Microsoft
Phi 3.5 (3.8B)
Efficient model used for mobile and constrained environments
Model Summary
Family
Phi
Version
3.5
Parameters
3.8B (est.)
Parameter counts for closed models are estimates; vendors rarely publish exact sizes.
VRAM Requirements by Quantization
Memory needed to serve Phi 3.5 (3.8B) for inference, including a 20% overhead for activations and KV cache.
| Precision | VRAM needed | Smallest single GPU that fits |
|---|---|---|
| INT4 (4-bit) | 2.12 GB | NVIDIA P100 SXM2 (16 GB) |
| INT8 (8-bit) | 4.25 GB | NVIDIA P100 SXM2 (16 GB) |
| FP16 (16-bit) | 8.49 GB | NVIDIA P100 SXM2 (16 GB) |
| FP32 (32-bit) | 16.99 GB | NVIDIA L4 (24 GB) |
Recommended GPU Configurations
Cheapest on-demand configurations to serve Phi 3.5 (3.8B) at 8-bit (4 GB VRAM).
1x NVIDIA T4
16 GB total VRAM · Turing
~$0.50/h
1x NVIDIA P100 SXM2
16 GB total VRAM · Pascal
~$0.60/h
1x NVIDIA L4
24 GB total VRAM · Ada Lovelace
~$1.00/h
Quick GPU Planning
Use the calculator pre-filled with this exact version to estimate memory, speed, and compute requirements in a few clicks.
Access Pre-filled CalculatorFrequently Asked Questions
How much VRAM do you need to run Phi 3.5 (3.8B)?
With an estimated 3.8B parameters, Phi 3.5 (3.8B) needs roughly 4 GB of VRAM in 8-bit (INT8), 2 GB in 4-bit, and 8 GB in FP16, including a 20% overhead for activations and KV cache.
Which GPUs can run Phi 3.5 (3.8B)?
At 8-bit quantization, the most cost-effective option is 1x NVIDIA T4 (16 GB combined VRAM, around $0.50/hour on-demand). Higher-end cards like the NVIDIA B200 or AMD MI355X reduce the GPU count needed.
Can Phi 3.5 (3.8B) run on a single GPU?
Yes. In 8-bit, a single NVIDIA P100 SXM2 (16 GB) fits the model.
How much does it cost to serve Phi 3.5 (3.8B) in the cloud?
Renting 1x T4 costs on the order of $0.50/hour, i.e. about $365/month running 24/7. Actual prices vary by provider and commitment; spot and reserved capacity can be significantly cheaper.
Deploy on a GPU cloud
Rent 1x T4 by the hour instead of buying hardware.
