GPT-OSS 120B vs LFM2.5-1.2B-Instruct

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

GPT-OSS 120B is clearly ahead on the aggregate, 48 to 30. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-OSS 120B's sharpest advantage is in reasoning, where it averages 55.2 against 32.1. The single biggest benchmark swing on the page is HumanEval, 43 to 14. LFM2.5-1.2B-Instruct does hit back in instruction following, so the answer changes if that is the part of the workload you care about most.

GPT-OSS 120B gives you the larger context window at 128K, compared with 32K for LFM2.5-1.2B-Instruct.

Quick Verdict

Pick GPT-OSS 120B if you want the stronger benchmark profile. LFM2.5-1.2B-Instruct only becomes the better choice if instruction following is the priority.

Agentic

GPT-OSS 120B

GPT-OSS 120B

44.8

LFM2.5-1.2B-Instruct

25.7

43
Terminal-Bench 2.0
22
50
BrowseComp
31
43
OSWorld-Verified
26

Coding

GPT-OSS 120B

GPT-OSS 120B

28.1

LFM2.5-1.2B-Instruct

7.2

43
HumanEval
14
29
SWE-bench Verified
9
25
LiveCodeBench
8
31
SWE-bench Pro
6

Multimodal & Grounded

GPT-OSS 120B

GPT-OSS 120B

48.8

LFM2.5-1.2B-Instruct

32.4

42
MMMU-Pro
27
57
OfficeQA Pro
39

Reasoning

GPT-OSS 120B

GPT-OSS 120B

55.2

LFM2.5-1.2B-Instruct

32.1

49
SimpleQA
24
47
MuSR
22
73
BBH
59
58
LongBench v2
34
59
MRCRv2
37

Knowledge

GPT-OSS 120B

GPT-OSS 120B

41.5

LFM2.5-1.2B-Instruct

26

51
MMLU
26
50
GPQA
25
48
SuperGPQA
23
46
OpenBookQA
21
63
MMLU-Pro
50
5
HLE
1
49
FrontierScience
30

Instruction Following

LFM2.5-1.2B-Instruct

GPT-OSS 120B

79

LFM2.5-1.2B-Instruct

80

79
IFEval
80

Multilingual

GPT-OSS 120B

GPT-OSS 120B

70.7

LFM2.5-1.2B-Instruct

60.7

72
MGSM
62
70
MMLU-ProX
60

Mathematics

GPT-OSS 120B

GPT-OSS 120B

59.5

LFM2.5-1.2B-Instruct

37

51
AIME 2023
24
53
AIME 2024
26
52
AIME 2025
25
47
HMMT Feb 2023
20
49
HMMT Feb 2024
22
48
HMMT Feb 2025
21
50
BRUMO 2025
23
71
MATH-500
54

Frequently Asked Questions

Which is better, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B is ahead overall, 48 to 30. The biggest single separator in this matchup is HumanEval, where the scores are 43 and 14.

Which is better for knowledge tasks, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B has the edge for knowledge tasks in this comparison, averaging 41.5 versus 26. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B has the edge for coding in this comparison, averaging 28.1 versus 7.2. Inside this category, HumanEval is the benchmark that creates the most daylight between them.

Which is better for math, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B has the edge for math in this comparison, averaging 59.5 versus 37. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B has the edge for reasoning in this comparison, averaging 55.2 versus 32.1. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B has the edge for agentic tasks in this comparison, averaging 44.8 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, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B has the edge for multimodal and grounded tasks in this comparison, averaging 48.8 versus 32.4. Inside this category, OfficeQA Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

LFM2.5-1.2B-Instruct has the edge for instruction following in this comparison, averaging 80 versus 79. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, GPT-OSS 120B or LFM2.5-1.2B-Instruct?

GPT-OSS 120B has the edge for multilingual tasks in this comparison, averaging 70.7 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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