Qwen2 7B at FP16 needs 15.2 GB for its weights and 19.0 GB in total at 8K context with 8 concurrent users. That means it fits on a single RTX 4090 24GB. 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× RTX | 24 GB | 19.0 GB | 42.99 | 515.9 | 3.08 s | $0.2154 | ✓ |
| 2× RTX | 48 GB | 19.0 GB | 73.09 | 1754 | 1.56 s | $0.1267 | ✓ |
| 4× RTX | 96 GB | 19.0 GB | 146.2 | 7016 | 792.6 ms | $0.0633 | ✓ |
| 8× RTX | 192 GB | 19.0 GB | 292.3 | 28065 | 411.3 ms | $0.0317 | ✓ |
| Context | Concurrent users | KV per request | Fits? |
|---|---|---|---|
| 4K | 37 | 240.5 MB | ✓ fits |
| 8K | 18 | 481.0 MB | ✓ fits |
| 33K | 4 | 1.88 GB | ✓ fits |
| 66K | 2 | 3.76 GB | ✓ fits |
| 131K | 1 | 7.52 GB | ✓ fits |
| GPU | GPUs | Aggregate tok/s | Cost / 1M tok |
|---|---|---|---|
| RTX 3090 24GB | 1× | 479.1 | $0.1450 |
| RTX 5090 32GB | 1× | 917.2 | $0.1514 |
| AMD MI300X 192GB | 1× | 2713 | $0.2560 |
| V100 SXM2 32GB | 1× | 460.6 | $0.3015 |
| A100 40GB SXM4 | 1× | 793.3 | $0.3151 |
| AMD MI325X 288GB | 1× | 3071 | $0.3166 |
Yes. Qwen2 7B at FP16 needs 19.0 GB including the KV cache, and RTX 4090 24GB has 24 GB — so it fits on a single GPU.
42.99 tokens/sec per stream and 515.9 tok/s aggregate with continuous batching at 8 concurrent users. Time to first token is 3.08 s, and inter-token latency is 23.3 ms.
$0.2154 per 1M output tokens at 1× RTX 4090 24GB ($0.4000/hr). That is the marginal hardware cost — add idle capacity, ops, and egress for the real figure.
15.2 GB for the weights at FP16, plus 3.8 GB of KV cache for 8 concurrent requests at 8K context — 19.0 GB total. Every extra concurrent user at long context costs more, so leave headroom.
It works. Compare $0.2154 per 1M tokens against the alternatives below — the cheapest option that fits the same workload is 2× RTX 3080 10GB at $0.0840, and the fastest is 1× Cerebras CS-3 (WSE-3) at 10236 tok/s.
Same formulas, your context length, concurrency, and quantisation.