API cost decision in 10 seconds

Kimi K2 0905 vs GPT-5.1-Codex-Mini

Pick GPT-5.1-Codex-Mini when budget and context both matter.

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

Budget verdict

Pick GPT-5.1-Codex-Mini when budget and context both matter.

On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Mini is estimated at $1.25 vs $1.85 for Kimi K2 0905, saving $0.6 (32.4% lower).

Cost-first pickGPT-5.1-Codex-Mini
Context-first pickGPT-5.1-Codex-Mini
Sample savings$0.632.4%
10x traffic gap$6

GPT-5.1-Codex-Mini is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $6. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GPT-5.1-Codex-Mini stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shapeToken mixBetter pickKimi K2 0905GPT-5.1-Codex-Mini
Input-heavy / RAG5M input + 500K outputGPT-5.1-Codex-Mini$4.25$2.25
Balanced workload1M input + 1M outputGPT-5.1-Codex-Mini$3.1$2.25
Output-heavy chatbot1M input + 5M outputGPT-5.1-Codex-Mini$13.1$10.25
Cheaper input GPT-5.1-Codex-Mini $0.6 vs $0.25 / 1M

GPT-5.1-Codex-Mini is $0.35 cheaper per 1M input tokens (58.3% lower; 2.4x difference).

Cheaper output GPT-5.1-Codex-Mini $2.5 vs $2 / 1M

GPT-5.1-Codex-Mini is $0.5 cheaper per 1M output tokens (20% lower; 1.25x difference).

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

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

Sample workload GPT-5.1-Codex-Mini $1.85 vs $1.25

GPT-5.1-Codex-Mini is $0.6 cheaper on the standard workload (32.4% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
Kimi K2 0905 Calculating… Estimated API cost
GPT-5.1-Codex-Mini 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

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

For a 1M input token plus 500K output token workload, the estimated API cost is $1.85 for Kimi K2 0905 and $1.25 for GPT-5.1-Codex-Mini.

Best Fit

Choose Kimi K2 0905 when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Choose GPT-5.1-Codex-Mini when you care most about lower input-token price, lower output-token price, and larger context window.

Decision Notes
  • On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Mini is estimated at $1.25 vs $1.85 for Kimi K2 0905, saving $0.6 (32.4% lower).
  • GPT-5.1-Codex-Mini is $0.6 cheaper on the standard workload (32.4% lower).
  • GPT-5.1-Codex-Mini is $0.35 cheaper per 1M input tokens (58.3% lower; 2.4x difference).
  • GPT-5.1-Codex-Mini is $0.5 cheaper per 1M output tokens (20% lower; 1.25x difference).
  • GPT-5.1-Codex-Mini has 137.86K more context (1.53x larger).
Head-to-Head Specs
FeatureKimi K2 0905
(MoonshotAI)		GPT-5.1-Codex-Mini
(OpenAI)
Input Price
prompt tokens per 1M		$0.6$0.25
Completion Price
per 1M tokens		$2.5$2
Sample Workload Cost
1M input + 500K output		$1.85$1.25
Context Window262.14K400K
Release Date
Popularity#70#141

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionGPT-5.1-Codex-MiniOn the standard 1M input plus 500K output workload, GPT-5.1-Codex-Mini is estimated at $1.25 vs $1.85 for Kimi K2 0905, saving $0.6 (32.4% lower).
High-volume input processingGPT-5.1-Codex-MiniLower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsGPT-5.1-Codex-MiniLower output-token price matters most when assistants generate many completion tokens.
RAG or long-document workGPT-5.1-Codex-MiniA larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps
  • Kimi K2.5 can replace Kimi K2 0905 when lower sample workload cost matters most: $1.35.
  • Kimi K2 0711 can replace Kimi K2 0905 when lower sample workload cost matters most: $1.72.
  • gpt-oss-120b (free) can replace GPT-5.1-Codex-Mini when lower sample workload cost matters most: $0.
  • gpt-oss-20b (free) can replace GPT-5.1-Codex-Mini when lower sample workload cost matters most: $0.
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Kimi K2 0905

Kimi K2 0905 is the September update of [Kimi K2 0711](moonshotai/kimi-k2). It is a large-scale Mixture-of-Experts (MoE) language model developed by Moonshot AI, featuring 1 trillion total parameters with 32...

GPT-5.1-Codex-Mini

GPT-5.1-Codex-Mini is a smaller and faster version of GPT-5.1-Codex