Seed 1.6 Flash vs GPT-OSS 120B

Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.

Seed 1.6 Flash is clearly ahead on the aggregate, 56 to 48. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Seed 1.6 Flash's sharpest advantage is in multimodal & grounded, where it averages 73.1 against 48.8. The single biggest benchmark swing on the page is MMMU-Pro, 74 to 42. GPT-OSS 120B does hit back in coding, so the answer changes if that is the part of the workload you care about most.

Seed 1.6 Flash 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. Seed 1.6 Flash gives you the larger context window at 256K, compared with 128K for GPT-OSS 120B.

Quick Verdict

Pick Seed 1.6 Flash if you want the stronger benchmark profile. GPT-OSS 120B only becomes the better choice if coding is the priority or you would rather avoid the extra latency and token burn of a reasoning model.

Agentic

Seed 1.6 Flash

Seed 1.6 Flash

54.5

GPT-OSS 120B

44.8

52
Terminal-Bench 2.0
43
62
BrowseComp
50
52
OSWorld-Verified
43

Coding

GPT-OSS 120B

Seed 1.6 Flash

27.6

GPT-OSS 120B

28.1

59
HumanEval
43
24
SWE-bench Verified
29
25
LiveCodeBench
25
31
SWE-bench Pro
31

Multimodal & Grounded

Seed 1.6 Flash

Seed 1.6 Flash

73.1

GPT-OSS 120B

48.8

74
MMMU-Pro
42
72
OfficeQA Pro
57

Reasoning

Seed 1.6 Flash

Seed 1.6 Flash

66.8

GPT-OSS 120B

55.2

61
SimpleQA
49
59
MuSR
47
75
BBH
73
70
LongBench v2
58
74
MRCRv2
59

Knowledge

Seed 1.6 Flash

Seed 1.6 Flash

47.3

GPT-OSS 120B

41.5

65
MMLU
51
64
GPQA
50
62
SuperGPQA
48
60
OpenBookQA
46
65
MMLU-Pro
63
3
HLE
5
57
FrontierScience
49

Instruction Following

Seed 1.6 Flash

Seed 1.6 Flash

81

GPT-OSS 120B

79

81
IFEval
79

Multilingual

Seed 1.6 Flash

Seed 1.6 Flash

72.8

GPT-OSS 120B

70.7

76
MGSM
72
71
MMLU-ProX
70

Mathematics

Seed 1.6 Flash

Seed 1.6 Flash

67.1

GPT-OSS 120B

59.5

64
AIME 2023
51
66
AIME 2024
53
65
AIME 2025
52
60
HMMT Feb 2023
47
62
HMMT Feb 2024
49
61
HMMT Feb 2025
48
63
BRUMO 2025
50
72
MATH-500
71

Frequently Asked Questions

Which is better, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash is ahead overall, 56 to 48. The biggest single separator in this matchup is MMMU-Pro, where the scores are 74 and 42.

Which is better for knowledge tasks, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash has the edge for knowledge tasks in this comparison, averaging 47.3 versus 41.5. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Seed 1.6 Flash or GPT-OSS 120B?

GPT-OSS 120B has the edge for coding in this comparison, averaging 28.1 versus 27.6. Inside this category, HumanEval is the benchmark that creates the most daylight between them.

Which is better for math, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash has the edge for math in this comparison, averaging 67.1 versus 59.5. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash has the edge for reasoning in this comparison, averaging 66.8 versus 55.2. Inside this category, MRCRv2 is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash has the edge for agentic tasks in this comparison, averaging 54.5 versus 44.8. Inside this category, BrowseComp is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 73.1 versus 48.8. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash has the edge for instruction following in this comparison, averaging 81 versus 79. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, Seed 1.6 Flash or GPT-OSS 120B?

Seed 1.6 Flash has the edge for multilingual tasks in this comparison, averaging 72.8 versus 70.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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