GPT-5.3-Codex-Spark vs LFM2.5-1.2B-Thinking

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

GPT-5.3-Codex-Spark is clearly ahead on the aggregate, 87 to 33. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-5.3-Codex-Spark's sharpest advantage is in coding, where it averages 82.3 against 8.2. The single biggest benchmark swing on the page is SWE-bench Pro, 85 to 7.

GPT-5.3-Codex-Spark is also the more expensive model on tokens at $2.00 input / $8.00 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. GPT-5.3-Codex-Spark gives you the larger context window at 256K, compared with 32K for LFM2.5-1.2B-Thinking.

Quick Verdict

Pick GPT-5.3-Codex-Spark if you want the stronger benchmark profile. LFM2.5-1.2B-Thinking only becomes the better choice if you want the cheaper token bill.

Agentic

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

85.6

LFM2.5-1.2B-Thinking

34.1

90
Terminal-Bench 2.0
34
82
BrowseComp
37
83
OSWorld-Verified
32

Coding

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

82.3

LFM2.5-1.2B-Thinking

8.2

91
HumanEval
17
80
SWE-bench Verified
10
80
LiveCodeBench
9
85
SWE-bench Pro
7

Multimodal & Grounded

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

88.3

LFM2.5-1.2B-Thinking

32.4

86
MMMU-Pro
27
91
OfficeQA Pro
39

Reasoning

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

92.7

LFM2.5-1.2B-Thinking

38.4

94
SimpleQA
29
92
MuSR
31
97
BBH
67
91
LongBench v2
39
92
MRCRv2
42

Knowledge

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

78.3

LFM2.5-1.2B-Thinking

27

97
MMLU
27
95
GPQA
26
93
SuperGPQA
24
91
OpenBookQA
22
88
MMLU-Pro
51
42
HLE
2
88
FrontierScience
31

Instruction Following

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

92

LFM2.5-1.2B-Thinking

72

92
IFEval
72

Multilingual

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

90.8

LFM2.5-1.2B-Thinking

60.7

94
MGSM
62
89
MMLU-ProX
60

Mathematics

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

96.7

LFM2.5-1.2B-Thinking

42.3

98
AIME 2023
28
98
AIME 2024
30
97
AIME 2025
29
94
HMMT Feb 2023
24
96
HMMT Feb 2024
26
95
HMMT Feb 2025
25
95
BRUMO 2025
27
98
MATH-500
61

Frequently Asked Questions

Which is better, GPT-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark is ahead overall, 87 to 33. The biggest single separator in this matchup is SWE-bench Pro, where the scores are 85 and 7.

Which is better for knowledge tasks, GPT-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for knowledge tasks in this comparison, averaging 78.3 versus 27. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, GPT-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for coding in this comparison, averaging 82.3 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-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for math in this comparison, averaging 96.7 versus 42.3. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, GPT-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for reasoning in this comparison, averaging 92.7 versus 38.4. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, GPT-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for agentic tasks in this comparison, averaging 85.6 versus 34.1. 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-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for multimodal and grounded tasks in this comparison, averaging 88.3 versus 32.4. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, GPT-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for instruction following in this comparison, averaging 92 versus 72. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, GPT-5.3-Codex-Spark or LFM2.5-1.2B-Thinking?

GPT-5.3-Codex-Spark has the edge for multilingual tasks in this comparison, averaging 90.8 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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