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 51. 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 19. The single biggest benchmark swing on the page is SWE-bench Verified, 76 to 10.
GPT-5.3 Instant is the reasoning model in the pair, while Claude 3 Opus 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. Claude 3 Opus gives you the larger context window at 200K, compared with 128K for GPT-5.3 Instant.
Pick GPT-5.3 Instant if you want the stronger benchmark profile. Claude 3 Opus only becomes the better choice if you need the larger 200K context window or you would rather avoid the extra latency and token burn of a reasoning model.
GPT-5.3 Instant
82.9
Claude 3 Opus
48.1
GPT-5.3 Instant
78.7
Claude 3 Opus
19
GPT-5.3 Instant
95
Claude 3 Opus
70.3
GPT-5.3 Instant
94.2
Claude 3 Opus
61.6
GPT-5.3 Instant
80.8
Claude 3 Opus
45
GPT-5.3 Instant
96
Claude 3 Opus
77
GPT-5.3 Instant
93.4
Claude 3 Opus
69.8
GPT-5.3 Instant
97.2
Claude 3 Opus
65.9
GPT-5.3 Instant is ahead overall, 87 to 51. The biggest single separator in this matchup is SWE-bench Verified, where the scores are 76 and 10.
GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 45. 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 19. 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 65.9. 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 61.6. 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 48.1. 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 70.3. 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 69.8. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.
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