Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
GPT-5.3 Instant is clearly ahead on the aggregate, 87 to 52. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.3 Instant's sharpest advantage is in coding, where it averages 78.7 against 18.5. The single biggest benchmark swing on the page is SWE-bench Verified, 76 to 5.
GPT-5.3 Instant is the reasoning model in the pair, while Gemini 1.5 Pro 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. Gemini 1.5 Pro gives you the larger context window at 2M, compared with 128K for GPT-5.3 Instant.
Pick GPT-5.3 Instant if you want the stronger benchmark profile. Gemini 1.5 Pro only becomes the better choice if you need the larger 2M context window or you would rather avoid the extra latency and token burn of a reasoning model.
GPT-5.3 Instant
82.9
Gemini 1.5 Pro
49.8
GPT-5.3 Instant
78.7
Gemini 1.5 Pro
18.5
GPT-5.3 Instant
95
Gemini 1.5 Pro
74.1
GPT-5.3 Instant
94.2
Gemini 1.5 Pro
66.9
GPT-5.3 Instant
80.8
Gemini 1.5 Pro
44.2
GPT-5.3 Instant
96
Gemini 1.5 Pro
77
GPT-5.3 Instant
93.4
Gemini 1.5 Pro
69.5
GPT-5.3 Instant
97.2
Gemini 1.5 Pro
67.5
GPT-5.3 Instant is ahead overall, 87 to 52. The biggest single separator in this matchup is SWE-bench Verified, where the scores are 76 and 5.
GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 44.2. Inside this category, HLE is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for coding in this comparison, averaging 78.7 versus 18.5. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for math in this comparison, averaging 97.2 versus 67.5. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for reasoning in this comparison, averaging 94.2 versus 66.9. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for agentic tasks in this comparison, averaging 82.9 versus 49.8. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for multimodal and grounded tasks in this comparison, averaging 95 versus 74.1. Inside this category, OfficeQA Pro is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for instruction following in this comparison, averaging 96 versus 77. Inside this category, IFEval is the benchmark that creates the most daylight between them.
GPT-5.3 Instant has the edge for multilingual tasks in this comparison, averaging 93.4 versus 69.5. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.
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