Mercury 2.5 Preview is $0.16 cheaper per 1M input tokens (80% lower; 5x difference).
API cost decision in 10 seconds
🔥GPT-5.6 Luna vs NewMercury 2.5 Preview
Pick Mercury 2.5 Preview for lower cost; pick GPT-5.6 Luna only if the larger context window matters more.
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Data confirmed:
Prices normalized to USD per 1M tokens
Sample workload: 1M input + 500K output
Budget verdict
Pick Mercury 2.5 Preview for lower cost; pick GPT-5.6 Luna only if the larger context window matters more.
On the standard 1M input plus 500K output workload, Mercury 2.5 Preview is estimated at $0.11 vs $0.8 for GPT-5.6 Luna, saving $0.69 (85.6% lower).
Cost-first pickMercury 2.5 Preview
Context-first pickGPT-5.6 Luna
Sample savings$0.6985.6%
10x traffic gap$6.85
GPT-5.6 Luna has more context, but Mercury 2.5 Preview saves $0.69 on the standard workload. At 10x that traffic, the same price gap is about $6.85. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
Mercury 2.5 Preview stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | GPT-5.6 Luna | Mercury 2.5 Preview |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | Mercury 2.5 Preview | $1.6 | $0.28 |
| Balanced workload | 1M input + 1M output | Mercury 2.5 Preview | $1.4 | $0.19 |
| Output-heavy chatbot | 1M input + 5M output | Mercury 2.5 Preview | $6.2 | $0.79 |
Mercury 2.5 Preview is $1.05 cheaper per 1M output tokens (87.5% lower; 8x difference).
GPT-5.6 Luna has 790K more context (4.04x larger).
Mercury 2.5 Preview is $0.69 cheaper on the standard workload (85.6% 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
Mercury 2.5 Preview has the lower input price; Mercury 2.5 Preview has the lower output price; GPT-5.6 Luna offers the larger context window. For the 1M input plus 500K output sample, Mercury 2.5 Preview 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 and $0.11 for Mercury 2.5 Preview.
Choose GPT-5.6 Luna when you care most about larger context window.
Choose Mercury 2.5 Preview when you care most about lower input-token price, and lower output-token price.
- On the standard 1M input plus 500K output workload, Mercury 2.5 Preview is estimated at $0.11 vs $0.8 for GPT-5.6 Luna, saving $0.69 (85.6% lower).
- Mercury 2.5 Preview is $0.69 cheaper on the standard workload (85.6% lower).
- Mercury 2.5 Preview is $0.16 cheaper per 1M input tokens (80% lower; 5x difference).
- Mercury 2.5 Preview is $1.05 cheaper per 1M output tokens (87.5% lower; 8x difference).
- GPT-5.6 Luna has 790K more context (4.04x larger).
| Feature | 🔥GPT-5.6 Luna (OpenAI) | NewMercury 2.5 Preview (Inception) |
|---|---|---|
| Input Price prompt tokens per 1M | $0.2 | $0.04 |
| Completion Price per 1M tokens | $1.2 | $0.15 |
| Sample Workload Cost 1M input + 500K output | $0.8 | $0.11 |
| Context Window | 1.05M | 260K |
| Release Date | ||
| Popularity | #2 |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | Mercury 2.5 Preview | On the standard 1M input plus 500K output workload, Mercury 2.5 Preview is estimated at $0.11 vs $0.8 for GPT-5.6 Luna, saving $0.69 (85.6% lower). |
| High-volume input processing | Mercury 2.5 Preview | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | Mercury 2.5 Preview | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | GPT-5.6 Luna | 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 when lower sample workload cost matters most: $0.
- gpt-oss-20b (free) can replace GPT-5.6 Luna when lower sample workload cost matters most: $0.
- gpt-oss-20b can replace GPT-5.6 Luna when lower sample workload cost matters most: $0.1.
- gpt-oss-120b can replace GPT-5.6 Luna when lower sample workload cost matters most: $0.12.
- DeepSeek V4 Flash 0731 offers 1.31M context with $0.15 sample workload cost.
- GLM 5.3 Flash offers 1.31M context with $0.2 sample workload cost.
- DeepSeek V4 Flash Latest offers 1.31M context with $0.1 sample workload cost.
- Llama 4 Scout offers 1.31M context with $0.25 sample workload cost.
- DeepSeek V4 Flash 0731 · DeepSeek · #1
- GLM 5.3 Flash · Z.ai · #3
- MiMo-V2.5 · Xiaomi · #4
- Hy3 · Tencent · #5
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