GPT-5.3-Codex-Spark vs o3-pro

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 71. 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 49.2. The single biggest benchmark swing on the page is LiveCodeBench, 80 to 44.

GPT-5.3-Codex-Spark gives you the larger context window at 256K, compared with 200K for o3-pro.

Quick Verdict

Pick GPT-5.3-Codex-Spark if you want the stronger benchmark profile. o3-pro only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.

Agentic

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

85.6

o3-pro

70.4

90
Terminal-Bench 2.0
69
82
BrowseComp
76
83
OSWorld-Verified
68

Coding

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

82.3

o3-pro

49.2

91
HumanEval
80
80
SWE-bench Verified
46
80
LiveCodeBench
44
85
SWE-bench Pro
55

Multimodal & Grounded

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

88.3

o3-pro

74.1

86
MMMU-Pro
70
91
OfficeQA Pro
79

Reasoning

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

92.7

o3-pro

83.6

94
SimpleQA
86
92
MuSR
84
97
BBH
89
91
LongBench v2
81
92
MRCRv2
81

Knowledge

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

78.3

o3-pro

67.1

97
MMLU
88
95
GPQA
89
93
SuperGPQA
87
91
OpenBookQA
85
88
MMLU-Pro
75
42
HLE
26
88
FrontierScience
77

Instruction Following

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

92

o3-pro

82

92
IFEval
82

Multilingual

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

90.8

o3-pro

81.1

94
MGSM
83
89
MMLU-ProX
80

Mathematics

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

96.7

o3-pro

89

98
AIME 2023
90
98
AIME 2024
92
97
AIME 2025
91
94
HMMT Feb 2023
86
96
HMMT Feb 2024
88
95
HMMT Feb 2025
87
95
BRUMO 2025
89
98
MATH-500
89

Frequently Asked Questions

Which is better, GPT-5.3-Codex-Spark or o3-pro?

GPT-5.3-Codex-Spark is ahead overall, 87 to 71. The biggest single separator in this matchup is LiveCodeBench, where the scores are 80 and 44.

Which is better for knowledge tasks, GPT-5.3-Codex-Spark or o3-pro?

GPT-5.3-Codex-Spark has the edge for knowledge tasks in this comparison, averaging 78.3 versus 67.1. Inside this category, HLE is the benchmark that creates the most daylight between them.

Which is better for coding, GPT-5.3-Codex-Spark or o3-pro?

GPT-5.3-Codex-Spark has the edge for coding in this comparison, averaging 82.3 versus 49.2. Inside this category, LiveCodeBench is the benchmark that creates the most daylight between them.

Which is better for math, GPT-5.3-Codex-Spark or o3-pro?

GPT-5.3-Codex-Spark has the edge for math in this comparison, averaging 96.7 versus 89. Inside this category, MATH-500 is the benchmark that creates the most daylight between them.

Which is better for reasoning, GPT-5.3-Codex-Spark or o3-pro?

GPT-5.3-Codex-Spark has the edge for reasoning in this comparison, averaging 92.7 versus 83.6. Inside this category, MRCRv2 is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, GPT-5.3-Codex-Spark or o3-pro?

GPT-5.3-Codex-Spark has the edge for agentic tasks in this comparison, averaging 85.6 versus 70.4. 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 o3-pro?

GPT-5.3-Codex-Spark has the edge for multimodal and grounded tasks in this comparison, averaging 88.3 versus 74.1. 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 o3-pro?

GPT-5.3-Codex-Spark has the edge for instruction following in this comparison, averaging 92 versus 82. 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 o3-pro?

GPT-5.3-Codex-Spark has the edge for multilingual tasks in this comparison, averaging 90.8 versus 81.1. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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