Phi-4-mini (3.8B) RAM Calculator
Microsoft's lightweight reasoning marvel. Packed with high-density intelligence for fast local text processing and on-device execution.
16GB RAM
Calculated for 4-bit (Q4_K_M) @ 8K Context1. Select Quantization Level
Quantization compresses model weights to reduce RAM usage, with minor impacts on output quality.
2. Set Target Context Length
Longer contexts require more active memory for the Key-Value (KV) cache.
Inference Bandwidth & Speed Matrix
Estimates generation speeds (tokens per second) based on physical memory channel bandwidth constraints.
DDR4 CPU Mode
45 GB/s
21.4 t/s
DDR5 CPU Mode
96 GB/s
45.7 t/s
Mac Unified Memory
300 GB/s
142.9 t/s
GPU VRAM (RTX 4090)
1008 GB/s
480.0 t/s
*Token throughput calculated strictly from weight volume transfers over memory channels. Actual generation speeds can be further throttled by processing threads or VRAM offloading parameters.
16GB System RAM
Stably runs model with Q4/Q8/FP16 quantization & target context windows.
Memory Allocation Sizer
Dynamic Dual-Channel Picks (16GB)
Silicon Power DDR4 16GB 3200MHz (PC4-25600) CL22 SODIMM 260-Pin 1.2V Non-ECC Laptop RAM Notebook Computer Memory SU016GBSFU320F02AB
A-Tech 16GB (2x8GB) DDR4 2133 MHz SODIMM PC4-17000 (PC4-2133P) CL15 Non-ECC Laptop RAM Memory Modules
A-Tech 16GB DDR4 2133 MHz SODIMM PC4-17000 (PC4-2133P) CL15 2Rx8 Non-ECC Laptop RAM Memory Module
Z1 DDR4 3200MHz (PC4 25600) 16GB (2x8GB) 288-Pin CL16-20-20 Memory Modules, Silver (AX4U320038G16A-DSZ1)
Technical Specifications
GPU & VRAM Sizing Profile
Budget / Entry GPUHardware Profile: Excellent for lightweight dense or edge models. Fits completely inside budget GPU VRAM for maximum processing speeds.
Phi-4-mini (3.8B) Memory FAQs
How much RAM does Phi-4-mini (3.8B) require?
To run Phi-4-mini (3.8B) locally, memory size depends on your selected quantization. At 4-bit compression (Q4_K_M), the weights take up ~2.1GB of RAM. When combined with context cache and OS overhead, a standard **16GB system memory kit** is recommended. Unquantized FP16 execution requires a **16GB memory setup**.
What are the hardware requirements to run Phi-4-mini (3.8B) at FP16 precision?
Running Phi-4-mini (3.8B) at unquantized 16-bit precision requires loading ~7.6GB of model weights directly into VRAM or system memory. A minimum system memory target of **16GB RAM** is required to run the weights stably and avoid out-of-memory crashes.
Is Phi-4-mini (3.8B) dense or Mixture-of-Experts (MoE)?
Phi-4-mini (3.8B) is built on a **Dense** architecture. It features a dense parameter layout containing 3.8 Billion parameters. All weights are active and computed on every single pass during token generation.
How does context window size affect RAM usage for Phi-4-mini (3.8B)?
Context size directly scales the size of the Key-Value (KV) cache. At a standard 8,192 token context, the KV cache for Phi-4-mini (3.8B) uses ~0.01GB. If you scale this to 128K tokens, the KV cache can scale past hundreds of GBs, requiring multi-GPU or workstation-class RAM configurations.