Cheap Gemini 3.1 Pro API

What a top-up buys on Gemini 3.1 Pro

Output-token count only; input tokens are cheaper. First top-up is at least 2.5×.

When to pick Gemini 3.1 Pro

Gemini 3.1 Pro costs $0.0090 per 1,500-in/500-out request at list price, $0.0045 effective. It sits in the mid price range — a good default for production apps.

Gemini 3.1 Pro vs similarly priced models

Nearest models to Gemini 3.1 Pro by blended price (3 input : 1 output). All run on one Somnus key.

Getting the most out of Gemini 3.1 Pro for less

• Input is 6.0× cheaper than output on Gemini 3.1 Pro, so long context with short answers is the cheapest pattern.
• A $200 top-up gives $500 credit — about 111M blended Gemini 3.1 Pro tokens.
• Mix models: send easy steps to DeepSeek V4 Flash and keep Gemini 3.1 Pro for the steps that need it.

Other Gemini models on Somnus

Every Google model shares the same key and balance.

Use Gemini 3.1 Pro

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.SOMNUS_API_KEY,
  baseURL: "https://gateway-production-c837.up.railway.app/v1",
});

const resp = await client.chat.completions.create({
  model: "claude-sonnet-5",
  messages: [
    {"role": "user", "content": "Summarise this in one line"}
  ],
});
console.log(resp.choices[0].message.content);

Copy the exact model id from your dashboard.

Questions

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