Kimi K2 0905 is $1.4 cheaper per 1M input tokens (70% lower; 3.33x difference).
API cost decision in 10 seconds
Kimi K2 0905 vs Gemini 3.1 Pro Preview Custom Tools
Pick Kimi K2 0905 for lower cost; pick Gemini 3.1 Pro Preview Custom Tools 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 Gemini 3.1 Pro Preview Custom Tools 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 for Gemini 3.1 Pro Preview Custom Tools, saving $6.15 (76.9% lower).
Cost-first pickKimi K2 0905
Context-first pickGemini 3.1 Pro Preview Custom Tools
Sample savings$6.1576.9%
10x traffic gap$61.5
Gemini 3.1 Pro Preview Custom Tools has more context, but Kimi K2 0905 saves $6.15 on the standard workload. At 10x that traffic, the same price gap is about $61.5. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
Kimi K2 0905 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | Kimi K2 0905 | Gemini 3.1 Pro Preview Custom Tools |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | Kimi K2 0905 | $4.25 | $16 |
| Balanced workload | 1M input + 1M output | Kimi K2 0905 | $3.1 | $14 |
| Output-heavy chatbot | 1M input + 5M output | Kimi K2 0905 | $13.1 | $62 |
Kimi K2 0905 is $9.5 cheaper per 1M output tokens (79.2% lower; 4.8x difference).
Gemini 3.1 Pro Preview Custom Tools has 786.61K more context (4x larger).
Kimi K2 0905 is $6.15 cheaper on the standard workload (76.9% lower).
Estimate your workload cost
Your Workload Cost
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
Kimi K2 0905 has the lower input price; Kimi K2 0905 has the lower output price; Gemini 3.1 Pro Preview Custom Tools 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 $1.85 for Kimi K2 0905 and $8 for Gemini 3.1 Pro Preview Custom Tools.
Choose Kimi K2 0905 when you care most about lower input-token price, and lower output-token price.
Choose Gemini 3.1 Pro Preview Custom Tools when you care most about larger context window.
- On the standard 1M input plus 500K output workload, Kimi K2 0905 is estimated at $1.85 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6.15 (76.9% lower).
- Kimi K2 0905 is $6.15 cheaper on the standard workload (76.9% lower).
- Kimi K2 0905 is $1.4 cheaper per 1M input tokens (70% lower; 3.33x difference).
- Kimi K2 0905 is $9.5 cheaper per 1M output tokens (79.2% lower; 4.8x difference).
- Gemini 3.1 Pro Preview Custom Tools has 786.61K more context (4x larger).
| Feature | Kimi K2 0905 (MoonshotAI) | Gemini 3.1 Pro Preview Custom Tools (Google) |
|---|---|---|
| Input Price prompt tokens per 1M | $0.6 | $2 |
| Completion Price per 1M tokens | $2.5 | $12 |
| Sample Workload Cost 1M input + 500K output | $1.85 | $8 |
| Context Window | 262.14K | 1.05M |
| Release Date | ||
| Popularity | #70 | #132 |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | Kimi K2 0905 | On the standard 1M input plus 500K output workload, Kimi K2 0905 is estimated at $1.85 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6.15 (76.9% lower). |
| High-volume input processing | Kimi K2 0905 | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | Kimi K2 0905 | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | Gemini 3.1 Pro Preview Custom Tools | A larger context window leaves more room for retrieved passages, conversation history, or source files. |
Related Alternatives
- 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.
- Gemma 4 31B (free) can replace Gemini 3.1 Pro Preview Custom Tools when lower sample workload cost matters most: $0.
- Gemma 4 26B A4B (free) can replace Gemini 3.1 Pro Preview Custom Tools when lower sample workload cost matters most: $0.
- 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.
- DeepSeek V4 Flash · DeepSeek · #1
- Hy3 preview · Tencent · #2
- Claude Opus 4.7 · Anthropic · #3
- Claude Sonnet 4.6 · Anthropic · #4
Cheaper alternatives
Review low-cost models sorted by a standard 1M input plus 500K output workload.
Open cheapest modelsLarger context alternatives
Find models with larger context windows for RAG, long documents, and codebase review.
Open largest context modelsProvider catalogs
Compare models within provider hubs before choosing a final API vendor.
Open provider hubsMoonshotAI catalog
Review all tracked MoonshotAI models before deciding whether this matchup is the right shortlist.
Open MoonshotAI modelsGoogle catalog
Check other Google models with comparable pricing, context, or release timing.
Open Google modelsKimi 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...
Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party...