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 65. 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 42.4. The single biggest benchmark swing on the page is LiveCodeBench, 75 to 38.
GPT-5.3 Instant is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $0.25 input / $2.00 output per 1M tokens for Seed 1.6. That is roughly 7.0x on output cost alone. Seed 1.6 gives you the larger context window at 256K, compared with 128K for GPT-5.3 Instant.
Pick GPT-5.3 Instant if you want the stronger benchmark profile. Seed 1.6 only becomes the better choice if you want the cheaper token bill or you need the larger 256K context window.
GPT-5.3 Instant
82.9
Seed 1.6
62.3
GPT-5.3 Instant
78.7
Seed 1.6
42.4
GPT-5.3 Instant
95
Seed 1.6
79.6
GPT-5.3 Instant
94.2
Seed 1.6
74.5
GPT-5.3 Instant
80.8
Seed 1.6
56.4
GPT-5.3 Instant
96
Seed 1.6
87
GPT-5.3 Instant
93.4
Seed 1.6
83.4
GPT-5.3 Instant
97.2
Seed 1.6
75.9
GPT-5.3 Instant is ahead overall, 87 to 65. The biggest single separator in this matchup is LiveCodeBench, where the scores are 75 and 38.
GPT-5.3 Instant has the edge for knowledge tasks in this comparison, averaging 80.8 versus 56.4. 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 42.4. Inside this category, LiveCodeBench 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 75.9. 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 74.5. 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 62.3. 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 79.6. 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 87. 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 83.4. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.
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