API cost decision in 10 seconds

Devstral 2 2512 vs GPT-5.1-Codex

Pick Devstral 2 2512 for lower cost; pick GPT-5.1-Codex only if the larger context window matters more.

Page updated:  Data confirmed:  Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Devstral 2 2512 for lower cost; pick GPT-5.1-Codex only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Devstral 2 2512 is estimated at $1.4 vs $6.25 for GPT-5.1-Codex, saving $4.85 (77.6% lower).

Cost-first pickDevstral 2 2512
Context-first pickGPT-5.1-Codex
Sample savings$4.8577.6%
10x traffic gap$48.5

GPT-5.1-Codex has more context, but Devstral 2 2512 saves $4.85 on the standard workload. At 10x that traffic, the same price gap is about $48.5. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Devstral 2 2512 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shapeToken mixBetter pickDevstral 2 2512GPT-5.1-Codex
Input-heavy / RAG5M input + 500K outputDevstral 2 2512$3$11.25
Balanced workload1M input + 1M outputDevstral 2 2512$2.4$11.25
Output-heavy chatbot1M input + 5M outputDevstral 2 2512$10.4$51.25
Cheaper input Devstral 2 2512 $0.4 vs $1.25 / 1M

Devstral 2 2512 is $0.85 cheaper per 1M input tokens (68% lower; 3.12x difference).

Cheaper output Devstral 2 2512 $2 vs $10 / 1M

Devstral 2 2512 is $8 cheaper per 1M output tokens (80% lower; 5x difference).

Larger context GPT-5.1-Codex 262.14K vs 400K

GPT-5.1-Codex has 137.86K more context (1.53x larger).

Sample workload Devstral 2 2512 $1.4 vs $6.25

Devstral 2 2512 is $4.85 cheaper on the standard workload (77.6% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
Devstral 2 2512 Calculating… Estimated API cost
GPT-5.1-Codex Calculating… Estimated API cost
Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

Devstral 2 2512 has the lower input price; Devstral 2 2512 has the lower output price; GPT-5.1-Codex offers the larger context window. For the 1M input plus 500K output sample, Devstral 2 2512 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $1.4 for Devstral 2 2512 and $6.25 for GPT-5.1-Codex.

Best Fit

Choose Devstral 2 2512 when you care most about lower input-token price, and lower output-token price.

Choose GPT-5.1-Codex when you care most about larger context window.

Decision Notes
  • On the standard 1M input plus 500K output workload, Devstral 2 2512 is estimated at $1.4 vs $6.25 for GPT-5.1-Codex, saving $4.85 (77.6% lower).
  • Devstral 2 2512 is $4.85 cheaper on the standard workload (77.6% lower).
  • Devstral 2 2512 is $0.85 cheaper per 1M input tokens (68% lower; 3.12x difference).
  • Devstral 2 2512 is $8 cheaper per 1M output tokens (80% lower; 5x difference).
  • GPT-5.1-Codex has 137.86K more context (1.53x larger).
Head-to-Head Specs
FeatureDevstral 2 2512
(Mistral)		GPT-5.1-Codex
(OpenAI)
Input Price
prompt tokens per 1M		$0.4$1.25
Completion Price
per 1M tokens		$2$10
Sample Workload Cost
1M input + 500K output		$1.4$6.25
Context Window262.14K400K
Release Date

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionDevstral 2 2512On the standard 1M input plus 500K output workload, Devstral 2 2512 is estimated at $1.4 vs $6.25 for GPT-5.1-Codex, saving $4.85 (77.6% lower).
High-volume input processingDevstral 2 2512Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsDevstral 2 2512Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document workGPT-5.1-CodexA larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps
  • Mistral Nemo can replace Devstral 2 2512 when lower sample workload cost matters most: $0.04.
  • Mistral Small 3 can replace Devstral 2 2512 when lower sample workload cost matters most: $0.09.
  • Ministral 3 3B 2512 can replace Devstral 2 2512 when lower sample workload cost matters most: $0.15.
  • Mistral Small 3.2 24B can replace Devstral 2 2512 when lower sample workload cost matters most: $0.17.
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Devstral 2 2512

Devstral 2 is a state-of-the-art open-source model by Mistral AI specializing in agentic coding. It is a 123B-parameter dense transformer model supporting a 256K context window. Devstral 2 supports exploring...

GPT-5.1-Codex

GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....