How much does Gemini 3.1 Pro Preview Custom Tools cost per million tokens?

Gemini 3.1 Pro Preview Custom Tools costs $2 per million input tokens and $12 per million output tokens at list price, and $0.2 per million cached input tokens.

What is the context window of Gemini 3.1 Pro Preview Custom Tools?

Gemini 3.1 Pro Preview Custom Tools accepts up to 1,048,576 tokens of context and returns up to 65,536 output tokens.

How much do 1,000 chat messages cost with Gemini 3.1 Pro Preview Custom Tools?

About $8.00, assuming 1,000 input + 500 output tokens per message.

Is there a cheaper alternative to Gemini 3.1 Pro Preview Custom Tools?

In the same price range, OpenAI GPT-6.1 Sol Pro ($2 / $10), OpenAI GPT-6.1 Sol ($2 / $10), Anthropic Claude Sonnet 5.5 ($2 / $10) cost less per token. Quality differs: test on your own prompts.

Where can I buy Google API credits for less?

Discount credit books resell OpenRouter usage below face value within their depth, OpenRouter adds a 5.5% card fee, and Google sells its own credits at face value. The live table on this page ranks them for $100 of usage.

Google · live price

Gemini 3.1 Pro Preview Custom Tools API pricing

Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party...

Mid-range ($1–5 per 1M)Tool callingReasoningaudio inputimage inputvideo inputfile input

Input: $2; per 1M tokens
Output: $12; per 1M tokens
Cached input: $0.2; per 1M tokens
Context: 1.0M; 66K max output

List price from OpenRouter, which passes Google's price through without markup. Refreshed hourly. Released February 25, 2026. Model id google/gemini-3.1-pro-preview-customtools.

What Gemini 3.1 Pro Preview Custom Tools costs in practice

At list price, before any batch or caching discount.

1,000 chat messages

$8.00

1,000 input + 500 output tokens each

1,000 RAG questions

$22.00

8,000 input + 500 output tokens each

100 coding-agent steps

$8.40

30,000 input + 2,000 output tokens each, no caching

Gemini 3.1 Pro Preview Custom Tools price history

No price change since we started tracking on 2026-10-01. We record prices daily; changes will show here.

Gemini 3.1 Pro Preview Custom Tools price by host

One host serves this model through OpenRouter.

Google AI Studio$2 in · $12 out · 1.0M ctx · 100.0% uptime 24h

Where to buy Google credits for less

Gemini 3.1 Pro Preview Custom Tools costs the same per token everywhere it's sold through OpenRouter. What changes is the price of the credits. Live quotes for $100 of usage:

#	Where you buy	You payYou pay for $100.00 of usage	vs list price	Price source
1	OrbioCardCheapest right now Credits from a discount book, plus a 5% platform fee and card processing, both included in the quote.	$85.10 incl. $2.60 card processing	-14.9%	live quote
2	smaaartCard Credits from a discount book, plus a 5% platform fee on face value. Card processing and taxes shown at checkout.	$95.00 + card processing and tax at checkout (not in this number)	-5.0%	live quote
3	Direct from the labCard Prepaid credits at face value (OpenAI, Anthropic, Google…). Taxes may apply.	$100.00 no top-up fee	list price	face value
4	OpenRouterCrypto 5% on crypto purchases. No markup on model prices.	$105.00 fees included	+5.0%	published fee
5	OpenRouterCard 5.5% on card purchases, $0.80 minimum. No markup on model prices.	$105.50 fees included	+5.5%	published fee

Disclosure: this site is run by the team behind smaaart, one of the options compared. Tables are ranked by price only, from live quotes and published fees, including when smaaart isn't first. How we compare

Gemini 3.1 Pro Preview Custom Tools cost calculator

Enter your monthly tokens to price your own usage.

Model$2.00 in / $12.00 out per 1M tokens · list price, liveInput tokens / month (millions)Output tokens / month (millions)

Usage at list price$220.00/ month

Cheaper alternatives to Gemini 3.1 Pro Preview Custom Tools

Other labs' models in the same price range or the one below, cheaper per token.

Model	Input / 1M	Output / 1M	Blended 3:1	Context
OpenAI: GPT-6.1 Sol Pro	$2	$10	$4	1.1M
OpenAI: GPT-6.1 Sol	$2	$10	$4	1.1M
Anthropic: Claude Sonnet 5.5	$2	$10	$4	1M
Z.ai: GLM 5.3 Prime	$2.80	$8.80	$4.30	1M
OpenAI: GPT-6 Luna Pro	$0.1	$0.5	$0.2	1.1M
OpenAI: GPT-6 Luna	$0.1	$0.5	$0.2	1.1M

Other Google models

Model	Input / 1M	Output / 1M	Blended 3:1	Context
Nano Banana 2 (Gemini 3.1 Flash Image Preview)	$0.5	$3	$1.13	66K
Gemini 3.1 Flash Lite Preview	$0.25	$1.50	$0.563	1.0M
Gemini 3.1 Pro Preview	$2	$12	$4.50	1.0M
Gemma 4 31B	$0.09	$0.34	$0.152	262K
Gemma 4 26B A4B	$0.09	$0.3	$0.143	262K
Gemini 3 Flash Preview	$0.5	$3	$1.13	1.0M

All Google API prices