Grok 4.1 Fast vs Mercury 2

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

Grok 4.1 Fast is clearly ahead on the aggregate, 76 to 65. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Grok 4.1 Fast's sharpest advantage is in multimodal & grounded, where it averages 87.4 against 68.3. The single biggest benchmark swing on the page is MMMU-Pro, 91 to 66.

Mercury 2 is the reasoning model in the pair, while Grok 4.1 Fast 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. Grok 4.1 Fast gives you the larger context window at 1M, compared with 128K for Mercury 2.

Quick Verdict

Pick Grok 4.1 Fast if you want the stronger benchmark profile. Mercury 2 only becomes the better choice if you want the stronger reasoning-first profile.

Agentic

Grok 4.1 Fast

Grok 4.1 Fast

71

Mercury 2

63.7

74
Terminal-Bench 2.0
63
73
BrowseComp
67
66
OSWorld-Verified
62

Coding

Grok 4.1 Fast

Grok 4.1 Fast

59.5

Mercury 2

41.1

86
HumanEval
75
68
SWE-bench Verified
46
54
LiveCodeBench
38
63
SWE-bench Pro
43

Multimodal & Grounded

Grok 4.1 Fast

Grok 4.1 Fast

87.4

Mercury 2

68.3

91
MMMU-Pro
66
83
OfficeQA Pro
71

Reasoning

Grok 4.1 Fast

Grok 4.1 Fast

88.3

Mercury 2

80.1

90
SimpleQA
82
88
MuSR
82
87
BBH
87
87
LongBench v2
77
89
MRCRv2
76

Knowledge

Grok 4.1 Fast

Grok 4.1 Fast

69.2

Mercury 2

57.2

94
MMLU
78
92
GPQA
78
90
SuperGPQA
76
88
OpenBookQA
74
81
MMLU-Pro
72
20
HLE
9
83
FrontierScience
69

Instruction Following

Grok 4.1 Fast

Grok 4.1 Fast

90

Mercury 2

84

90
IFEval
84

Multilingual

Grok 4.1 Fast

Grok 4.1 Fast

84.8

Mercury 2

79.7

88
MGSM
81
83
MMLU-ProX
79

Mathematics

Grok 4.1 Fast

Grok 4.1 Fast

92.3

Mercury 2

80.9

96
AIME 2023
81
98
AIME 2024
83
97
AIME 2025
82
92
HMMT Feb 2023
77
94
HMMT Feb 2024
79
93
HMMT Feb 2025
78
95
BRUMO 2025
80
89
MATH-500
82

Frequently Asked Questions

Which is better, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast is ahead overall, 76 to 65. The biggest single separator in this matchup is MMMU-Pro, where the scores are 91 and 66.

Which is better for knowledge tasks, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for knowledge tasks in this comparison, averaging 69.2 versus 57.2. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for coding in this comparison, averaging 59.5 versus 41.1. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.

Which is better for math, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for math in this comparison, averaging 92.3 versus 80.9. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for reasoning in this comparison, averaging 88.3 versus 80.1. Inside this category, MRCRv2 is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for agentic tasks in this comparison, averaging 71 versus 63.7. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for multimodal and grounded tasks in this comparison, averaging 87.4 versus 68.3. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for instruction following in this comparison, averaging 90 versus 84. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, Grok 4.1 Fast or Mercury 2?

Grok 4.1 Fast has the edge for multilingual tasks in this comparison, averaging 84.8 versus 79.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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