Union Alpha is free for input tokens while Kimi K3 (batch) costs $3 per 1M tokens.
API cost decision in 10 seconds
NewUnion Alpha vs Kimi K3 (batch)
Pick Union Alpha for lower cost; pick Kimi K3 (batch) 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 Union Alpha for lower cost; pick Kimi K3 (batch) only if the larger context window matters more.
On the standard 1M input plus 500K output workload, Union Alpha is estimated at $0 vs $10.5 for Kimi K3 (batch), saving $10.5 (100% lower).
Cost-first pickUnion Alpha
Context-first pickKimi K3 (batch)
Sample savings$10.5100%
10x traffic gap$105
Kimi K3 (batch) has more context, but Union Alpha saves $10.5 on the standard workload. At 10x that traffic, the same price gap is about $105. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
Union Alpha stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | Union Alpha | Kimi K3 (batch) |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | Union Alpha | $0 | $22.5 |
| Balanced workload | 1M input + 1M output | Union Alpha | $0 | $18 |
| Output-heavy chatbot | 1M input + 5M output | Union Alpha | $0 | $78 |
Union Alpha is free for output tokens while Kimi K3 (batch) costs $15 per 1M tokens.
Kimi K3 (batch) has 786.43K more context (4x larger).
Union Alpha is free for the standard workload while the other model is estimated at $10.5.
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
Union Alpha has the lower input price; Union Alpha has the lower output price; Kimi K3 (batch) offers the larger context window. For the 1M input plus 500K output sample, Union Alpha is cheaper for the standard workload.
For a 1M input token plus 500K output token workload, the estimated API cost is $0 for Union Alpha and $10.5 for Kimi K3 (batch).
Choose Union Alpha when you care most about lower input-token price, and lower output-token price.
Choose Kimi K3 (batch) when you care most about larger context window.
- On the standard 1M input plus 500K output workload, Union Alpha is estimated at $0 vs $10.5 for Kimi K3 (batch), saving $10.5 (100% lower).
- Union Alpha is free for the standard workload while the other model is estimated at $10.5.
- Union Alpha is free for input tokens while Kimi K3 (batch) costs $3 per 1M tokens.
- Union Alpha is free for output tokens while Kimi K3 (batch) costs $15 per 1M tokens.
- Kimi K3 (batch) has 786.43K more context (4x larger).
| Feature | NewUnion Alpha (stealth) | Kimi K3 (batch) (MoonshotAI) |
|---|---|---|
| Input Price prompt tokens per 1M | $0 | $3 |
| Completion Price per 1M tokens | $0 | $15 |
| Sample Workload Cost 1M input + 500K output | $0 | $10.5 |
| Context Window | 262.14K | 1.05M |
| Release Date |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | Union Alpha | On the standard 1M input plus 500K output workload, Union Alpha is estimated at $0 vs $10.5 for Kimi K3 (batch), saving $10.5 (100% lower). |
| High-volume input processing | Union Alpha | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | Union Alpha | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | Kimi K3 (batch) | A larger context window leaves more room for retrieved passages, conversation history, or source files. |
Related Alternatives
- Kimi K2.7 Code (free) can replace Kimi K3 (batch) when lower sample workload cost matters most: $0.
- Kimi K2.6 (free) can replace Kimi K3 (batch) when lower sample workload cost matters most: $0.
- Kimi K2.5 can replace Kimi K3 (batch) when lower sample workload cost matters most: $1.57.
- Kimi K2 0711 can replace Kimi K3 (batch) when lower sample workload cost matters most: $1.72.
- Grok 4.20 Multi-Agent offers 2M context with $2.5 sample workload cost.
- Grok 4.20 offers 2M context with $2.5 sample workload cost.
- DeepSeek V4 Flash 0731 offers 1.31M context with $0.12 sample workload cost.
- GLM 5.3 Flash offers 1.31M context with $0.24 sample workload cost.
- Qwen3.8 Max (0902) · Qwen · #1
- GPT-5.6 Luna · OpenAI · #2
- Hy4 preview · Tencent · #3
- DeepSeek V4 Flash 0731 · DeepSeek · #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 hubsstealth catalog
Review all tracked stealth models before deciding whether this matchup is the right shortlist.
Open stealth modelsMoonshotAI catalog
Check other MoonshotAI models with comparable pricing, context, or release timing.
Open MoonshotAI modelsUnion Alpha is a multimodal model built for research, coding, and agentic workflows, while delivering frontier-level performance across a broad range of general-purpose tasks. Union Alpha is a stealth model....
Kimi K3 is a 2.8T parameter open-weight multimodal reasoning model from Moonshot AI. It is suited for complex coding, knowledge work, and long-horizon agentic workflows, and is particularly strong at...