GeekRadar / The comparison desk

COMPARE.

AI models

xai

X-Ai/Grok-4-Fast-Reasoning

AI model Released Dec 18, 2025

Context window: 2,000,000 tokens
Maximum output: 2,000,000 tokens
Open weights: No

Capability & preference

Human preference · Arena

Overall text preferences from head-to-head votes. Not factual accuracy or a task-success rate.

X-Ai/Grok-4-Fast-Reasoning 1399.7 grok-4-fast-reasoning · 95% interval 1394.6–1404.7 · 18,269 votes · 2026-10-15

Recorded results

Only the same benchmark, version, workload, scenario and unit share a row. Missing results are not zero. System results include the full submitted hardware and software configuration.

Arena text preference / chinesehuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,436.63 rating

Confidence interval: 1,419.42 – 1,453.84

1155 votes

Oct 15, 2026

Category: chinese
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / codinghuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,420.32 rating

Confidence interval: 1,410.99 – 1,429.65

3940 votes

Oct 15, 2026

Category: coding
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / creative_writinghuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,377.72 rating

Confidence interval: 1,365.93 – 1,389.51

2489 votes

Oct 15, 2026

Category: creative_writing
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / englishhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,406.56 rating

Confidence interval: 1,399.66 – 1,413.46

8097 votes

Oct 15, 2026

Category: english
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / exclude_tieshuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,380.11 rating

Confidence interval: 1,373.09 – 1,387.12

12874 votes

Oct 15, 2026

Category: exclude_ties
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / experthuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,411.47 rating

Confidence interval: 1,392.50 – 1,430.44

942 votes

Oct 15, 2026

Category: expert
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / frenchhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,431.44 rating

Confidence interval: 1,396.97 – 1,465.92

290 votes

Oct 15, 2026

Category: french
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / germanhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,383.67 rating

Confidence interval: 1,353.45 – 1,413.90

365 votes

Oct 15, 2026

Category: german
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / hard_promptshuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,404.89 rating

Confidence interval: 1,398.49 – 1,411.30

9850 votes

Oct 15, 2026

Category: hard_prompts
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / hard_prompts_englishhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,413.54 rating

Confidence interval: 1,404.58 – 1,422.49

4403 votes

Oct 15, 2026

Category: hard_prompts_english
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_business_and_management_and_financial_operationshuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,394.68 rating

Confidence interval: 1,384.80 – 1,404.57

3570 votes

Oct 15, 2026

Category: industry_business_and_management_and_financial_operations
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_entertainment_and_sports_and_mediahuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,366.75 rating

Confidence interval: 1,356.62 – 1,376.88

3307 votes

Oct 15, 2026

Category: industry_entertainment_and_sports_and_media
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_legal_and_governmenthuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,427.26 rating

Confidence interval: 1,410.21 – 1,444.30

1147 votes

Oct 15, 2026

Category: industry_legal_and_government
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_life_and_physical_and_social_sciencehuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,426.84 rating

Confidence interval: 1,416.14 – 1,437.54

2976 votes

Oct 15, 2026

Category: industry_life_and_physical_and_social_science
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_mathematicalhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,401.18 rating

Confidence interval: 1,382.81 – 1,419.56

976 votes

Oct 15, 2026

Category: industry_mathematical
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_medicine_and_healthcarehuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,415.58 rating

Confidence interval: 1,395.82 – 1,435.33

871 votes

Oct 15, 2026

Category: industry_medicine_and_healthcare
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_software_and_it_serviceshuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,416.76 rating

Confidence interval: 1,409.25 – 1,424.27

6520 votes

Oct 15, 2026

Category: industry_software_and_it_services
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / industry_writing_and_literature_and_languagehuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,380.81 rating

Confidence interval: 1,371.61 – 1,390.01

4157 votes

Oct 15, 2026

Category: industry_writing_and_literature_and_language
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / instruction_followinghuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,382.61 rating

Confidence interval: 1,374.38 – 1,390.85

5330 votes

Oct 15, 2026

Category: instruction_following
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / japanesehuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,352.57 rating

Confidence interval: 1,311.57 – 1,393.56

211 votes

Oct 15, 2026

Category: japanese
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / koreanhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,356.51 rating

Confidence interval: 1,325.63 – 1,387.39

370 votes

Oct 15, 2026

Category: korean
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / longer_queryhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,412.57 rating

Confidence interval: 1,403.73 – 1,421.41

4530 votes

Oct 15, 2026

Category: longer_query
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / mathhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,404.06 rating

Confidence interval: 1,386.29 – 1,421.82

1076 votes

Oct 15, 2026

Category: math
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / multi_turnhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,404.45 rating

Confidence interval: 1,393.54 – 1,415.35

2957 votes

Oct 15, 2026

Category: multi_turn
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / non_englishhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,388.69 rating

Confidence interval: 1,382.41 – 1,394.98

10135 votes

Oct 15, 2026

Category: non_english
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / overallhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,399.68 rating

Confidence interval: 1,394.63 – 1,404.72

18269 votes

Oct 15, 2026

Category: overall
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / polishhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,378.98 rating

Confidence interval: 1,357.38 – 1,400.58

744 votes

Oct 15, 2026

Category: polish
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / russianhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,389.13 rating

Confidence interval: 1,374.09 – 1,404.18

1411 votes

Oct 15, 2026

Category: russian
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Arena text preference / spanishhuman preference · 2026-10-15 · rating

X-Ai/Grok-4-Fast-Reasoning

1,403.95 rating

Confidence interval: 1,379.87 – 1,428.03

598 votes

Oct 15, 2026

Category: spanish
Evaluated configuration: grok-4-fast-reasoning
Evaluation type: human preference

Run it locally

Inference · memory estimate

X-Ai/Grok-4-Fast-Reasoning

Closed weights. No supported local deployment or GPU requirement is published.

API cost

USD / month

Input tokens / monthOutput tokens / month

Standard text-token estimate. Excludes taxes, caching, batch discounts, reasoning and multimodal surcharges. Provider limits and regional availability may differ.

X-Ai/Grok-4-Fast-Reasoning

Provider offer

Capabilities

Context window: 2,000,000 tokens
Maximum output: 2,000,000 tokens
Reasoning: Yes
Tool calling: Yes
Open weights: No
Model license: Proprietary

Input modalities

text
image
audio
video

Output modalities

text