GPT-5.6 Luna Pro is $0.8 cheaper per 1M input tokens (80% lower; 5x difference).
API cost decision in 10 seconds
GPT-5.6 Luna Pro vs Grok Build 0.1
Pick GPT-5.6 Luna Pro when budget and context both matter.
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Data confirmed:
Prices normalized to USD per 1M tokens
Sample workload: 1M input + 500K output
Budget verdict
Pick GPT-5.6 Luna Pro when budget and context both matter.
On the standard 1M input plus 500K output workload, GPT-5.6 Luna Pro is estimated at $0.8 vs $2 for Grok Build 0.1, saving $1.2 (60% lower).
Cost-first pickGPT-5.6 Luna Pro
Context-first pickGPT-5.6 Luna Pro
Sample savings$1.260%
10x traffic gap$12
GPT-5.6 Luna Pro is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $12. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
GPT-5.6 Luna Pro stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | GPT-5.6 Luna Pro | Grok Build 0.1 |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | GPT-5.6 Luna Pro | $1.6 | $6 |
| Balanced workload | 1M input + 1M output | GPT-5.6 Luna Pro | $1.4 | $3 |
| Output-heavy chatbot | 1M input + 5M output | GPT-5.6 Luna Pro | $6.2 | $11 |
GPT-5.6 Luna Pro is $0.8 cheaper per 1M output tokens (40% lower; 1.67x difference).
GPT-5.6 Luna Pro has 794K more context (4.1x larger).
GPT-5.6 Luna Pro is $1.2 cheaper on the standard workload (60% 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
GPT-5.6 Luna Pro has the lower input price; GPT-5.6 Luna Pro has the lower output price; GPT-5.6 Luna Pro offers the larger context window. For the 1M input plus 500K output sample, GPT-5.6 Luna Pro is cheaper for the standard workload.
For a 1M input token plus 500K output token workload, the estimated API cost is $0.8 for GPT-5.6 Luna Pro and $2 for Grok Build 0.1.
Choose GPT-5.6 Luna Pro when you care most about lower input-token price, lower output-token price, and larger context window.
Choose Grok Build 0.1 when its provider, model quality, latency, or availability is more important than the numeric price/context winner.
- On the standard 1M input plus 500K output workload, GPT-5.6 Luna Pro is estimated at $0.8 vs $2 for Grok Build 0.1, saving $1.2 (60% lower).
- GPT-5.6 Luna Pro is $1.2 cheaper on the standard workload (60% lower).
- GPT-5.6 Luna Pro is $0.8 cheaper per 1M input tokens (80% lower; 5x difference).
- GPT-5.6 Luna Pro is $0.8 cheaper per 1M output tokens (40% lower; 1.67x difference).
- GPT-5.6 Luna Pro has 794K more context (4.1x larger).
| Feature | GPT-5.6 Luna Pro (OpenAI) | Grok Build 0.1 (SpaceXAI) |
|---|---|---|
| Input Price prompt tokens per 1M | $0.2 | $1 |
| Completion Price per 1M tokens | $1.2 | $2 |
| Sample Workload Cost 1M input + 500K output | $0.8 | $2 |
| Context Window | 1.05M | 256K |
| Release Date |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | GPT-5.6 Luna Pro | On the standard 1M input plus 500K output workload, GPT-5.6 Luna Pro is estimated at $0.8 vs $2 for Grok Build 0.1, saving $1.2 (60% lower). |
| High-volume input processing | GPT-5.6 Luna Pro | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | GPT-5.6 Luna Pro | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | GPT-5.6 Luna Pro | A larger context window leaves more room for retrieved passages, conversation history, or source files. |
Related Alternatives
- gpt-oss-120b (free) can replace GPT-5.6 Luna Pro when lower sample workload cost matters most: $0.
- gpt-oss-20b (free) can replace GPT-5.6 Luna Pro when lower sample workload cost matters most: $0.
- gpt-oss-20b can replace GPT-5.6 Luna Pro when lower sample workload cost matters most: $0.1.
- gpt-oss-120b can replace GPT-5.6 Luna Pro when lower sample workload cost matters most: $0.12.
- 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 $0.17 sample workload cost.
- DeepSeek V4 Flash Latest offers 1.31M context with $0.11 sample workload cost.
- DeepSeek V4 Flash 0731 · DeepSeek · #1
- MiMo-V2.5 · Xiaomi · #2
- Hy3 · Tencent · #3
- Ox Alpha · stealth · #4
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Open SpaceXAI modelsGPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode
Grok Build 0.1 is SpaceXAI’s fast coding model trained specifically for agentic software engineering workflows. It supports text and image inputs with text output, and is optimized for interactive coding...