xAIUnited States· released Nov 2025

Grok 4.1 Fast

Name: Grok 4.1 Fast
Author: xAI

Provisional: 6 comparable tests so far. Ranked once it reaches 6 across 3 counting categories.

xAI, United States. One of 8 models from this lab on the Index.

Third-party publishedLow confidence (thin coverage)

Snapshot September 8, 2026

OpenCharts Index

41.9

Provisional: not enough comparable tests or counting categories to rank yet · 6 comparable tests · 0 counting categories

Drop any single test and the Index lands between 34.6 and 49.4.

Needs more results (0 of 8 so far)

Distance to today's frontier on the hardest tests. Not a measure of intelligence.

What it's known for

Grok 4.1 Fast, in 6 results.

Its widest gap is on ProofBench, 96.0% behind the best published result. No comparable results yet in knowledge and long context. Between 50% and 60% behind the best published results, on average.

Strongest category

No category counts yet: a category counts once it has more than one comparable test and the model has taken at least half of them. The scores it has are below.

Best single result

Text Arena

Answer the same prompt as a rival model; real users vote blind on which answer they prefer.

1,430

39% expected win rate against the board leader (1,507) · #67 of 92.

Millions of blind votes on real prompts are the market's measure of what people prefer.

Where it trails

ProofBench

Write a complete, rigorous proof, graded for rigor rather than for a final answer.

4.0%

96.0% behind the best published result (100.0%) · #57 of 61.

A proof shows the reasoning itself. A right answer with a wrong argument scores nothing.

Not measured yet

No comparable result yet in these 2 categories. A blank is a blank, never a zero, and it does not lower the Index.

Knowledge
Long context

Covered, but not averaged into the Index:

Reasoning1 of 6 tests · needs 3 · mean 68.4
Coding1 of 7 tests · needs 4 · mean 7.8
Math1 of 5 tests · needs 3 · mean 4.0
Agentic1 of 8 tests · needs 4 · mean 25.6
Multimodalsingle-test category, shown beside the Index · 67.2
Human preferencesingle-test category, shown beside the Index · 78.2

Every score, with its source

See it at work

What Grok 4.1 Fast was asked to do, and how it did.

Every test it has taken, by category, with the kind of task it faced, who produced the number and where the result landed against the best published one. The examples are original and illustrative, never items from the datasets themselves.

Human preference · mean 78.2 across 1 comparable test · a single-test category, shown beside the Index and never averaged into it

Text ArenaLeaderboard

Answer the same prompt as a rival model; real users vote blind on which answer they prefer.

1,430

39% expected win rate against the board leader (1,507)
#67 of 92

reasoning · board 2026-09-02

Source: Arena

Every result is read against the best published one on its test: percent scores as a share of the best above chance, Arena ratings as the expected win rate against the board leader, open-ended values on a log scale. Sitting a harder exam never lowers a model. Every number links to the publisher that produced it.

Head to head

Grok 4.1 Fast against whoever you pick.

Choose a rival. Every counted test both have taken appears side by side as a share of the best published result on that test, with the category means above. A win is a higher share; a gap under 2 points is a tie, because one item on a 45-problem exam is 2.2 points and publishers' own standard errors are of that order.

Grok 4.1 Fast

provisional·Index 41.9D

0 : 4

wins · 0 ties · 4 shared

Grok 4.6

#13·Index 75.2B

Grok 4.6 comes out ahead on 4 of the 4 tests both have taken.

Category means

Reasoning
68.4
82.1
Knowledge
—
65.2
Coding
7.8
80.2
Math
4.0
63.3
Agentic
25.6
90.1
Multimodal
67.2
—
Human preference
78.2
—

Shared tests · biggest gaps first

Vending-Bench 2Agentic
$1,107
$9,047
−67.6
ProofBenchMath
4.0%
51.0%
−47.0
Code Arena (WebDev)Coding
1,240
1,625
−46.3
SimpleBenchReasoning
56.0%
75.9%
−24.3

Bars are distances to the best published result on each test (percent scores above chance, Arena ratings as win rate against the leader, open-ended values on a log scale). Raw values as the publishers report them.

Open Grok 4.6

Scores

Every test, every source

The best published run per benchmark, the raw value as the publisher reports it, who produced the number, how close it comes to the best published result on that test, and where the model sits among every model scored on it. Percent scores are read above chance, Arena ratings as a win rate against the board leader, open-ended values on a log scale. A test with too few models to compare against is shown but not counted.

Category means

Reasoning68.4 · 1/6
Knowledge—
Coding7.8 · 1/7
Math4.0 · 1/5
Agentic25.6 · 1/8
Multimodalbeside67.2 · 1/1
Human preferencebeside78.2 · 1/1
Long context—

Mean · tests taken of the category's comparable tests. A faded category either rests on fewer than half of them or is a single-test category (marked “beside”), which is shown next to the Index and never averaged into it.

SimpleBenchLeaderboardReasoning

56.0%

68.4% of the best (81.9%)
33th percentile of 46

non-reasoning

Source: Epoch AI — AI Benchmarking Hub

Code Arena (WebDev)LeaderboardCoding

1,240

4% expected win rate against the board leader (1,797)
6th percentile of 86

reasoning · board 2026-09-05

Source: Arena (LMArena) — Leaderboard Dataset

ProofBenchLeaderboardMath

4.0%