Claude Sonnet 5.5 vs Gemini 4 Argon

As of October 21, 2026, Claude Sonnet 5.5 and Gemini 4 Argon cost the same: $2.00 per 1M input tokens and $10.00 per 1M output tokens. Gemini 4 Argon has the larger context window: 1,048,576 tokens versus 1,000,000. Gemini 4 Argon's price is introductory through November 30, 2026.

Prices from LiteLLM's price fileChecked October 21, 2026

Claude Sonnet 5.5 vs Gemini 4 Argon side by side

Headline prices in US dollars per 1M tokens: each model's own lab where it sells it, otherwise its cheapest provider. Source: LiteLLM model price file, as of October 21, 2026.
	Claude Sonnet 5.5	Gemini 4 Argon
Input, per 1M tokens	$2.00	$2.00
Output, per 1M tokens	$10.00	$10.00
Cache read, per 1M tokens	$0.10	$0.10
Cache write, per 1M tokens	$2.50	–
Context window	1,000,000 tokens	1,048,576 tokens
Max output	128,000 tokens	1,048,576 tokens
Image input	Yes	Yes
Tool calling	Yes	Yes
Structured output (JSON)	Yes	Yes
Prompt caching	Yes	Yes
Reasoning	Yes	Yes
Providers on LiteLLM	7	3
Price shown is from	Anthropic	Google AI Studio, introductory until November 30, 2026
Added to LiteLLM	September 28, 2026	October 13, 2026

Cheapest provider for each

Claude Sonnet 5.5: Anthropic at $2.00 input and $10.00 output per 1M tokens (claude-sonnet-5-5)
Gemini 4 Argon: Google AI Studio at $2.00 input and $10.00 output per 1M tokens (gemini/gemini-4-argon)

Benchmark scores

From the Epoch AI Benchmarking Hub (CC BY 4.0), data as of October 13, 2026. Some results were run by Epoch and others collected by Epoch from each benchmark's own leaderboard, linked in the first column. Each model's best reported reasoning setting is shown in brackets. Higher is better. Only benchmarks with a score for both models are shown.
Benchmark	Claude Sonnet 5.5	Gemini 4 Argon
Overall
Epoch Capabilities Index	166.2	166.4
Coding and agents
FrontierCode	52.1% (xhigh)	47.5% (medium)
FrontierSWE	61.9% (max)	55.0% (high)
APEX-Agents	75.5% (max)	82.4%
Reasoning and knowledge
GPQA Diamond	95.6% (max)	96.4% (high)
SimpleQA Verified	46.5% (max)	76.0% (high)
Math
FrontierMath (tiers 1-3)	88.8% (max)	86.0% (high)
FrontierMath (tier 4)	80.5% (max)	78.0% (high)
OTIS Mock AIME 2024-2025	100.0% (max)	100.0% (high)

When to pick which

Pick Claude Sonnet 5.5 for

Available from 7 providers through LiteLLM, vs 3.

Pick Gemini 4 Argon for

Returns up to 1,048,576 tokens per response, vs 128,000.

From differences in the data above only; where the data is equal, no reason is given.

Call Claude Sonnet 5.5 or Gemini 4 Argon with LiteLLM

Both use the OpenAI format through LiteLLM, so switching is a model name change. Set each provider's API key in the environment first.

Python SDK

from litellm import completion

messages = [{"role": "user", "content": "Hello!"}]

# Claude Sonnet 5.5
response = completion(model="claude-sonnet-5-5", messages=messages)

# Gemini 4 Argon
response = completion(model="gemini/gemini-4-argon", messages=messages)

# Claude Sonnet 5.5, falling back to Gemini 4 Argon if the call fails
response = completion(model="claude-sonnet-5-5", messages=messages, fallbacks=["gemini/gemini-4-argon"])

FAQ

Which is cheaper, Claude Sonnet 5.5 or Gemini 4 Argon?

They cost the same: $2.00 per 1M input tokens and $10.00 per 1M output tokens, as of October 21, 2026.

Which has the larger context window, Claude Sonnet 5.5 or Gemini 4 Argon?

Gemini 4 Argon has the larger context window: 1,048,576 tokens, versus 1,000,000 for Claude Sonnet 5.5.

Can I switch from Claude Sonnet 5.5 to Gemini 4 Argon without changing my code?

Yes. Through LiteLLM both use the OpenAI format, so switching means changing the model name from "claude-sonnet-5-5" to "gemini/gemini-4-argon", or pointing a LiteLLM gateway model alias at the other model. You can also use one as a fallback for the other.