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 76. 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 59.5. The single biggest benchmark swing on the page is LiveCodeBench, 80 to 54.
GPT-5.3-Codex-Spark is the reasoning model in the pair, while Grok 4.1 Fast 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. Grok 4.1 Fast gives you the larger context window at 1M, compared with 256K for GPT-5.3-Codex-Spark.
Pick GPT-5.3-Codex-Spark if you want the stronger benchmark profile. Grok 4.1 Fast only becomes the better choice if you need the larger 1M context window or you would rather avoid the extra latency and token burn of a reasoning model.
GPT-5.3-Codex-Spark
85.6
Grok 4.1 Fast
71
GPT-5.3-Codex-Spark
82.3
Grok 4.1 Fast
59.5
GPT-5.3-Codex-Spark
88.3
Grok 4.1 Fast
87.4
GPT-5.3-Codex-Spark
92.7
Grok 4.1 Fast
88.3
GPT-5.3-Codex-Spark
78.3
Grok 4.1 Fast
69.2
GPT-5.3-Codex-Spark
92
Grok 4.1 Fast
90
GPT-5.3-Codex-Spark
90.8
Grok 4.1 Fast
84.8
GPT-5.3-Codex-Spark
96.7
Grok 4.1 Fast
92.3
GPT-5.3-Codex-Spark is ahead overall, 87 to 76. The biggest single separator in this matchup is LiveCodeBench, where the scores are 80 and 54.
GPT-5.3-Codex-Spark has the edge for knowledge tasks in this comparison, averaging 78.3 versus 69.2. Inside this category, HLE is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for coding in this comparison, averaging 82.3 versus 59.5. Inside this category, LiveCodeBench is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for math in this comparison, averaging 96.7 versus 92.3. Inside this category, MATH-500 is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for reasoning in this comparison, averaging 92.7 versus 88.3. Inside this category, BBH is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for agentic tasks in this comparison, averaging 85.6 versus 71. Inside this category, OSWorld-Verified is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for multimodal and grounded tasks in this comparison, averaging 88.3 versus 87.4. Inside this category, OfficeQA Pro is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for instruction following in this comparison, averaging 92 versus 90. Inside this category, IFEval is the benchmark that creates the most daylight between them.
GPT-5.3-Codex-Spark has the edge for multilingual tasks in this comparison, averaging 90.8 versus 84.8. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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