Which is cheaper, Claude Sonnet 4.5 or Gemini 2.5 Pro?

Gemini 2.5 Pro is the cheaper of the two: one 1,000-word request costs about 4,243 toman, about 1.6× cheaper than Claude Sonnet 4.5.

Which one has the larger context window?

Gemini 2.5 Pro, with 1,048,576 tokens.

Claude Sonnet 4.5 vs Gemini 2.5 Pro

Both sit behind the same key and the same code on uttapen — the only thing that changes is the model string, so you can run each of them against your own workload without touching anything else. On cost, Gemini 2.5 Pro comes out about 1.6× cheaper.

Feature	Claude Sonnet 4.5	Gemini 2.5 Pro
Provider	Anthropic	Google
Model id	anthropic/claude-sonnet-4.5	google/gemini-2.5-pro
Context	1,000,000 tokens	1,048,576 tokens
Max output	64,000 tokens	65,536 tokens
Input / 1M tokens	870,375 toman	362,656 toman
Output / 1M tokens	4,351,875 toman	2,901,250 toman
≈ one 1,000-word request	6,789 toman	4,243 toman
Input caching	87,038 toman / 1M	36,266 toman / 1M
Image input	Yes	Yes
File input	Yes	Yes
Tool calling	Yes	Yes
JSON output	Yes	Yes
Reasoning mode	Yes	Yes

Which one for what?

Claude Sonnet 4.5

Multi-step problems, maths, and tracking down a bug
Whole documents or a codebase in a single request
Reading screenshots, invoices, and scanned forms
Agents that call your own APIs and database

6,789 toman per 1,000 words · Model page

Gemini 2.5 Pro

Multi-step problems, maths, and tracking down a bug
Whole documents or a codebase in a single request
Reading screenshots, invoices, and scanned forms
Agents that call your own APIs and database

4,243 toman per 1,000 words · Model page

Run both with the same code

Swap the model value between the two ids and send the same request twice; what each answer cost comes back in the X-Uttapen-Cost-Toman header.

curl https://api.uttapen.ir/v1/chat/completions \
  -H "Authorization: Bearer sk-up-…" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-sonnet-4.5",
    "messages": [{"role": "user", "content": "Introduce yourself in one sentence."}],
    "stream": true
  }'

from openai import OpenAI

client = OpenAI(
    base_url="https://api.uttapen.ir/v1",
    api_key="sk-up-…",
)

stream = client.chat.completions.create(
    model="anthropic/claude-sonnet-4.5",
    messages=[{"role": "user", "content": "Introduce yourself in one sentence."}],
    stream=True,
)
for chunk in stream:
    print(chunk.choices[0].delta.content or "", end="", flush=True)

import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.uttapen.ir/v1",
  apiKey: "sk-up-…",
});

const stream = await client.chat.completions.create({
  model: "anthropic/claude-sonnet-4.5",
  messages: [{ role: "user", content: "Introduce yourself in one sentence." }],
  stream: true,
});
for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta?.content ?? "");
}

<?php
// composer require openai-php/client guzzlehttp/guzzle
$client = OpenAI::factory()
    ->withBaseUri('https://api.uttapen.ir/v1')
    ->withApiKey('sk-up-…')
    ->make();

$result = $client->chat()->create([
    'model' => 'anthropic/claude-sonnet-4.5',
    'messages' => [['role' => 'user', 'content' => 'Introduce yourself in one sentence.']],
]);
echo $result->choices[0]->message->content;

package main

import (
	"context"
	"fmt"

	"github.com/openai/openai-go"
	"github.com/openai/openai-go/option"
)

func main() {
	client := openai.NewClient(
		option.WithBaseURL("https://api.uttapen.ir/v1"),
		option.WithAPIKey("sk-up-…"),
	)
	resp, err := client.Chat.Completions.New(context.Background(), openai.ChatCompletionNewParams{
		Model:    "anthropic/claude-sonnet-4.5",
		Messages: []openai.ChatCompletionMessageParamUnion{openai.UserMessage("Introduce yourself in one sentence.")},
	})
	if err != nil {
		panic(err)
	}
	fmt.Println(resp.Choices[0].Message.Content)
}

model = "google/gemini-2.5-pro"

More comparisons: all pairs · model rankings · full catalogue

base_url = https://api.uttapen.ir/v1