Microsoft·Phi 4·Phi4FlashForCausalLM

Phi 4 Mini Flash Reasoning — Hardware Requirements & GPU Compatibility

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Phi 4 Mini Flash Reasoning is a 3.9B-parameter open language model from Microsoft in the Phi 4 family. It supports a context window of up to 262,144 tokens. At Q4_K_M it needs about 2.95 GB of VRAM — see which GPUs and Macs can run it below.

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Specifications

Publisher
Microsoft
Family
Phi 4
Parameters
3.9B
Architecture
Phi4FlashForCausalLM
Context Length
262,144 tokens
Vocabulary Size
200,064
Release Date
2025-12-10
License
MIT

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How Much VRAM Does Phi 4 Mini Flash Reasoning Need?

Select a quantization to see compatible GPUs below.

QuantizationBitsVRAM
Q2_K3.402.3 GB
Q3_K_M3.902.5 GB
Q4_K_M4.803.0 GB
Q5_K_M5.703.4 GB
Q6_K6.603.8 GB
Q8_08.004.5 GB

Which GPUs Can Run Phi 4 Mini Flash Reasoning?

Q4_K_M · 3.0 GB

Phi 4 Mini Flash Reasoning (Q4_K_M) requires 3.0 GB of VRAM to load the model weights. For comfortable inference with headroom for KV cache and system overhead, 4+ GB is recommended. Using the full 262K context window can add up to 42.6 GB, bringing total usage to 45.6 GB. 35 GPUs can run it, including NVIDIA GeForce RTX 5090, NVIDIA GeForce RTX 3090 Ti.

Which Devices Can Run Phi 4 Mini Flash Reasoning?

Q4_K_M · 3.0 GB

33 devices with unified memory can run Phi 4 Mini Flash Reasoning, including NVIDIA DGX H100, NVIDIA DGX A100 640GB.

Related Models

Frequently Asked Questions

How much VRAM does Phi 4 Mini Flash Reasoning need?

Phi 4 Mini Flash Reasoning requires 3.0 GB of VRAM at Q4_K_M, or 4.5 GB at Q8_0. Full 262K context adds up to 42.6 GB (45.6 GB total).

VRAM = Weights + KV Cache + Overhead

Weights = 3.9B × 4.8 bits ÷ 8 = 2.3 GB

KV Cache + Overhead 0.7 GB (at 2K context + ~0.3 GB framework)

KV Cache + Overhead 43.3 GB (at full 262K context)

VRAM usage by quantization

3.0 GB
45.6 GB

Learn more about VRAM estimation →

What's the best quantization for Phi 4 Mini Flash Reasoning?

For Phi 4 Mini Flash Reasoning, Q4_K_M (3.0 GB) offers the best balance of quality and VRAM usage. Q5_K_M (3.4 GB) provides better quality if you have the VRAM. The smallest option is Q2_K at 2.3 GB.

VRAM requirement by quantization

Q2_K
2.3 GB
Q3_K_M
2.5 GB
Q4_K_M
3.0 GB
Q5_K_M
3.4 GB
Q6_K
3.8 GB
Q8_0
4.5 GB

★ Recommended — best balance of quality and VRAM usage.

Learn more about quantization →

Can I run Phi 4 Mini Flash Reasoning on a Mac?

Phi 4 Mini Flash Reasoning requires at least 2.3 GB at Q2_K, which exceeds the unified memory of most consumer Macs. You would need a Mac Studio or Mac Pro with a high-memory configuration.

Can I run Phi 4 Mini Flash Reasoning locally?

Yes — Phi 4 Mini Flash Reasoning can run locally on consumer hardware. At Q4_K_M quantization it needs 3.0 GB of VRAM. Popular tools include Ollama, LM Studio, and llama.cpp.

How fast is Phi 4 Mini Flash Reasoning?

At Q4_K_M, Phi 4 Mini Flash Reasoning can reach ~988 tok/s on AMD Instinct MI300X. On NVIDIA GeForce RTX 4090: ~222 tok/s. Speed depends mainly on GPU memory bandwidth. Real-world results typically within ±20%.

tok/s = (bandwidth GB/s ÷ model GB) × efficiency

Example: AMD Instinct MI300X5300 ÷ 3.0 × 0.55 = ~988 tok/s

Estimated speed at Q4_K_M (3.0 GB)

~988 tok/s
~222 tok/s
~739 tok/s
~611 tok/s

Real-world results typically within ±20%. Speed depends on batch size, quantization kernel, and software stack.

Learn more about tok/s estimation →

What's the download size of Phi 4 Mini Flash Reasoning?

At Q4_K_M, the download is about 2.31 GB. The full-precision Q8_0 version is 3.85 GB. The smallest option (Q2_K) is 1.64 GB.

Which GPUs can run Phi 4 Mini Flash Reasoning?

35 consumer GPUs can run Phi 4 Mini Flash Reasoning at Q4_K_M (3.0 GB). Top options include AMD Radeon RX 6700 XT, AMD Radeon RX 6800, AMD Radeon RX 6800 XT. 35 GPUs have plenty of headroom for comfortable inference.

Which devices can run Phi 4 Mini Flash Reasoning?

33 devices with unified memory can run Phi 4 Mini Flash Reasoning at Q4_K_M (3.0 GB), including Mac Mini M4 (16 GB), Mac Mini M4 (32 GB), Mac Mini M4 Pro (24 GB), Mac Mini M4 Pro (48 GB). Apple Silicon Macs use unified memory shared between CPU and GPU, making them well-suited for local LLM inference.