Llama 3.1 405B at AWQ 4-bit needs 222.8 GB for its weights and 256.6 GB in total at 8K context with 8 concurrent users. That means it needs 2× H200 SXM5 141GB. 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× H200 | 141 GB | 256.6 GB | 0.000 | 0.000 | — | — | ✗ |
| 2× H200 | 282 GB | 256.6 GB | 20.95 | 502.9 | 6.78 s | $4.42 | ✓ |
| 4× H200 | 564 GB | 256.6 GB | 41.91 | 2012 | 3.41 s | $2.21 | ✓ |
| 8× H200 | 1128 GB | 256.6 GB | 83.82 | 8046 | 1.72 s | $1.10 | ✓ |
| Context | Concurrent users | KV per request | Fits? |
|---|---|---|---|
| 4K | 28 | 2.11 GB | ✓ fits |
| 8K | 14 | 4.23 GB | ✓ fits |
| 33K | 3 | 16.91 GB | ✓ fits |
| 66K | 1 | 33.82 GB | ✓ fits |
| 131K | 0 | 67.65 GB | ✗ does not fit |
| GPU | GPUs | Aggregate tok/s | Cost / 1M tok |
|---|---|---|---|
| L40S 48GB | 8× | 1448 | $1.07 |
| A100 80GB SXM4 | 4× | 838.2 | $1.59 |
| H100 SXM5 80GB | 4× | 1404 | $1.98 |
| B200 SXM 192GB | 2× | 838.2 | $3.98 |
| AMD MI325X 288GB | 1× | 184.9 | $5.26 |
| B300 SXM 288GB | 1× | 246.5 | $9.01 |
Yes, but it needs 2× H200 SXM5 141GB. At AWQ 4-bit the total footprint is 256.6 GB (222.8 GB of weights plus 33.8 GB of KV cache at 8K × 8 concurrent users), against 282 GB of available VRAM across 2 GPUs.
20.95 tokens/sec per stream and 502.9 tok/s aggregate with continuous batching at 8 concurrent users. Time to first token is 6.78 s, and inter-token latency is 47.7 ms.
$4.42 per 1M output tokens at 2× H200 SXM5 141GB ($4.00/hr). That is the marginal hardware cost — add idle capacity, ops, and egress for the real figure.
222.8 GB for the weights at AWQ 4-bit, plus 33.8 GB of KV cache for 8 concurrent requests at 8K context — 256.6 GB total. Every extra concurrent user at long context costs more, so leave headroom.
It works. Compare $4.42 per 1M tokens against the alternatives below — the cheapest option that fits the same workload is 8× A100 40GB SXM4 at $0.7697, and the fastest is 8× Cerebras CS-3 (WSE-3) at 33527 tok/s.
Same formulas, your context length, concurrency, and quantisation.