Step 3.5 Flash vs Kimi K2.5

Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.

Step 3.5 Flash is clearly ahead on the aggregate, 66 to 60. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Step 3.5 Flash's sharpest advantage is in coding, where it averages 47.1 against 38.9. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 62 to 51.

Kimi K2.5 is also the more expensive model on tokens at $0.50 input / $2.80 output per 1M tokens, versus $0.10 input / $0.30 output per 1M tokens for Step 3.5 Flash. That is roughly 9.3x on output cost alone. Step 3.5 Flash gives you the larger context window at 256K, compared with 128K for Kimi K2.5.

Quick Verdict

Pick Step 3.5 Flash if you want the stronger benchmark profile. Kimi K2.5 only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.

Agentic

Step 3.5 Flash

Step 3.5 Flash

60.2

Kimi K2.5

52.3

62
Terminal-Bench 2.0
51
66
BrowseComp
59
54
OSWorld-Verified
49

Coding

Step 3.5 Flash

Step 3.5 Flash

47.1

Kimi K2.5

38.9

77
HumanEval
69
48
SWE-bench Verified
42
45
LiveCodeBench
37
49
SWE-bench Pro
40

Multimodal & Grounded

Step 3.5 Flash

Step 3.5 Flash

66.7

Kimi K2.5

64.6

64
MMMU-Pro
61
70
OfficeQA Pro
69

Reasoning

Step 3.5 Flash

Step 3.5 Flash

78.3

Kimi K2.5

71.7

82
SimpleQA
74
82
MuSR
72
83
BBH
81
74
LongBench v2
67
73
MRCRv2
70

Knowledge

Step 3.5 Flash

Step 3.5 Flash

60.8

Kimi K2.5

57.2

84
MMLU
77
83
GPQA
76
81
SuperGPQA
74
79
OpenBookQA
72
76
MMLU-Pro
74
12
HLE
11
71
FrontierScience
67

Instruction Following

Step 3.5 Flash

Step 3.5 Flash

87

Kimi K2.5

85

87
IFEval
85

Multilingual

Step 3.5 Flash

Step 3.5 Flash

82.8

Kimi K2.5

79.8

86
MGSM
83
81
MMLU-ProX
78

Mathematics

Step 3.5 Flash

Step 3.5 Flash

84.5

Kimi K2.5

78.7

85
AIME 2023
77
87
AIME 2024
79
86
AIME 2025
78
81
HMMT Feb 2023
73
83
HMMT Feb 2024
75
82
HMMT Feb 2025
74
84
BRUMO 2025
76
85
MATH-500
82

Frequently Asked Questions

Which is better, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash is ahead overall, 66 to 60. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 62 and 51.

Which is better for knowledge tasks, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 57.2. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 38.9. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.

Which is better for math, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 78.7. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 71.7. Inside this category, MuSR is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 52.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 66.7 versus 64.6. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for instruction following in this comparison, averaging 87 versus 85. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, Step 3.5 Flash or Kimi K2.5?

Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 79.8. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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