok/s aggregate with continuous batching at 8 concurrent users. Time to first token is 9.77 s, and inter-token latency is 30.8 ms.
— per 1M output tokens at 1× Mac M2 Ultra (192GB unified). That is the marginal hardware cost — add idle capacity, ops, and egress for the real figure.
16.0 GB for the weights at FP16, plus 9.7 GB of KV cache for 8 concurrent requests at 8K context — 25.7 GB total. Every extra concurrent user at long context costs more, so leave headroom.
It works. Compare — per 1M tokens against the alternatives below — the cheapest option that fits the same workload is 4× RTX 3080 10GB at $0.0441, and the fastest is 1× Cerebras CS-3 (WSE-3) at 9750 tok/s.
Same formulas, your context length, concurrency, and quantisation.