Qwen3.5 397B vs LFM2.5-1.2B-Thinking

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

Qwen3.5 397B is clearly ahead on the aggregate, 62 to 33. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Qwen3.5 397B's sharpest advantage is in mathematics, where it averages 81.6 against 42.3. The single biggest benchmark swing on the page is HumanEval, 75 to 17.

LFM2.5-1.2B-Thinking is the reasoning model in the pair, while Qwen3.5 397B is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Qwen3.5 397B gives you the larger context window at 128K, compared with 32K for LFM2.5-1.2B-Thinking.

Quick Verdict

Pick Qwen3.5 397B if you want the stronger benchmark profile. LFM2.5-1.2B-Thinking only becomes the better choice if you want the stronger reasoning-first profile.

Agentic

Qwen3.5 397B

Qwen3.5 397B

56.9

LFM2.5-1.2B-Thinking

34.1

58
Terminal-Bench 2.0
34
62
BrowseComp
37
52
OSWorld-Verified
32

Coding

Qwen3.5 397B

Qwen3.5 397B

40.7

LFM2.5-1.2B-Thinking

8.2

75
HumanEval
17
42
SWE-bench Verified
10
39
LiveCodeBench
9
42
SWE-bench Pro
7

Multimodal & Grounded

Qwen3.5 397B

Qwen3.5 397B

61.4

LFM2.5-1.2B-Thinking

32.4

56
MMMU-Pro
27
68
OfficeQA Pro
39

Reasoning

Qwen3.5 397B

Qwen3.5 397B

75.9

LFM2.5-1.2B-Thinking

38.4

80
SimpleQA
29
78
MuSR
31
82
BBH
67
72
LongBench v2
39
71
MRCRv2
42

Knowledge

Qwen3.5 397B

Qwen3.5 397B

59.3

LFM2.5-1.2B-Thinking

27

83
MMLU
27
82
GPQA
26
80
SuperGPQA
24
78
OpenBookQA
22
73
MMLU-Pro
51
10
HLE
2
71
FrontierScience
31

Instruction Following

Qwen3.5 397B

Qwen3.5 397B

82

LFM2.5-1.2B-Thinking

72

82
IFEval
72

Multilingual

Qwen3.5 397B

Qwen3.5 397B

78.8

LFM2.5-1.2B-Thinking

60.7

82
MGSM
62
77
MMLU-ProX
60

Mathematics

Qwen3.5 397B

Qwen3.5 397B

81.6

LFM2.5-1.2B-Thinking

42.3

83
AIME 2023
28
85
AIME 2024
30
84
AIME 2025
29
79
HMMT Feb 2023
24
81
HMMT Feb 2024
26
80
HMMT Feb 2025
25
82
BRUMO 2025
27
81
MATH-500
61

Frequently Asked Questions

Which is better, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B is ahead overall, 62 to 33. The biggest single separator in this matchup is HumanEval, where the scores are 75 and 17.

Which is better for knowledge tasks, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for knowledge tasks in this comparison, averaging 59.3 versus 27. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for coding in this comparison, averaging 40.7 versus 8.2. Inside this category, HumanEval is the benchmark that creates the most daylight between them.

Which is better for math, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for math in this comparison, averaging 81.6 versus 42.3. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for reasoning in this comparison, averaging 75.9 versus 38.4. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for agentic tasks in this comparison, averaging 56.9 versus 34.1. Inside this category, BrowseComp is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for multimodal and grounded tasks in this comparison, averaging 61.4 versus 32.4. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for instruction following in this comparison, averaging 82 versus 72. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, Qwen3.5 397B or LFM2.5-1.2B-Thinking?

Qwen3.5 397B has the edge for multilingual tasks in this comparison, averaging 78.8 versus 60.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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