GPT-OSS 20B (MoE) at FP8 (E4M3) needs 20.9 GB for its weights and 22.6 GB in total at 8K context with 8 concurrent users. That means it fits on a single 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 | 22.6 GB | 1300 | 15600 | 149.9 ms | $0.0712 | ✓ |
| 2× H200 | 282 GB | 22.6 GB | 2210 | 53040 | 90.0 ms | $0.0419 | ✓ |
| 4× H200 | 564 GB | 22.6 GB | 4420 | 212160 | 60.0 ms | $0.0209 | ✓ |
| 8× H200 | 1128 GB | 22.6 GB | 8840 | 848640 | 45.0 ms | $0.0105 | ✓ |
| Context | Concurrent users | KV per request | Fits? |
|---|---|---|---|
| 4K | 1156 | 206.2 MB | ✓ fits |
| 8K | 587 | 412.3 MB | ✓ fits |
| 33K | 148 | 1.61 GB | ✓ fits |
| 66K | 74 | 3.22 GB | ✓ fits |
| 131K | 37 | 6.44 GB | ✓ fits |
| GPU | GPUs | Aggregate tok/s | Cost / 1M tok |
|---|---|---|---|
| RTX 5090 32GB | 1× | 5824 | $0.0238 |
| RTX 3090 24GB | 1× | 2472 | $0.0281 |
| RTX 4090 24GB | 1× | 3276 | $0.0339 |
| AMD MI300X 192GB | 1× | 17225 | $0.0403 |
| V100 SXM2 32GB | 1× | 2925 | $0.0475 |
| A100 40GB SXM4 | 1× | 5038 | $0.0496 |
Yes. GPT-OSS 20B (MoE) at FP8 (E4M3) needs 22.6 GB including the KV cache, and H200 SXM5 141GB has 141 GB — so it fits on a single GPU.
1300 tokens/sec per stream and 15600 tok/s aggregate with continuous batching at 8 concurrent users. Time to first token is 149.9 ms, and inter-token latency is 769.2 µs.
$0.0712 per 1M output tokens at 1× H200 SXM5 141GB ($4.00/hr). That is the marginal hardware cost — add idle capacity, ops, and egress for the real figure.
20.9 GB for the weights at FP8 (E4M3), plus 1.6 GB of KV cache for 8 concurrent requests at 8K context — 22.6 GB total. Every extra concurrent user at long context costs more, so leave headroom.
It works. Compare $0.0712 per 1M tokens against the alternatives below — the cheapest option that fits the same workload is 4× RTX 3080 10GB at $0.006615, and the fastest is 1× Cerebras CS-3 (WSE-3) at 65000 tok/s.
Same formulas, your context length, concurrency, and quantisation.