API cost decision in 10 seconds

GPT-5.3-Codex vs Kimi K2 0905

Pick Kimi K2 0905 for lower cost; pick GPT-5.3-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 Kimi K2 0905 for lower cost; pick GPT-5.3-Codex only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Kimi K2 0905 is estimated at $1.85 vs $8.75 for GPT-5.3-Codex, saving $6.9 (78.9% lower).

Cost-first pickKimi K2 0905
Context-first pickGPT-5.3-Codex
Sample savings$6.978.9%
10x traffic gap$69

GPT-5.3-Codex has more context, but Kimi K2 0905 saves $6.9 on the standard workload. At 10x that traffic, the same price gap is about $69. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Kimi K2 0905 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shapeToken mixBetter pickGPT-5.3-CodexKimi K2 0905
Input-heavy / RAG5M input + 500K outputKimi K2 0905$15.75$4.25
Balanced workload1M input + 1M outputKimi K2 0905$15.75$3.1
Output-heavy chatbot1M input + 5M outputKimi K2 0905$71.75$13.1
Cheaper input Kimi K2 0905 $1.75 vs $0.6 / 1M

Kimi K2 0905 is $1.15 cheaper per 1M input tokens (65.7% lower; 2.92x difference).

Cheaper output Kimi K2 0905 $14 vs $2.5 / 1M

Kimi K2 0905 is $11.5 cheaper per 1M output tokens (82.1% lower; 5.6x difference).

Larger context GPT-5.3-Codex 400K vs 262.14K

GPT-5.3-Codex has 137.86K more context (1.53x larger).

Sample workload Kimi K2 0905 $8.75 vs $1.85

Kimi K2 0905 is $6.9 cheaper on the standard workload (78.9% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.
GPT-5.3-Codex Calculating… Estimated API cost
Kimi K2 0905 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

Kimi K2 0905 has the lower input price; Kimi K2 0905 has the lower output price; GPT-5.3-Codex offers the larger context window. For the 1M input plus 500K output sample, Kimi K2 0905 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $8.75 for GPT-5.3-Codex and $1.85 for Kimi K2 0905.

Best Fit

Choose GPT-5.3-Codex when you care most about larger context window.

Choose Kimi K2 0905 when you care most about lower input-token price, and lower output-token price.

Decision Notes
  • On the standard 1M input plus 500K output workload, Kimi K2 0905 is estimated at $1.85 vs $8.75 for GPT-5.3-Codex, saving $6.9 (78.9% lower).
  • Kimi K2 0905 is $6.9 cheaper on the standard workload (78.9% lower).
  • Kimi K2 0905 is $1.15 cheaper per 1M input tokens (65.7% lower; 2.92x difference).
  • Kimi K2 0905 is $11.5 cheaper per 1M output tokens (82.1% lower; 5.6x difference).
  • GPT-5.3-Codex has 137.86K more context (1.53x larger).
Head-to-Head Specs
FeatureGPT-5.3-Codex
(OpenAI)		Kimi K2 0905
(MoonshotAI)
Input Price
prompt tokens per 1M		$1.75$0.6
Completion Price
per 1M tokens		$14$2.5
Sample Workload Cost
1M input + 500K output		$8.75$1.85
Context Window400K262.14K
Release Date
Popularity#44#70

Use-Case Decision Matrix

Use caseBetter pickWhy
Budget-constrained productionKimi K2 0905On the standard 1M input plus 500K output workload, Kimi K2 0905 is estimated at $1.85 vs $8.75 for GPT-5.3-Codex, saving $6.9 (78.9% lower).
High-volume input processingKimi K2 0905Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbotsKimi K2 0905Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document workGPT-5.3-CodexA larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps
  • gpt-oss-120b (free) can replace GPT-5.3-Codex when lower sample workload cost matters most: $0.
  • gpt-oss-20b (free) can replace GPT-5.3-Codex when lower sample workload cost matters most: $0.
  • gpt-oss-20b can replace GPT-5.3-Codex when lower sample workload cost matters most: $0.1.
  • gpt-oss-120b can replace GPT-5.3-Codex when lower sample workload cost matters most: $0.13.
Larger context near this budget
  • Llama 4 Scout offers 10M context with $0.23 sample workload cost.
  • Grok 4.20 offers 2M context with $2.5 sample workload cost.
  • Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
  • GPT-5.4 offers 1.05M context with $10 sample workload cost.

Cheaper alternatives

Review low-cost models sorted by a standard 1M input plus 500K output workload.

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Larger context alternatives

Find models with larger context windows for RAG, long documents, and codebase review.

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Provider catalogs

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OpenAI catalog

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MoonshotAI catalog

Check other MoonshotAI models with comparable pricing, context, or release timing.

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GPT-5.3-Codex

GPT-5.3-Codex is OpenAI’s most advanced agentic coding model, combining the frontier software engineering performance of GPT-5.2-Codex with the broader reasoning and professional knowledge capabilities of GPT-5.2. It achieves state-of-the-art results...

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...