GPT-4.1 nano vs LFM2.5-1.2B-Thinking

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

GPT-4.1 nano is clearly ahead on the aggregate, 49 to 33. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-4.1 nano's sharpest advantage is in reasoning, where it averages 74.1 against 38.4. The single biggest benchmark swing on the page is MMLU, 80.1 to 27. LFM2.5-1.2B-Thinking does hit back in mathematics, so the answer changes if that is the part of the workload you care about most.

GPT-4.1 nano is also the more expensive model on tokens at $0.10 input / $0.40 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 GPT-4.1 nano 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. GPT-4.1 nano gives you the larger context window at 1M, compared with 32K for LFM2.5-1.2B-Thinking.

Quick Verdict

Pick GPT-4.1 nano if you want the stronger benchmark profile. LFM2.5-1.2B-Thinking only becomes the better choice if mathematics is the priority or you want the cheaper token bill.

Agentic

GPT-4.1 nano

GPT-4.1 nano

47.4

LFM2.5-1.2B-Thinking

34.1

43
Terminal-Bench 2.0
34
62
BrowseComp
37
42
OSWorld-Verified
32

Coding

GPT-4.1 nano

GPT-4.1 nano

18

LFM2.5-1.2B-Thinking

8.2

18
SWE-bench Pro
7
Coming soon
HumanEval
17
Coming soon
SWE-bench Verified
10
Coming soon
LiveCodeBench
9

Multimodal & Grounded

GPT-4.1 nano

GPT-4.1 nano

59.3

LFM2.5-1.2B-Thinking

32.4

53
MMMU-Pro
27
67
OfficeQA Pro
39

Reasoning

GPT-4.1 nano

GPT-4.1 nano

74.1

LFM2.5-1.2B-Thinking

38.4

75
LongBench v2
39
73
MRCRv2
42
Coming soon
SimpleQA
29
Coming soon
MuSR
31
Coming soon
BBH
67

Knowledge

GPT-4.1 nano

GPT-4.1 nano

50.7

LFM2.5-1.2B-Thinking

27

80.1
MMLU
27
50.3
GPQA
26
51
FrontierScience
31
Coming soon
SuperGPQA
24
Coming soon
OpenBookQA
22
Coming soon
MMLU-Pro
51
Coming soon
HLE
2

Instruction Following

GPT-4.1 nano

GPT-4.1 nano

83.2

LFM2.5-1.2B-Thinking

72

83.2
IFEval
72

Multilingual

LFM2.5-1.2B-Thinking

GPT-4.1 nano

59

LFM2.5-1.2B-Thinking

60.7

59
MMLU-ProX
60
Coming soon
MGSM
62

Mathematics

LFM2.5-1.2B-Thinking

GPT-4.1 nano

9.8

LFM2.5-1.2B-Thinking

42.3

9.8
AIME 2024
30
Coming soon
AIME 2023
28
Coming soon
AIME 2025
29
Coming soon
HMMT Feb 2023
24
Coming soon
HMMT Feb 2024
26
Coming soon
HMMT Feb 2025
25
Coming soon
BRUMO 2025
27
Coming soon
MATH-500
61

Frequently Asked Questions

Which is better, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

GPT-4.1 nano is ahead overall, 49 to 33. The biggest single separator in this matchup is MMLU, where the scores are 80.1 and 27.

Which is better for knowledge tasks, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

GPT-4.1 nano has the edge for knowledge tasks in this comparison, averaging 50.7 versus 27. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

GPT-4.1 nano has the edge for coding in this comparison, averaging 18 versus 8.2. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.

Which is better for math, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

LFM2.5-1.2B-Thinking has the edge for math in this comparison, averaging 42.3 versus 9.8. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.

Which is better for reasoning, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

GPT-4.1 nano has the edge for reasoning in this comparison, averaging 74.1 versus 38.4. Inside this category, LongBench v2 is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

GPT-4.1 nano has the edge for agentic tasks in this comparison, averaging 47.4 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, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

GPT-4.1 nano has the edge for multimodal and grounded tasks in this comparison, averaging 59.3 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-4.1 nano or LFM2.5-1.2B-Thinking?

GPT-4.1 nano has the edge for instruction following in this comparison, averaging 83.2 versus 72. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, GPT-4.1 nano or LFM2.5-1.2B-Thinking?

LFM2.5-1.2B-Thinking has the edge for multilingual tasks in this comparison, averaging 60.7 versus 59. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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