Claude Sonnet 4.5 vs LFM2.5-1.2B-Instruct

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

Claude Sonnet 4.5 is clearly ahead on the aggregate, 76 to 30. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Claude Sonnet 4.5's sharpest advantage is in multimodal & grounded, where it averages 91.4 against 32.4. The single biggest benchmark swing on the page is HumanEval, 87 to 14.

Claude Sonnet 4.5 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-Instruct. That is roughly Infinityx on output cost alone. Claude Sonnet 4.5 gives you the larger context window at 200K, compared with 32K for LFM2.5-1.2B-Instruct.

Quick Verdict

Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. LFM2.5-1.2B-Instruct only becomes the better choice if you want the cheaper token bill.

Agentic

Claude Sonnet 4.5

Claude Sonnet 4.5

70.3

LFM2.5-1.2B-Instruct

25.7

69
Terminal-Bench 2.0
22
74
BrowseComp
31
69
OSWorld-Verified
26

Coding

Claude Sonnet 4.5

Claude Sonnet 4.5

57.5

LFM2.5-1.2B-Instruct

7.2

87
HumanEval
14
66
SWE-bench Verified
9
53
LiveCodeBench
8
60
SWE-bench Pro
6

Multimodal & Grounded

Claude Sonnet 4.5

Claude Sonnet 4.5

91.4

LFM2.5-1.2B-Instruct

32.4

95
MMMU-Pro
27
87
OfficeQA Pro
39

Reasoning

Claude Sonnet 4.5

Claude Sonnet 4.5

86

LFM2.5-1.2B-Instruct

32.1

91
SimpleQA
24
89
MuSR
22
88
BBH
59
82
LongBench v2
34
81
MRCRv2
37

Knowledge

Claude Sonnet 4.5

Claude Sonnet 4.5

70.7

LFM2.5-1.2B-Instruct

26

95
MMLU
26
93
GPQA
25
91
SuperGPQA
23
89
OpenBookQA
21
84
MMLU-Pro
50
21
HLE
1
84
FrontierScience
30

Instruction Following

Claude Sonnet 4.5

Claude Sonnet 4.5

90

LFM2.5-1.2B-Instruct

80

90
IFEval
80

Multilingual

Claude Sonnet 4.5

Claude Sonnet 4.5

88.4

LFM2.5-1.2B-Instruct

60.7

91
MGSM
62
87
MMLU-ProX
60

Mathematics

Claude Sonnet 4.5

Claude Sonnet 4.5

92.4

LFM2.5-1.2B-Instruct

37

97
AIME 2023
24
99
AIME 2024
26
98
AIME 2025
25
93
HMMT Feb 2023
20
95
HMMT Feb 2024
22
94
HMMT Feb 2025
21
96
BRUMO 2025
23
88
MATH-500
54

Frequently Asked Questions

Which is better, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 is ahead overall, 76 to 30. The biggest single separator in this matchup is HumanEval, where the scores are 87 and 14.

Which is better for knowledge tasks, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 70.7 versus 26. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for coding in this comparison, averaging 57.5 versus 7.2. Inside this category, HumanEval is the benchmark that creates the most daylight between them.

Which is better for math, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for math in this comparison, averaging 92.4 versus 37. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for reasoning in this comparison, averaging 86 versus 32.1. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for agentic tasks in this comparison, averaging 70.3 versus 25.7. 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, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for multimodal and grounded tasks in this comparison, averaging 91.4 versus 32.4. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for instruction following in this comparison, averaging 90 versus 80. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, Claude Sonnet 4.5 or LFM2.5-1.2B-Instruct?

Claude Sonnet 4.5 has the edge for multilingual tasks in this comparison, averaging 88.4 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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