Qwen 3 4B at FP16 needs 8.0 GB for its weights and 17.7 GB in total at 8K context with 8 concurrent users. That means it fits on a single RTX 3090 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 | 17.7 GB | 76.05 | 912.6 | 3.72 s | $0.0761 | ✓ |
| 2× RTX | 48 GB | 17.7 GB | 129.3 | 3103 | 1.88 s | $0.0448 | ✓ |
| 4× RTX | 96 GB | 17.7 GB | 258.6 | 12411 | 954.3 ms | $0.0224 | ✓ |
| 8× RTX | 192 GB | 17.7 GB | 517.1 | 49645 | 492.2 ms | $0.0112 | ✓ |
| Context | Concurrent users | KV per request | Fits? |
|---|---|---|---|
| 4K | 26 | 618.5 MB | ✓ fits |
| 8K | 13 | 1.21 GB | ✓ fits |
| 33K | 3 | 4.83 GB | ✓ fits |
| 66K | 1 | 9.66 GB | ✓ fits |
| 131K | 0 | 19.33 GB | ✗ does not fit |
| GPU | GPUs | Aggregate tok/s | Cost / 1M tok |
|---|---|---|---|
| RTX 5090 32GB | 1× | 1747 | $0.0795 |
| RTX 4090 24GB | 1× | 982.8 | $0.1131 |
| AMD MI300X 192GB | 1× | 5168 | $0.1344 |
| V100 SXM2 32GB | 1× | 877.5 | $0.1583 |
| A100 40GB SXM4 | 1× | 1511 | $0.1654 |
| AMD MI325X 288GB | 1× | 5850 | $0.1662 |
Yes. Qwen 3 4B at FP16 needs 17.7 GB including the KV cache, and RTX 3090 24GB has 24 GB — so it fits on a single GPU.
76.05 tokens/sec per stream and 912.6 tok/s aggregate with continuous batching at 8 concurrent users. Time to first token is 3.72 s, and inter-token latency is 13.1 ms.
$0.0761 per 1M output tokens at 1× RTX 3090 24GB ($0.2500/hr). That is the marginal hardware cost — add idle capacity, ops, and egress for the real figure.
8.0 GB for the weights at FP16, plus 9.7 GB of KV cache for 8 concurrent requests at 8K context — 17.7 GB total. Every extra concurrent user at long context costs more, so leave headroom.
It works. Compare $0.0761 per 1M tokens against the alternatives below — the cheapest option that fits the same workload is 2× RTX 3080 10GB at $0.0441, and the fastest is 1× Cerebras CS-3 (WSE-3) at 19500 tok/s.
Same formulas, your context length, concurrency, and quantisation.