# Gemini 3.1 Pro Preview API pricing

Gemini 3.1 Pro Preview is an earlier Google model, still sold. It costs $2 per million tokens it reads and $12 per million it writes, $4.50 on a mix of 3 read for each 1 written. Google's newest models are Gemini 4 Argon, Gemini 3.8 Flash and Gemini 3.5 Flash-Lite. Below are every price Google lists for it, and what 8 everyday jobs cost a month on it.

- Page: https://tecyfy.com/prices/gemini-3-1-pro-preview
- Maker: Google

## Price per million tokens, in US dollars

| | Price |
| --- | --: |
| Input | $2 |
| Cached input | $0.20 |
| Cache write | not listed |
| Output | $12 |
| Blend, 3 read for each 1 written | $4.50 |
| Batch input | not listed |
| Batch output | not listed |
| Long prompt input (over 200K tokens) | $4 |
| Long prompt output | $18 |
| Context window, tokens | 1.05M |
| Longest answer, tokens | 66K |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | not scored |

## What 8 everyday jobs cost a month

Each job at its usual runs a day, for 30 days, at the standard price.

| Job | Tokens in, out, runs a day | A run | A month |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | 0.66 cents | $19.80 |
| A hard question, with thinking | 300, 1,400, 100 | 1.7 cents | $52.20 |
| A long report, summarised | 60,000, 2,000, 20 | 14 cents | $86.40 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $1.54 | $463 |
| A support bot's reply | 4,000, 300, 2,000 | 0.8 cents | $480 |
| Sort a message into a category | 250, 5, 50,000 | 0.056 cents | $840 |
| Read an invoice into fields | 1,500, 250, 1,000 | 0.6 cents | $180 |
| Review a pull request | 25,000, 4,500, 50 | 10 cents | $156 |

## Questions

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

Gemini 3.1 Pro Preview costs $2 per million input tokens, the text it reads, and $12 per million output tokens, the text it writes, thinking included. On a mix of 3 tokens read for each 1 written, that is $4.50 per million.

### How much does cached input cost on Gemini 3.1 Pro Preview?

Text Gemini 3.1 Pro Preview reads again from the cache costs $0.20 per million tokens, against $2 the first time. Google lists no separate price for writing to the cache.

### Does Gemini 3.1 Pro Preview have a batch price?

Not on Google's price page, which lists no batch price for Gemini 3.1 Pro Preview. The cache still lowers the price of text it reads again.

### Does a long prompt cost more on Gemini 3.1 Pro Preview?

Yes. Once a prompt passes 200K tokens, the whole request costs $4 per million tokens read and $18 per million written, against $2 and $12 below that.

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

Gemini 3.1 Pro Preview holds 1.05M tokens at once, about 1,600 pages of English text, and writes up to 66K tokens in one answer. The window holds your instructions, the files you attach, the conversation so far and the answer.

### How good is Gemini 3.1 Pro Preview?

Epoch AI has no independent score for Gemini 3.1 Pro Preview yet. Run the same 10 tasks of your own on it and on a model you know, and compare the answers and the bills.

### Should I still use Gemini 3.1 Pro Preview?

It is still sold, so it keeps working, but Google's newest models are Gemini 4 Argon, Gemini 3.8 Flash and Gemini 3.5 Flash-Lite. Compare its price with theirs below, and run your own tasks on the newer model before you move.

### What does a support bot cost a month on Gemini 3.1 Pro Preview?

At 2,000 replies a day, each reading 4,000 tokens (50 percent of them from cache) and writing 300, a support bot costs 0.8 cents a reply on Gemini 3.1 Pro Preview, $480 a month.

### What does an AI agent task cost on Gemini 3.1 Pro Preview?

One 40-turn task that reads 2,800,000 tokens in all, 90 percent of them from cache, and writes 40,000, costs $1.54 on Gemini 3.1 Pro Preview. At 10 tasks a day that is $463 a month.

## Sources

- [Google: API prices](https://ai.google.dev/gemini-api/docs/pricing)
- Every model's prices as [JSON](https://tecyfy.com/prices.json) or [CSV](https://tecyfy.com/prices.csv), free to use

## Compare

- [Gemini 3.1 Pro Preview vs Gemini 4 Argon](https://tecyfy.com/prices/compare/gemini-3-1-pro-preview-vs-gemini-4-argon.md)
- [Gemini 3.1 Pro Preview vs Gemini 3.8 Flash](https://tecyfy.com/prices/compare/gemini-3-1-pro-preview-vs-gemini-3-8-flash.md)
- [Gemini 3.1 Pro Preview vs Gemini 3.5 Flash-Lite](https://tecyfy.com/prices/compare/gemini-3-1-pro-preview-vs-gemini-3-5-flash-lite.md)

## Google's other models

- [Gemini 4 Argon](https://tecyfy.com/prices/gemini-4-argon.md)
- [Gemini 3.8 Flash](https://tecyfy.com/prices/gemini-3-8-flash.md)
- [Gemini 3.5 Flash-Lite](https://tecyfy.com/prices/gemini-3-5-flash-lite.md)
- [Gemini 3.6 Flash](https://tecyfy.com/prices/gemini-3-6-flash.md)
- [Gemini 3.1 Flash-Lite](https://tecyfy.com/prices/gemini-3-1-flash-lite.md)
- [Gemini 3 Flash Preview](https://tecyfy.com/prices/gemini-3-flash-preview.md)
- [Gemini 2.5 Pro](https://tecyfy.com/prices/gemini-2-5-pro.md)
- [Gemini 2.5 Flash](https://tecyfy.com/prices/gemini-2-5-flash.md)
- [Gemini 2.5 Flash-Lite](https://tecyfy.com/prices/gemini-2-5-flash-lite.md)