Model Comparison

Kimi K2.5 vs Step-3.5-Flash

Step-3.5-Flash shows notably better performance in the majority of benchmarks. Step-3.5-Flash is 6.1x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

6 benchmarks

Kimi K2.5 outperforms in 2 benchmarks (BrowseComp, SWE-Bench Verified), while Step-3.5-Flash is better at 4 benchmarks (AIME 2025, IMO-AnswerBench, LiveCodeBench v6, Terminal-Bench 2.0).

Step-3.5-Flash shows notably better performance in the majority of benchmarks.

Tue Apr 07 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, Kimi K2.5 ($0.60/1M tokens) is 6.0x more expensive than Step-3.5-Flash ($0.10/1M tokens).

For output processing, Kimi K2.5 ($2.50/1M tokens) is 6.3x more expensive than Step-3.5-Flash ($0.40/1M tokens).

In conclusion, Kimi K2.5 is more expensive than Step-3.5-Flash.*

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

Lowest available price from all providers
Tue Apr 07 2026 • llm-stats.com
Moonshot AI
Kimi K2.5
Input tokens$0.60
Output tokens$2.50
Best providerFireworks
StepFun
Step-3.5-Flash
Input tokens$0.10
Output tokens$0.40
Best providerStepFun
Notice missing or incorrect data?Start an Issue→

Model Size

Parameter count comparison

804.0B diff

Kimi K2.5 has 804.0B more parameters than Step-3.5-Flash, making it 410.2% larger.

Moonshot AI
Kimi K2.5
1000.0Bparameters
StepFun
Step-3.5-Flash
196.0Bparameters
1000.0B
Kimi K2.5
196.0B
Step-3.5-Flash

Context Window

Maximum input and output token capacity

Kimi K2.5 accepts 262,100 input tokens compared to Step-3.5-Flash's 65,536 tokens. Kimi K2.5 can generate longer responses up to 262,100 tokens, while Step-3.5-Flash is limited to 8,192 tokens.

Moonshot AI
Kimi K2.5
Input262,100 tokens
Output262,100 tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Tue Apr 07 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Kimi K2.5 supports multimodal inputs, whereas Step-3.5-Flash does not.

Kimi K2.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Kimi K2.5

Text
Images
Audio
Video

Step-3.5-Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Kimi K2.5 is licensed under MIT, 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.

Kimi K2.5

MIT

Open weights

Step-3.5-Flash

Apache 2.0

Open weights

Release Timeline

When each model was launched

Kimi K2.5 was released on 2026-01-27, while Step-3.5-Flash was released on 2026-02-02.

Step-3.5-Flash is 0 month newer than Kimi K2.5.

Kimi K2.5

Jan 27, 2026

2 months ago

Step-3.5-Flash

Feb 2, 2026

2 months ago

6d newer

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Provider Availability

Kimi K2.5 is available from Fireworks. Step-3.5-Flash is available from StepFun.

Kimi K2.5

fireworks logo
Fireworks
Input Price:Input: $0.60/1MOutput Price:Output: $2.50/1M

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

Moonshot AI
Larger context window (262,100 tokens)
Supports multimodal inputs
Higher BrowseComp score (74.9% vs 69.0%)
Higher SWE-Bench Verified score (76.8% vs 74.4%)
StepFun
Less expensive input tokens
Less expensive output tokens
Higher AIME 2025 score (97.3% vs 96.1%)
Higher IMO-AnswerBench score (85.4% vs 81.8%)
Higher LiveCodeBench v6 score (86.4% vs 85.0%)
Higher Terminal-Bench 2.0 score (51.0% vs 50.8%)

Detailed Comparison

AI Model Comparison Table
Feature
Moonshot AI
Kimi K2.5
StepFun
Step-3.5-Flash

FAQ

Common questions about Kimi K2.5 vs Step-3.5-Flash

Step-3.5-Flash shows notably better performance in the majority of benchmarks. Kimi K2.5 is made by Moonshot AI 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.
Kimi K2.5 scores AIME 2025: 96.1%, HMMT 2025: 95.4%, InfoVQAtest: 92.6%, OCRBench: 92.3%, MathVista-Mini: 90.1%. 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%.
Step-3.5-Flash is 6.0x cheaper for input tokens. Kimi K2.5 costs $0.60/M input and $2.50/M output via fireworks. Step-3.5-Flash costs $0.10/M input and $0.40/M output via stepfun.
Kimi K2.5 supports 262K 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.
Key differences include context window (262K vs 66K), input pricing ($0.60 vs $0.10/M), multimodal support (yes vs no), licensing (MIT vs Apache 2.0). See the full comparison above for benchmark-by-benchmark results.
Kimi K2.5 is developed by Moonshot AI and Step-3.5-Flash is developed by StepFun.