Model Comparison

Claude Opus 4.5 vs Step-3.5-FlashWhich is better in 2026?

Claude Opus 4.5 significantly outperforms across most benchmarks. Step-3.5-Flash is 57.1x cheaper per token.

Verdict: Claude Opus 4.5 vs Step-3.5-Flash — which is better?

Claude Opus 4.5 (by Anthropic) and Step-3.5-Flash (by StepFun) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

Claude Opus 4.5 outperforms in 2 benchmarks (SWE-Bench Verified, Terminal-Bench 2.0), while Step-3.5-Flash is better at 0 benchmarks. Claude Opus 4.5 significantly outperforms across most benchmarks.

On price, Step-3.5-Flash is roughly 57.1x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Claude Opus 4.5 also accepts a larger context window (200,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Claude Opus 4.5 if…

  • you want the strongest raw capability — it leads on 2 of 2 shared benchmarks
  • you process long inputs — it offers a 200,000 token context window

Choose Step-3.5-Flash if…

  • cost matters — it's about 57.1x cheaper per token
  • you want the most recent training data — it shipped Feb 2026
  • you need open weights you can self-host or fine-tune

Performance Benchmarks

Comparative analysis across standard metrics

2 benchmarks

Claude Opus 4.5 outperforms in 2 benchmarks (SWE-Bench Verified, Terminal-Bench 2.0), while Step-3.5-Flash is better at 0 benchmarks.

Claude Opus 4.5 significantly outperforms across most benchmarks.

Sun Jun 28 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Step-3.5-Flash costs less

For input processing, Claude Opus 4.5 ($5.00/1M tokens) is 50.0x more expensive than Step-3.5-Flash ($0.10/1M tokens).

For output processing, Claude Opus 4.5 ($25.00/1M tokens) is 62.5x more expensive than Step-3.5-Flash ($0.40/1M tokens).

In conclusion, Claude Opus 4.5 is more expensive than Step-3.5-Flash.*

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

Lowest available price from all providers
Sun Jun 28 2026 • llm-stats.com
Anthropic
Claude Opus 4.5
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
StepFun
Step-3.5-Flash
Input tokens$0.10
Output tokens$0.40
Best providerStepFun
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Claude Opus 4.5 accepts 200,000 input tokens compared to Step-3.5-Flash's 65,536 tokens. Claude Opus 4.5 can generate longer responses up to 64,000 tokens, while Step-3.5-Flash is limited to 8,192 tokens.

Anthropic
Claude Opus 4.5
Input200,000 tokens
Output64,000 tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Sun Jun 28 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Claude Opus 4.5 supports multimodal inputs, whereas Step-3.5-Flash does not.

Claude Opus 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Opus 4.5

Text
Images
Audio
Video

Step-3.5-Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Opus 4.5 is licensed under a proprietary license, while Step-3.5-Flash uses Apache 2.0.

License differences may affect how you can use these models in commercial or open-source projects.

Claude Opus 4.5

Proprietary

Closed source

Step-3.5-Flash

Apache 2.0

Open weights

Release Timeline

When each model was launched

Claude Opus 4.5 was released on 2025-11-24, while Step-3.5-Flash was released on 2026-02-02.

Step-3.5-Flash is 2 months newer than Claude Opus 4.5.

Claude Opus 4.5

Nov 24, 2025

7 months ago

Step-3.5-Flash

Feb 2, 2026

4 months ago

2mo newer

Knowledge Cutoff

When training data ends

Claude Opus 4.5 has a documented knowledge cutoff of 2025-03-31, while Step-3.5-Flash's cutoff date is not specified.

We can confirm Claude Opus 4.5's training data extends to 2025-03-31, but cannot make a direct comparison without Step-3.5-Flash's cutoff date.

Claude Opus 4.5

Mar 2025

Step-3.5-Flash

—

Provider Availability

Claude Opus 4.5 is available from Anthropic. Step-3.5-Flash is available from StepFun.

Claude Opus 4.5

anthropic logo
Anthropic
Input Price:Input: $5.00/1MOutput Price:Output: $25.00/1M

Step-3.5-Flash

stepfun logo
StepFun
Input Price:Input: $0.10/1MOutput Price:Output: $0.40/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Anthropic
Larger context window (200,000 tokens)
Supports multimodal inputs
Higher SWE-Bench Verified score (80.9% vs 74.4%)
Higher Terminal-Bench 2.0 score (59.3% vs 51.0%)
StepFun
Less expensive input tokens
Less expensive output tokens
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Claude Opus 4.5 and Step-3.5-Flash side-by-side, then vote on the output you prefer.

Claude Opus 4.5
✓ Preferred
Step-3.5-Flash
Open in Playground
AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.5
StepFun
Step-3.5-Flash

FAQ

Common questions about Claude Opus 4.5 vs Step-3.5-Flash.

Which is better, Claude Opus 4.5 or Step-3.5-Flash?

Claude Opus 4.5 significantly outperforms across most benchmarks. Claude Opus 4.5 is made by Anthropic and Step-3.5-Flash is made by StepFun. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Claude Opus 4.5 compare to Step-3.5-Flash in benchmarks?

Claude Opus 4.5 scores Tau2 Telecom: 98.2%, MMMLU: 90.8%, Tau2 Retail: 88.9%, GPQA: 87.0%, SWE-Bench Verified: 80.9%. Step-3.5-Flash scores AIME 2025: 97.3%, Tau-bench: 88.2%, LiveCodeBench v6: 86.4%, IMO-AnswerBench: 85.4%, SWE-Bench Verified: 74.4%.

Is Claude Opus 4.5 cheaper than Step-3.5-Flash?

Step-3.5-Flash is 50.0x cheaper for input tokens. Claude Opus 4.5 costs $5.00/M input and $25.00/M output via anthropic. Step-3.5-Flash costs $0.10/M input and $0.40/M output via stepfun.

What are the context window sizes for Claude Opus 4.5 and Step-3.5-Flash?

Claude Opus 4.5 supports 200K tokens and Step-3.5-Flash supports 66K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Opus 4.5 and Step-3.5-Flash?

Key differences include context window (200K vs 66K), input pricing ($5.00 vs $0.10/M), multimodal support (yes vs no), licensing (Proprietary vs Apache 2.0). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Opus 4.5 and Step-3.5-Flash?

Claude Opus 4.5 is developed by Anthropic and Step-3.5-Flash is developed by StepFun.

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