GPT-5.6 Luna Pro is $0.3 cheaper per 1M input tokens (60% lower; 2.5x difference).
API cost decision in 10 seconds
NewSeed 2.1 Turbo vs GPT-5.6 Luna Pro
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 $1.75 for Seed 2.1 Turbo, saving $0.95 (54.3% lower).
Cost-first pickGPT-5.6 Luna Pro
Context-first pickGPT-5.6 Luna Pro
Sample savings$0.9554.3%
10x traffic gap$9.5
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 $9.5. 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 | Seed 2.1 Turbo | GPT-5.6 Luna Pro |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | GPT-5.6 Luna Pro | $3.75 | $1.6 |
| Balanced workload | 1M input + 1M output | GPT-5.6 Luna Pro | $3 | $1.4 |
| Output-heavy chatbot | 1M input + 5M output | GPT-5.6 Luna Pro | $13 | $6.2 |
GPT-5.6 Luna Pro is $1.3 cheaper per 1M output tokens (52% lower; 2.08x difference).
GPT-5.6 Luna Pro has 787.86K more context (4.01x larger).
GPT-5.6 Luna Pro is $0.95 cheaper on the standard workload (54.3% 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 $1.75 for Seed 2.1 Turbo and $0.8 for GPT-5.6 Luna Pro.
Choose Seed 2.1 Turbo when its provider, model quality, latency, or availability is more important than the numeric price/context winner.
Choose GPT-5.6 Luna Pro when you care most about lower input-token price, lower output-token price, and larger context window.
- On the standard 1M input plus 500K output workload, GPT-5.6 Luna Pro is estimated at $0.8 vs $1.75 for Seed 2.1 Turbo, saving $0.95 (54.3% lower).
- GPT-5.6 Luna Pro is $0.95 cheaper on the standard workload (54.3% lower).
- GPT-5.6 Luna Pro is $0.3 cheaper per 1M input tokens (60% lower; 2.5x difference).
- GPT-5.6 Luna Pro is $1.3 cheaper per 1M output tokens (52% lower; 2.08x difference).
- GPT-5.6 Luna Pro has 787.86K more context (4.01x larger).
| Feature | NewSeed 2.1 Turbo (ByteDance Seed) | GPT-5.6 Luna Pro (OpenAI) |
|---|---|---|
| Input Price prompt tokens per 1M | $0.5 | $0.2 |
| Completion Price per 1M tokens | $2.5 | $1.2 |
| Sample Workload Cost 1M input + 500K output | $1.75 | $0.8 |
| Context Window | 262.14K | 1.05M |
| 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 $1.75 for Seed 2.1 Turbo, saving $0.95 (54.3% 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
- Seed 1.6 Flash can replace Seed 2.1 Turbo when lower sample workload cost matters most: $0.22.
- Seed-2.0-Mini can replace Seed 2.1 Turbo when lower sample workload cost matters most: $0.3.
- Seed-2.0-Lite can replace Seed 2.1 Turbo when lower sample workload cost matters most: $1.25.
- Seed 1.6 can replace Seed 2.1 Turbo when lower sample workload cost matters most: $1.25.
- 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.
- Llama 4 Scout offers 1.31M context with $0.25 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 OpenAI modelsSeed 2.1 Turbo is a multimodal model from ByteDance Seed for coding and long-horizon agent workflows. It is suited for end-to-end software delivery, multi-step task execution, and understanding visual and...
GPT-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