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 48. 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 28.1. The single biggest benchmark swing on the page is MMMU-Pro, 95 to 42.
GPT-5.3 Instant is the reasoning model in the pair, while GPT-OSS 120B 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.
Pick GPT-5.3 Instant if you want the stronger benchmark profile. GPT-OSS 120B only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.
GPT-5.3 Instant
82.9
GPT-OSS 120B
44.8
GPT-5.3 Instant
78.7
GPT-OSS 120B
28.1
GPT-5.3 Instant
95
GPT-OSS 120B
48.8
GPT-5.3 Instant
94.2
GPT-OSS 120B
55.2
GPT-5.3 Instant
80.8
GPT-OSS 120B
41.5
GPT-5.3 Instant
96
GPT-OSS 120B
79
GPT-5.3 Instant
93.4
GPT-OSS 120B
70.7
GPT-5.3 Instant
97.2
GPT-OSS 120B
59.5
GPT-5.3 Instant is ahead overall, 87 to 48. The biggest single separator in this matchup is MMMU-Pro, where the scores are 95 and 42.
GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 41.5. Inside this category, MMLU 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 28.1. Inside this category, SWE-bench Pro 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 59.5. 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 55.2. 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 44.8. 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 48.8. Inside this category, MMMU-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 79. 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 70.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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