VRAM Requirements for Phi-3 Medium

How much VRAM does Phi-3 Medium actually need?

Running large language models like Phi-3 Medium locally in 2026 requires precise memory calculation. Our professional formula accounts for model weights, KV cache, context length, and the CUDA overhead necessary to run inference without hitting Out of Memory (OOM) errors.

The VRAM Formula (2026)

VRAM = (Parameters * bits / 8) * 1.2 + 1.5

This formula applies a 1.2x multiplier for system activations and a 1.5GB static base for the context window KV Cache, which is the enterprise standard for deploying Phi-3 Medium.

Best GPUs for Phi-3 Medium

If Phi-3 Medium requires under 24GB, the RTX 3090 or RTX 4090 are the undisputed kings for cost-performance. If it crosses 40GB or 80GB, you must look into dual-GPU builds or enterprise A100/H100 clusters.