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 45. 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 22. The single biggest benchmark swing on the page is SWE-bench Pro, 83 to 22.
GPT-5.3 Instant is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $0.05 input / $0.40 output per 1M tokens for GPT-5 nano. That is roughly 35.0x on output cost alone. GPT-5 nano gives you the larger context window at 400K, compared with 128K for GPT-5.3 Instant.
Pick GPT-5.3 Instant if you want the stronger benchmark profile. GPT-5 nano only becomes the better choice if you want the cheaper token bill or you need the larger 400K context window.
GPT-5.3 Instant
82.9
GPT-5 nano
37.7
GPT-5.3 Instant
78.7
GPT-5 nano
22
GPT-5.3 Instant
95
GPT-5 nano
56.7
GPT-5.3 Instant
94.2
GPT-5 nano
58.8
GPT-5.3 Instant
80.8
GPT-5 nano
63.7
Comparable scores for this category are coming soon. One or both models do not have sourced results here yet.
GPT-5.3 Instant
93.4
GPT-5 nano
48
GPT-5.3 Instant
97.2
GPT-5 nano
85.2
GPT-5.3 Instant is ahead overall, 87 to 45. The biggest single separator in this matchup is SWE-bench Pro, where the scores are 83 and 22.
GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 63.7. Inside this category, FrontierScience 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 22. 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 85.2. Inside this category, AIME 2025 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 58.8. Inside this category, LongBench v2 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 37.7. Inside this category, OSWorld-Verified 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 56.7. Inside this category, OfficeQA Pro 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 48. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.
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