The AI arena is free today

Open Superagent

Claude Sonnet 4.5 vs Gemini 1.5 Flash

Claude Sonnet 4.5 leads the LLM Stats Score 32.1 to 6.0. Gemini 1.5 Flash is 22.9x cheaper per token.

Anthropic · Google · Updated for 2026

Which is better?

Claude Sonnet 4.5 leads the overall LLM Stats Score 32.1 to 6.0, ranking #110 overall.

In the 1 individual benchmarks reported for both models, Claude Sonnet 4.5 wins 1; this is a narrower head-to-head signal than the composite indexes.

On price, Gemini 1.5 Flash is roughly 22.9x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Gemini 1.5 Flash also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Sonnet 4.5

  • overall performance matters — it scores 32.1 and ranks #110 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 1 of 1 exact shared results
  • you want the most recent training data — it shipped Sep 2025

Choose Gemini 1.5 Flash

  • cost matters — it's about 22.9x cheaper per token
  • you process long inputs — it offers a 1,048,576 token context window

At a glance

The differences that matter most.

Claude Sonnet 4.5
Anthropic
Gemini 1.5 Flash
Google
Core performance indexes
LLM Stats Score
32.1
#110
6.0
#296
Reasoning
31.3
#111
5.6
#295
Coding
21.5
#90
-0.3
#246
Cost, coverage & limits
Benchmark wins
1 of 1
0 of 1
Input price
$3.00 / M
$0.15 / M
Output price
$15.00 / M
$0.60 / M
Context window
200,000
1,048,576

Capability indexes

Additional strengths measured across groups of related public benchmarks

3 shared
Index
Claude Sonnet 4.5
Gemini 1.5 Flash
Math
25.0#115
10.6#251
Vision
10.7#119
5.5#153
Multimodal
12.6#107
9.0#122
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

9 reported for Claude Sonnet 4.5 · 22 for Gemini 1.5 Flash

1 shared

Claude Sonnet 4.5 outperforms in 1 benchmarks (GPQA), while Gemini 1.5 Flash is better at 0 benchmarks.

Claude Sonnet 4.5 significantly outperforms across most benchmarks.

Tue Sep 22 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

Gemini 1.5 Flash costs less

For input processing, Claude Sonnet 4.5 ($3.00/1M tokens) is 20.0x more expensive than Gemini 1.5 Flash ($0.15/1M tokens).

For output processing, Claude Sonnet 4.5 ($15.00/1M tokens) is 25.0x more expensive than Gemini 1.5 Flash ($0.60/1M tokens).

In conclusion, Claude Sonnet 4.5 is more expensive than Gemini 1.5 Flash.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Tue Sep 22 2026 • llm-stats.com
Anthropic
Claude Sonnet 4.5
Input tokens$3.00
Output tokens$15.00
Best providerAnthropic
Google
Gemini 1.5 Flash
Input tokens$0.15
Output tokens$0.60
Best providerGoogle
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Gemini 1.5 Flash accepts 1,048,576 input tokens compared to Claude Sonnet 4.5's 200,000 tokens. Claude Sonnet 4.5 can generate longer responses up to 64,000 tokens, while Gemini 1.5 Flash is limited to 8,192 tokens.

Anthropic
Claude Sonnet 4.5
Input200,000 tokens
Output64,000 tokens
Google
Gemini 1.5 Flash
Input1,048,576 tokens
Output8,192 tokens
Tue Sep 22 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Sonnet 4.5 and Gemini 1.5 Flash support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Sonnet 4.5

Text
Images
Audio
Video

Gemini 1.5 Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Sonnet 4.5

Proprietary

Closed source

Gemini 1.5 Flash

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 4.5 was released on 2025-09-29, while Gemini 1.5 Flash was released on 2024-05-01.

Claude Sonnet 4.5 is 17 months newer than Gemini 1.5 Flash.

Claude Sonnet 4.5

Sep 29, 2025

11 months ago

1.4yr newer
Gemini 1.5 Flash

May 1, 2024

2.4 years ago

Knowledge Cutoff

When training data ends

Claude Sonnet 4.5 has a knowledge cutoff of 2025-01-31, while Gemini 1.5 Flash has a cutoff of 2023-11-01.

Claude Sonnet 4.5 has more recent training data (up to 2025-01-31), making it potentially better informed about events through that date compared to Gemini 1.5 Flash (2023-11-01).

Claude Sonnet 4.5

Jan 2025

1.2 yr newer
Gemini 1.5 Flash

Nov 2023

Provider Availability

Claude Sonnet 4.5 is available from Anthropic. Gemini 1.5 Flash is available from Google.

Claude Sonnet 4.5

anthropic logo
Anthropic
Input Price:Input: $3.00/1MOutput Price:Output: $15.00/1M

Gemini 1.5 Flash

google logo
Google
Input Price:Input: $0.15/1MOutput Price:Output: $0.60/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Sonnet 4.5 and Gemini 1.5 Flash side-by-side, then vote on the output you prefer.

Claude Sonnet 4.5
✓ Preferred
Gemini 1.5 Flash
Open in Playground

FAQ

Common questions about Claude Sonnet 4.5 vs Gemini 1.5 Flash.

Which is better, Claude Sonnet 4.5 or Gemini 1.5 Flash?

Claude Sonnet 4.5 leads the LLM Stats Score 32.1 to 6.0. Claude Sonnet 4.5 is made by Anthropic and Gemini 1.5 Flash is made by Google. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Sonnet 4.5 compare to Gemini 1.5 Flash in benchmarks?

Claude Sonnet 4.5 scores MMMLU: 89.1%, AIME 2025: 87.0%, TAU-bench Retail: 86.2%, GPQA: 83.4%, MMMUval: 77.8%. Gemini 1.5 Flash scores XSTest: 97.0%, FLEURS: 90.4%, HellaSwag: 86.5%, GSM8k: 86.2%, BIG-Bench Hard: 85.5%.

Is Claude Sonnet 4.5 cheaper than Gemini 1.5 Flash?

Gemini 1.5 Flash is 20.0x cheaper for input tokens. Claude Sonnet 4.5 costs $3.00/M input and $15.00/M output via anthropic. Gemini 1.5 Flash costs $0.15/M input and $0.60/M output via google.

What are the context window sizes for Claude Sonnet 4.5 and Gemini 1.5 Flash?

Claude Sonnet 4.5 supports 200K tokens and Gemini 1.5 Flash supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Sonnet 4.5 and Gemini 1.5 Flash?

Key differences include LLM Stats Score (32.1 vs 6.0), context window (200K vs 1.0M), input pricing ($3.00 vs $0.15/M). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 4.5 and Gemini 1.5 Flash?

Claude Sonnet 4.5 is developed by Anthropic and Gemini 1.5 Flash is developed by Google.

Related comparisons