Llama 3.1 405B vs Phi-3 Mini 128K
Llama 3.1 405B (2024) and Phi-3 Mini 128K (2024) are compact production models from AI at Meta and Microsoft Research. Llama 3.1 405B ships a 128K-token context window, while Phi-3 Mini 128K ships a 128K-token context window. On Google-Proof Q&A, Llama 3.1 405B leads by a hair. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Llama 3.1 405B is safer overall; choose Phi-3 Mini 128K when provider fit matters.
Decision scorecard
Local evidence first| Signal | Llama 3.1 405B | Phi-3 Mini 128K |
|---|---|---|
| Decision fit | Coding, Long context, and Classification | Coding, Long context, and Classification |
| Context window | 128K | 128K |
| Cheapest output | - | $0.25/1M tokens |
| Provider routes | 0 tracked | 5 tracked |
| Shared benchmarks | Google-Proof Q&A leader | 4 rows |
Decision tradeoffs
- Llama 3.1 405B leads the largest shared benchmark signal on Google-Proof Q&A by 0.7 points.
- Local decision data tags Llama 3.1 405B for Coding, Long context, and Classification.
- Phi-3 Mini 128K has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Phi-3 Mini 128K for Coding, Long context, and Classification.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Llama 3.1 405B
Unavailable
No complete token price in local provider data
Phi-3 Mini 128K
$103
Cheapest tracked route: Replicate API
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Llama 3.1 405B and Phi-3 Mini 128K; plan for SDK, billing, or endpoint changes.
- No overlapping tracked provider route is sourced for Phi-3 Mini 128K and Llama 3.1 405B; plan for SDK, billing, or endpoint changes.
Specs
| Specification | ||
|---|---|---|
| Released | 2024-07-23 | 2024-04-23 |
| Context window | 128K | 128K |
| Parameters | 405B | 3.8B |
| Architecture | decoder only | decoder only |
| License | Open Source | Open Source |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Llama 3.1 405B | Phi-3 Mini 128K |
|---|---|---|
| Input price | - | $0.05/1M tokens |
| Output price | - | $0.25/1M tokens |
| Providers | - |
Capabilities
| Capability | Llama 3.1 405B | Phi-3 Mini 128K |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | No | No |
| Function calling | No | No |
| Tool use | No | No |
| Structured outputs | No | No |
| Code execution | No | No |
Benchmarks
| Benchmark | Llama 3.1 405B | Phi-3 Mini 128K |
|---|---|---|
| Google-Proof Q&A | 51.5 | 50.8 |
| HumanEval | 89.0 | 75.9 |
| Massive Multitask Language Understanding | 88.6 | 76.5 |
| HellaSwag | 95.8 | 90.2 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Llama 3.1 405B at 51.5 and Phi-3 Mini 128K at 50.8, with Llama 3.1 405B ahead by 0.7 points; HumanEval has Llama 3.1 405B at 89 and Phi-3 Mini 128K at 75.9, with Llama 3.1 405B ahead by 13.1 points; Massive Multitask Language Understanding has Llama 3.1 405B at 88.6 and Phi-3 Mini 128K at 76.5, with Llama 3.1 405B ahead by 12.1 points. The largest visible gap is 13.1 points on HumanEval, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint is close: both models cover the core production surface. That makes context budget, benchmark fit, and provider maturity more important than a simple checklist. If your application depends on one integration detail, verify it against the provider route you plan to use, not just the base model listing.
Pricing coverage is uneven: Llama 3.1 405B has no token price sourced yet and Phi-3 Mini 128K has $0.05/1M input tokens. Provider availability is 0 tracked routes versus 5. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Llama 3.1 405B when provider fit are central to the workload. Choose Phi-3 Mini 128K when provider fit and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Llama 3.1 405B or Phi-3 Mini 128K?
Llama 3.1 405B supports 128K tokens, while Phi-3 Mini 128K supports 128K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Llama 3.1 405B or Phi-3 Mini 128K open source?
Llama 3.1 405B is listed under Open Source. Phi-3 Mini 128K is listed under Open Source. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Where can I run Llama 3.1 405B and Phi-3 Mini 128K?
Llama 3.1 405B is available on the tracked providers still being sourced. Phi-3 Mini 128K is available on NVIDIA NIM, Baseten API, Microsoft Foundry, Fireworks AI, and Replicate API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
When should I pick Llama 3.1 405B over Phi-3 Mini 128K?
Llama 3.1 405B is safer overall; choose Phi-3 Mini 128K when provider fit matters. If your workload also depends on provider fit, start with Llama 3.1 405B; if it depends on provider fit, run the same evaluation with Phi-3 Mini 128K.
Continue comparing
Last reviewed: 2026-05-01. Data sourced from public model cards and provider documentation.