Llama 3.1 405B vs Phi-4
Architecture Comparison
SpecLlama 3.1 405BPhi-4
TypeDENSEDENSE
Total Parameters405B14.7B
Active Parameters405B14.7B
Layers12640
Hidden Dimension16,3845,120
Attention Heads12840
KV Heads810
Context Length131,07216,384
Precision (default)BF16BF16
Memory Requirements
PrecisionLlama 3.1 405BPhi-4
BF16 Weights810.0 GB29.4 GB
FP8 Weights405.0 GB14.7 GB
INT4 Weights202.5 GB7.3 GB
KV-Cache / Token516096 B204800 B
Activation Estimate5.00 GB1.50 GB
Minimum GPUs Needed (BF16)
H100 SXMN/A1 GPU
L40SN/A1 GPU
Quality Benchmarks
BenchmarkLlama 3.1 405BPhi-4
Overall8883
MMLU88.684.8
HumanEval61.067.0
GSM8K96.893.0
MT-Bench88.085.0
Llama 3.1 405B
MMLU
88.6
HumanEval
61.0
GSM8K
96.8
MT-Bench
88.0
Phi-4
MMLU
84.8
HumanEval
67.0
GSM8K
93.0
MT-Bench
85.0
Capabilities
FeatureLlama 3.1 405BPhi-4
Tool Use✓ Yes✓ Yes
Vision✗ No✗ No
Code✓ Yes✓ Yes
Math✓ Yes✓ Yes
Reasoning✗ No✓ Yes
Multilingual✓ Yes✓ Yes
Structured Output✓ Yes✓ Yes
API Pricing Comparison
Cheapest Output (Llama 3.1 405B)
$3.00/M
Input: $3.00/M
Cheapest Output (Phi-4)
$0.14/M
Input: $0.07/M
| Provider | Llama 3.1 405B In $/M | Out $/M | Phi-4 In $/M | Out $/M |
|---|---|---|---|---|
| azure | — | — | $0.07 | $0.14 |
| together | $3.50 | $3.50 | $0.20 | $0.20 |
| fireworks | $3.00 | $3.00 | — | — |
Recommendation Summary
- ‣Llama 3.1 405B scores higher on overall quality (88 vs 83).
- ‣Phi-4 is cheaper per output token ($0.14/M vs $3.00/M).
- ‣Phi-4 has a smaller memory footprint (29.4 GB vs 810.0 GB BF16), making it easier to deploy on fewer GPUs.
- ‣Llama 3.1 405B supports a longer context window (131,072 vs 16,384 tokens).
- ‣Phi-4 is stronger at code generation (HumanEval: 67.0 vs 61.0).
- ‣Llama 3.1 405B is better at math reasoning (GSM8K: 96.8 vs 93.0).