HomeCan I run it?Phi-4Phi-4 on an RTX 4090
Yes. Phi-4 at Q8_0 needs about 18.9 GB, and the GeForce RTX 4090 has 24.0 GB usable at a ~4k context.
Can I run Phi-4 on an RTX 4090?
Phi-4 at Q8_0 needs about 18.9 GB, and the GeForce RTX 4090 has 24.0 GB usable. That figure is 24 GB of VRAM on the spec sheet, of which 24.0 GB is usable for weights and cache, at 1008 GB/s memory bandwidth. Microsoft’s Phi-4, a dense 14B-class model often compared with other 12B–14B instruct weights. These are estimates from our formula, not measured benchmarks.
- Quant that fits
- Q8_0 Fits with headroom
- Memory needed
- 18.9 GB at Q8_0, ~4k context
- Usable VRAM
- 24.0 GB of 24 GB VRAM
- Est. tokens/sec
- 39–55 estimate
Memory at each quant
| Quant | Need vs 24.0 GB | Verdict |
|---|---|---|
| Q4_K_M | 11.2 GB | Q4Fits |
| Q8_0 | 18.9 GB | Q8Fits |
| FP16 | 34.7 GB | FP16Won’t fit |
Estimated tokens per second
Estimate: 39–55 tokens/sec at Q8_0. This is a bandwidth-derived range, not a bench. Efficiency is a 60–85% GPU band from How we calculate.
Context headroom
At Q8_0, this machine has headroom out to about 16k tokens under our KV estimate. Longer chats need more memory for the cache. Figures assume an FP16 KV cache.
| Context | KV cache (FP16) | Total at Q8_0 | Verdict |
|---|---|---|---|
| 4k | 0.8 GB | 18.9 GB | Fits |
| 8k | 1.7 GB | 19.8 GB | Fits |
| 16k | 3.4 GB | 21.4 GB | Fits |
| 32k | 6.7 GB | 24.8 GB | Won’t fit |
| 64k | 13.4 GB | 31.5 GB | Won’t fit |
| 128k | 26.8 GB | 44.9 GB | Won’t fit |
What to do instead
- Full hardware list: phi-4. Specs for this machine: GeForce RTX 4090.
Other hardware for Phi-4
- Phi-4 on an RTX 3060 12GBTight
- Phi-4 on an RTX 3070 TiWon’t fit
- Phi-4 on an RTX 3080Won’t fit
- Phi-4 on an RTX 4060 Ti 16GBFits
- Phi-4 on an RTX 4070 Ti SuperFits
- Phi-4 on an RTX 5070 TiFits
Other models on an RTX 4090
- Qwen3-32B on an RTX 4090Tight
- Qwen3-30B-A3B on an RTX 4090Tight
- Qwen3.8-27B on an RTX 4090Fits
- Gemma 3 27B on an RTX 4090Fits
- Gemma 4 31B on an RTX 4090Tight
- gpt-oss-20b on an RTX 4090Fits
Quick answers
- Can I run Phi-4 on an RTX 4090?
- Yes. Phi-4 at Q8_0 needs about 18.9 GB, and the GeForce RTX 4090 has 24.0 GB usable.
- How much VRAM does Phi-4 need?
- About 11.2 GB at Q4_K_M, 18.9 GB at Q8_0 and 34.7 GB at FP16, estimated for a ~4k context.
- How fast is Phi-4 on an RTX 4090?
- Our estimate is 39–55 tokens per second at Q8_0. It is not a measured benchmark.
- What context length can I use?
- At Q8_0, our KV estimate supports up to about 16k tokens before the cache pushes the total over usable memory.