Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
GPT-5.1 is clearly ahead on the aggregate, 80 to 65. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.1's sharpest advantage is in coding, where it averages 66.2 against 42.4. The single biggest benchmark swing on the page is AIME 2023, 99 to 72.
GPT-5.1 is also the more expensive model on tokens at $1.50 input / $6.00 output per 1M tokens, versus $0.25 input / $2.00 output per 1M tokens for Seed 1.6. That is roughly 3.0x on output cost alone. Seed 1.6 gives you the larger context window at 256K, compared with 200K for GPT-5.1.
Pick GPT-5.1 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-5.1
75.8
Seed 1.6
62.3
GPT-5.1
66.2
Seed 1.6
42.4
GPT-5.1
91.8
Seed 1.6
79.6
GPT-5.1
88.4
Seed 1.6
74.5
GPT-5.1
72.5
Seed 1.6
56.4
GPT-5.1
89
Seed 1.6
87
GPT-5.1
87.7
Seed 1.6
83.4
GPT-5.1
95.4
Seed 1.6
75.9
GPT-5.1 is ahead overall, 80 to 65. The biggest single separator in this matchup is AIME 2023, where the scores are 99 and 72.
GPT-5.1 has the edge for knowledge tasks in this comparison, averaging 72.5 versus 56.4. Inside this category, MMLU is the benchmark that creates the most daylight between them.
GPT-5.1 has the edge for coding in this comparison, averaging 66.2 versus 42.4. Inside this category, HumanEval is the benchmark that creates the most daylight between them.
GPT-5.1 has the edge for math in this comparison, averaging 95.4 versus 75.9. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
GPT-5.1 has the edge for reasoning in this comparison, averaging 88.4 versus 74.5. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.
GPT-5.1 has the edge for agentic tasks in this comparison, averaging 75.8 versus 62.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
GPT-5.1 has the edge for multimodal and grounded tasks in this comparison, averaging 91.8 versus 79.6. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
GPT-5.1 has the edge for instruction following in this comparison, averaging 89 versus 87. Inside this category, IFEval is the benchmark that creates the most daylight between them.
GPT-5.1 has the edge for multilingual tasks in this comparison, averaging 87.7 versus 83.4. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.
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