GLM 4.5 Air (free) is free for input tokens while Gemini 3.1 Pro Preview costs $2 per 1M tokens.
API cost decision in 10 seconds
Gemini 3.1 Pro Preview vs GLM 4.5 Air (free)
Pick GLM 4.5 Air (free) for lower cost; pick Gemini 3.1 Pro Preview 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 GLM 4.5 Air (free) for lower cost; pick Gemini 3.1 Pro Preview only if the larger context window matters more.
On the standard 1M input plus 500K output workload, GLM 4.5 Air (free) is estimated at $0 vs $8 for Gemini 3.1 Pro Preview, saving $8 (100% lower).
Cost-first pickGLM 4.5 Air (free)
Context-first pickGemini 3.1 Pro Preview
Sample savings$8100%
10x traffic gap$80
Gemini 3.1 Pro Preview has more context, but GLM 4.5 Air (free) saves $8 on the standard workload. At 10x that traffic, the same price gap is about $80. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
GLM 4.5 Air (free) stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | Gemini 3.1 Pro Preview | GLM 4.5 Air (free) |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | GLM 4.5 Air (free) | $16 | $0 |
| Balanced workload | 1M input + 1M output | GLM 4.5 Air (free) | $14 | $0 |
| Output-heavy chatbot | 1M input + 5M output | GLM 4.5 Air (free) | $62 | $0 |
GLM 4.5 Air (free) is free for output tokens while Gemini 3.1 Pro Preview costs $12 per 1M tokens.
Gemini 3.1 Pro Preview has 917.5K more context (8x larger).
GLM 4.5 Air (free) is free for the standard workload while the other model is estimated at $8.
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
GLM 4.5 Air (free) has the lower input price; GLM 4.5 Air (free) has the lower output price; Gemini 3.1 Pro Preview offers the larger context window. For the 1M input plus 500K output sample, GLM 4.5 Air (free) is cheaper for the standard workload.
For a 1M input token plus 500K output token workload, the estimated API cost is $8 for Gemini 3.1 Pro Preview and $0 for GLM 4.5 Air (free).
Choose Gemini 3.1 Pro Preview when you care most about larger context window.
Choose GLM 4.5 Air (free) when you care most about lower input-token price, and lower output-token price.
- On the standard 1M input plus 500K output workload, GLM 4.5 Air (free) is estimated at $0 vs $8 for Gemini 3.1 Pro Preview, saving $8 (100% lower).
- GLM 4.5 Air (free) is free for the standard workload while the other model is estimated at $8.
- GLM 4.5 Air (free) is free for input tokens while Gemini 3.1 Pro Preview costs $2 per 1M tokens.
- GLM 4.5 Air (free) is free for output tokens while Gemini 3.1 Pro Preview costs $12 per 1M tokens.
- Gemini 3.1 Pro Preview has 917.5K more context (8x larger).
| Feature | Gemini 3.1 Pro Preview (Google) | GLM 4.5 Air (free) (Z.ai) |
|---|---|---|
| Input Price prompt tokens per 1M | $2 | $0 |
| Completion Price per 1M tokens | $12 | $0 |
| Sample Workload Cost 1M input + 500K output | $8 | $0 |
| Context Window | 1.05M | 131.07K |
| Release Date | ||
| Popularity | #28 | #41 |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | GLM 4.5 Air (free) | On the standard 1M input plus 500K output workload, GLM 4.5 Air (free) is estimated at $0 vs $8 for Gemini 3.1 Pro Preview, saving $8 (100% lower). |
| High-volume input processing | GLM 4.5 Air (free) | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | GLM 4.5 Air (free) | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | Gemini 3.1 Pro Preview | A larger context window leaves more room for retrieved passages, conversation history, or source files. |
Related Alternatives
- Gemma 4 31B (free) can replace Gemini 3.1 Pro Preview when lower sample workload cost matters most: $0.
- Gemma 4 26B A4B (free) can replace Gemini 3.1 Pro Preview when lower sample workload cost matters most: $0.
- Lyria 3 Clip Preview can replace Gemini 3.1 Pro Preview when lower sample workload cost matters most: $0.
- Lyria 3 Pro Preview can replace Gemini 3.1 Pro Preview 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.
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