Claude Sonnet 4.6 vs LFM2.5-1.2B-Thinking

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

Claude Sonnet 4.6 is clearly ahead on the aggregate, 78 to 33. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Sonnet 4.6's sharpest advantage is in multimodal & grounded, where it averages 91.9 against 32.4. The single biggest benchmark swing on the page is HumanEval, 93 to 17.

Claude Sonnet 4.6 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for LFM2.5-1.2B-Thinking. That is roughly Infinityx on output cost alone. LFM2.5-1.2B-Thinking is the reasoning model in the pair, while Claude Sonnet 4.6 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. Claude Sonnet 4.6 gives you the larger context window at 200K, compared with 32K for LFM2.5-1.2B-Thinking.

Quick Verdict

Pick Claude Sonnet 4.6 if you want the stronger benchmark profile. LFM2.5-1.2B-Thinking only becomes the better choice if you want the cheaper token bill or you want the stronger reasoning-first profile.

Agentic

Claude Sonnet 4.6

Claude Sonnet 4.6

71.1

LFM2.5-1.2B-Thinking

34.1

70
Terminal-Bench 2.0
34
77
BrowseComp
37
68
OSWorld-Verified
32

Coding

Claude Sonnet 4.6

Claude Sonnet 4.6

60

LFM2.5-1.2B-Thinking

8.2

93
HumanEval
17
69
SWE-bench Verified
10
54
LiveCodeBench
9
64
SWE-bench Pro
7

Multimodal & Grounded

Claude Sonnet 4.6

Claude Sonnet 4.6

91.9

LFM2.5-1.2B-Thinking

32.4

95
MMMU-Pro
27
88
OfficeQA Pro
39

Reasoning

Claude Sonnet 4.6

Claude Sonnet 4.6

87.6

LFM2.5-1.2B-Thinking

38.4

95
SimpleQA
29
93
MuSR
31
88
BBH
67
83
LongBench v2
39
79
MRCRv2
42

Knowledge

Claude Sonnet 4.6

Claude Sonnet 4.6

71.8

LFM2.5-1.2B-Thinking

27

99
MMLU
27
97
GPQA
26
95
SuperGPQA
24
93
OpenBookQA
22
83
MMLU-Pro
51
21
HLE
2
85
FrontierScience
31

Instruction Following

Claude Sonnet 4.6

Claude Sonnet 4.6

91

LFM2.5-1.2B-Thinking

72

91
IFEval
72

Multilingual

Claude Sonnet 4.6

Claude Sonnet 4.6

89.7

LFM2.5-1.2B-Thinking

60.7

91
MGSM
62
89
MMLU-ProX
60

Mathematics

Claude Sonnet 4.6

Claude Sonnet 4.6

94.1

LFM2.5-1.2B-Thinking

42.3

99
AIME 2023
28
99
AIME 2024
30
98
AIME 2025
29
95
HMMT Feb 2023
24
97
HMMT Feb 2024
26
96
HMMT Feb 2025
25
96
BRUMO 2025
27
91
MATH-500
61

Frequently Asked Questions

Which is better, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 is ahead overall, 78 to 33. The biggest single separator in this matchup is HumanEval, where the scores are 93 and 17.

Which is better for knowledge tasks, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for knowledge tasks in this comparison, averaging 71.8 versus 27. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for coding in this comparison, averaging 60 versus 8.2. Inside this category, HumanEval is the benchmark that creates the most daylight between them.

Which is better for math, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for math in this comparison, averaging 94.1 versus 42.3. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for reasoning in this comparison, averaging 87.6 versus 38.4. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for agentic tasks in this comparison, averaging 71.1 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, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for multimodal and grounded tasks in this comparison, averaging 91.9 versus 32.4. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for instruction following in this comparison, averaging 91 versus 72. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, Claude Sonnet 4.6 or LFM2.5-1.2B-Thinking?

Claude Sonnet 4.6 has the edge for multilingual tasks in this comparison, averaging 89.7 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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