Llama 3.1 405B Instruct vs Mistral Magistral Small 2509
Llama 3.1 405B Instruct (2024) and Mistral Magistral Small 2509 (2025) are compact production models from AI at Meta and MistralAI. Llama 3.1 405B Instruct ships a 128k-token context window, while Mistral Magistral Small 2509 ships a not-yet-sourced context window. On pricing, Mistral Magistral Small 2509 costs $0.50/1M input tokens versus $2.40/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Mistral Magistral Small 2509 is ~380% cheaper at $0.50/1M; pay for Llama 3.1 405B Instruct only for provider fit.
Decision scorecard
Local evidence first| Signal | Llama 3.1 405B Instruct | Mistral Magistral Small 2509 |
|---|---|---|
| Best for | provider-routed production | provider-routed production |
| Decision fit | RAG, Long context, and Classification | General |
| Context window | 128k | — |
| Cheapest output | $2.40/1M tokens | $1.50/1M tokens |
| Provider routes | 11 tracked | 2 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Llama 3.1 405B Instruct has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Llama 3.1 405B Instruct has broader tracked provider coverage for fallback and procurement flexibility.
- Llama 3.1 405B Instruct uniquely exposes Structured outputs in local model data.
- Local decision data tags Llama 3.1 405B Instruct for RAG, Long context, and Classification.
- Mistral Magistral Small 2509 has the lower cheapest tracked output price at $1.50/1M tokens.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Llama 3.1 405B Instruct
$2,520
Cheapest tracked route/tier: AWS Bedrock
Mistral Magistral Small 2509
$775
Cheapest tracked route/tier: AWS Bedrock
Estimated monthly gap: $1,745. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on AWS Bedrock; start route-level A/B tests there.
- Mistral Magistral Small 2509 is $0.90/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Structured outputs before moving production traffic.
- Provider overlap exists on AWS Bedrock; start route-level A/B tests there.
- Llama 3.1 405B Instruct is $0.90/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Llama 3.1 405B Instruct adds Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2024-07-23 | 2025-09-01 |
| Context window | 128k | — |
| Parameters | 405B | 24B |
| Architecture | decoder only | - |
| License | Llama 3 Community | Apache 2.0(OSI) |
| Openness | Open weights | Open source |
| Commercial use | Commercial use with conditions | Commercial use allowed |
| Knowledge cutoff | 2023-12 | - |
Pricing and availability
| Pricing attribute | Llama 3.1 405B Instruct | Mistral Magistral Small 2509 |
|---|---|---|
| Input price | $2.40/1M tokens | $0.50/1M tokens |
| Output price | $2.40/1M tokens | $1.50/1M tokens |
| Providers |
Capabilities
| Capability | Llama 3.1 405B Instruct | Mistral Magistral Small 2509 |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | No | No |
| Function calling | No | No |
| Tool use | No | No |
| Structured outputs | Yes | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on structured outputs: Llama 3.1 405B Instruct. Both models share the core language-model surface, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Llama 3.1 405B Instruct lists $2.40/1M input and $2.40/1M output tokens on the cheapest tracked provider, while Mistral Magistral Small 2509 lists $0.50/1M input and $1.50/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Mistral Magistral Small 2509 lower by about $1.60 per million blended tokens. Availability is 11 providers versus 2, so concentration risk also matters.
Choose Llama 3.1 405B Instruct when provider fit and broader provider choice are central to the workload. Choose Mistral Magistral Small 2509 when provider fit and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which is cheaper, Llama 3.1 405B Instruct or Mistral Magistral Small 2509?
Mistral Magistral Small 2509 is cheaper on tracked token pricing. Llama 3.1 405B Instruct costs $2.40/1M input and $2.40/1M output tokens. Mistral Magistral Small 2509 costs $0.50/1M input and $1.50/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Llama 3.1 405B Instruct or Mistral Magistral Small 2509 open source?
Llama 3.1 405B Instruct is listed under Llama 3 Community. Mistral Magistral Small 2509 is listed under Apache 2.0. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for structured outputs, Llama 3.1 405B Instruct or Mistral Magistral Small 2509?
Llama 3.1 405B Instruct has the clearer documented structured outputs signal in this comparison. If structured outputs is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Llama 3.1 405B Instruct and Mistral Magistral Small 2509?
Llama 3.1 405B Instruct is available on OctoAI API (Deprecated), Together AI, Fireworks AI, IBM watsonx, and Scale AI GenAI Platform. Mistral Magistral Small 2509 is available on AWS Bedrock and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
When should I pick Llama 3.1 405B Instruct over Mistral Magistral Small 2509?
Mistral Magistral Small 2509 is ~380% cheaper at $0.50/1M; pay for Llama 3.1 405B Instruct only for provider fit. If your workload also depends on provider fit, start with Llama 3.1 405B Instruct; if it depends on provider fit, run the same evaluation with Mistral Magistral Small 2509.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.