Grok 3 vs Grok 4 Fast
Wins 1 of 6 areas
Facts
Wins 5 of 6 areas
Coding · Agents · Reasoning · Long documents · Following instructions
Grok 4 Fast is the stronger all-rounder.Grok 3 is better at facts.
Scores updated · 25 tests both models report · How we compare
Where each one wins
Tests won in each of the six areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- ReasoningHard problems that need careful thinking04Grok 4 Fast4 of 4 tests
- CodingWriting and fixing software02Grok 4 Fast2 of 2 tests
- AgentsCarrying out multi-step tasks on its own01Grok 4 Fast1 of 1 test
- Long documentsFinding answers in very long texts01Grok 4 Fast1 of 1 test
- Following instructionsDoing exactly what it is asked01Grok 4 Fast1 of 1 test
- FactsGetting facts right instead of making them up21Grok 32 of 3 tests
Agents, long documents and following instructions rest on a single test each.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
Grok 4 Fast costs 97% less for the same work.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Grok 4 Fast pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+19points ahead
- Real work tasks from 44 professionsGDPVal+17.4points ahead
- Reasons across sets of long documentsAA-LCR+15.7points ahead
Where Grok 3 pulls ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+6.1points ahead
Every test, side by side
All 25 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingGrok 4 Fast
- Terminal-Bench HardGrok 4 Fast by 7.511.418.9+7.5
- SciCodeGrok 4 Fast by 7.436.844.2+7.4
ReasoningGrok 4 Fast
- GPQA DiamondGrok 4 Fast by 15.469.384.7+15.4
- Humanity's Last ExamGrok 4 Fast by 154.119.1+15
- ARC-AGI-2Grok 4 Fast by 5.305.3+5.3
- CritPtGrok 4 Fast by 2.902.9+2.9
FactsGrok 3
- AA-Omniscience · Non-hallucinationGrok 4 Fast by 1912.731.7+19
- Vectara HHEM hallucination ratelower is betterGrok 3 by 14.45.820.2+14.4
- AA-Omniscience · AccuracyGrok 3 by 6.128.922.8+6.1
Following instructionsGrok 4 Fast
- IFBenchGrok 4 Fast by 3.646.950.5+3.6
Other results13 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- ARC-AGI-1Grok 4 Fast by 435.548.5+43
- BrowseComp-ZHGrok 4 Fast by 34.210.845+34.2
- τ²-Bench Telecom (AA run)Grok 4 Fast by 1748.865.8+17
- AA Agentic IndexGrok 4 Fast by 14.924.639.5+14.9
- vectara_factual_consistencyGrok 3 by 14.494.279.8+14.4
- SimpleQAGrok 4 Fast by 138295+13
- vectara_avg_summary_lengthGrok 4 Fast by 78 rating points95.9173.9+78 rating
- Artificial Analysis Coding IndexGrok 4 Fast by 7.619.827.4+7.6
- vectara_answer_rateGrok 4 Fast by 6.59399.5+6.5
- AA IntelligenceGrok 4 Fast by 5.812.117.9+5.8
- AA-OmniscienceGrok 4 Fast by 3.3-33.2-29.9+3.3
- AIME 2025Grok 3 by 1.393.392+1.3
- LiveCodeBenchtie79.480tie
Questions people ask
Which is better, Grok 3 or Grok 4 Fast?
Grok 4 Fast wins five of the six areas where both have results: coding, agents, reasoning, long documents and following instructions. Grok 3 wins facts.
Which is better for coding?
Grok 4 Fast. It wins 2 of the 2 coding tests both models report; Grok 3 wins none.
Which is cheaper?
Grok 3 costs $4.00 per million input tokens and $20.00 per million output tokens; Grok 4 Fast costs $0.20 and $0.50. That makes Grok 4 Fast about 97% cheaper for the same work.
How do you compare the two?
We use the 25 benchmark tests both models have published scores on. The verdict counts the 12 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 13 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.