# Gemini 3.1 Pro Preview Customtools API Pricing

As of October 10, 2026, Gemini 3.1 Pro Preview Customtools costs $2.00 per 1M input tokens and $12.00 per 1M output tokens on Google AI Studio, with cache reads at $0.20 per 1M tokens. It has a 1,048,576-token context window and returns up to 65,536 tokens per response.

- Page: https://models.litellm.ai/models/gemini-3.1-pro-preview-customtools
- Lab: Google
- LiteLLM model name: `gemini/gemini-3.1-pro-preview-customtools`
- Context window: 1,048,576 tokens
- Max output: 65,536 tokens
- Added to LiteLLM: February 2026
- Prices updated: October 10, 2026

## Pricing by provider

Token prices in USD per 1M tokens.

| Provider | Model name | Input | Output | Cache read | Per image | Per second | Context |
|---|---|---|---|---|---|---|---|
| Google AI Studio | `gemini/gemini-3.1-pro-preview-customtools` | $2.00 | $12.00 | $0.20 | – | – | 1M |
| AIHubMix | `aihubmix/gemini-3.1-pro-preview-customtools` | $2.00 | $12.00 | $0.20 | – | – | 1M |
| Google Vertex AI | `vertex_ai/gemini-3.1-pro-preview-customtools` | $2.00 | $12.00 | $0.20 | $0.00012 | – | 1M |

## Cost examples

1,000 requests with 2,000 input and 500 output tokens each:

- Google AI Studio: $10.00
- AIHubMix: $10.00
- Google Vertex AI: $10.00
- Google AI Studio batch: $5.00

100 long-document requests with 100,000 input and 2,000 output tokens each:

- Google AI Studio: $22.40
- AIHubMix: $22.40
- Google Vertex AI: $22.40

## Features

Supported: Function calling, Structured output, Image input, PDF input, Audio input, Video input, Reasoning, Prompt caching, Web search.

## Use it with LiteLLM

```python
from litellm import completion

response = completion(
    model="gemini/gemini-3.1-pro-preview-customtools",
    messages=[{"role": "user", "content": "Hello!"}],
)
```

## FAQ

### How much does Gemini 3.1 Pro Preview Customtools cost?

Gemini 3.1 Pro Preview Customtools costs $2.00 per 1M input tokens and $12.00 per 1M output tokens on Google AI Studio, with cache reads at $0.20 per 1M tokens. Batch requests cost $1.00 per 1M input tokens and $6.00 per 1M output tokens. Above 200K input tokens, input costs $4.00 and output costs $18.00 per 1M tokens.

### What is the context window of Gemini 3.1 Pro Preview Customtools?

Gemini 3.1 Pro Preview Customtools has a 1,048,576-token context window and returns up to 65,536 tokens per response.

### Which providers offer Gemini 3.1 Pro Preview Customtools?

Gemini 3.1 Pro Preview Customtools is available from 3 providers through LiteLLM: Google AI Studio, AIHubMix and Google Vertex AI.

### How do I call Gemini 3.1 Pro Preview Customtools with an OpenAI-compatible API?

Use the LiteLLM Python SDK with model="gemini/gemini-3.1-pro-preview-customtools", or add the model to the LiteLLM proxy's config.yaml and send requests to /v1/chat/completions from any OpenAI client. LiteLLM tracks the cost of every request at the prices on this page.

### What features does Gemini 3.1 Pro Preview Customtools support?

Gemini 3.1 Pro Preview Customtools supports function calling, structured output, image input, PDF input, audio input, video input, reasoning, prompt caching and web search.

### When did LiteLLM add Gemini 3.1 Pro Preview Customtools?

Gemini 3.1 Pro Preview Customtools was added to LiteLLM's model price file in February 2026.

Source: LiteLLM model price file, https://github.com/BerriAI/litellm/blob/main/model_prices_and_context_window.json