Grok 4.1 Fast vs Kimi K2.5
Wins 0 of 8 areas
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Wins 8 of 8 areas
Coding · Agents · Reasoning · Facts · Images and charts · Math · Long documents · Following instructions
Kimi K2.5 is the stronger all-rounder.Grok 4.1 Fast is cheaper.
Scores updated · 26 tests both models report · How we compare
Where each one wins
Tests won in each of the eight areas we test. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- CodingWriting and fixing software03Kimi K2.53 of 3 tests
- FactsGetting facts right instead of making them up03Kimi K2.53 of 3 tests
- ReasoningHard problems that need careful thinking02Kimi K2.52 of 3 tests · 1 tie
- Images and chartsUnderstanding pictures, charts and video02Kimi K2.52 of 2 tests
- MathCompetition and research-level math01Kimi K2.51 of 2 tests · 1 tie
- AgentsCarrying out multi-step tasks on its own01Kimi K2.51 of 1 test
- Long documentsFinding answers in very long texts01Kimi K2.51 of 1 test
- Following instructionsDoing exactly what it is asked01Kimi K2.51 of 1 test
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 4.1 Fast costs 81% 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 Kimi K2.5 pulls ahead
- Follows unfamiliar, precisely checkable instructionsIFBench+17.5points ahead
- Harder college exam questions with imagesMMMU-Pro+12.1points ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+11.4points ahead
Where Grok 4.1 Fast pulls ahead
No clear win on a test scored out of 100.
Every test, side by side
All 26 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingKimi K2.5
- LMArena · WebDevKimi K2.5 by 196 rating points12401436+196 rating
- Terminal-Bench HardKimi K2.5 by 10.624.234.8+10.6
- SciCodeKimi K2.5 by 4.844.249+4.8
ReasoningKimi K2.5
- Humanity's Last ExamKimi K2.5 by 11.419.330.7+11.4
- GPQA DiamondKimi K2.5 by 2.685.387.9+2.6
- CritPttie2.93.1tie
FactsKimi K2.5
- AA-Omniscience · AccuracyKimi K2.5 by 10.125.135.2+10.1
- AA-Omniscience · Non-hallucinationKimi K2.5 by 7.726.634.3+7.7
- Vectara HHEM hallucination ratelower is betterKimi K2.5 by 519.214.2+5
Images and chartsKimi K2.5
- MMMU-ProKimi K2.5 by 12.163.375.4+12.1
- LMArena · VisionKimi K2.5 by 68 rating points12011269+68 rating
Following instructionsKimi K2.5
- IFBenchKimi K2.5 by 17.552.770.2+17.5
Other results10 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.
- Artificial Analysis Coding IndexKimi K2.5 by 27.319.546.8+27.3
- AA-OmniscienceKimi K2.5 by 22.6-29.9-7.3+22.6
- matharena_visual_math_overallKimi K2.5 by 11.66980.6+11.6
- AA Agentic IndexGrok 4.1 Fast by 11.232.921.7+11.2
- vectara_answer_rateGrok 4.1 Fast by 7.599.792.2+7.5
- vectara_factual_consistencyKimi K2.5 by 580.885.8+5
- HMMT Nov. 2025Grok 4.1 Fast by 4.193.389.2+4.1
- AA IntelligenceKimi K2.5 by 3.120.423.5+3.1
- τ²-Bench Telecom (AA run)Kimi K2.5 by 2.693.395.9+2.6
- vectara_avg_summary_lengthKimi K2.5 by 12.5 rating points99.5112+12.5 rating
Questions people ask
Which is better, Grok 4.1 Fast or Kimi K2.5?
Kimi K2.5 wins all eight areas we test: coding, agents, reasoning, facts, images and charts, math, long documents and following instructions. Grok 4.1 Fast wins none, but costs 81% less.
Which is better for coding?
Kimi K2.5. It wins 3 of the 3 coding tests both models report; Grok 4.1 Fast wins none.
Which is cheaper?
Grok 4.1 Fast costs $0.20 per million input tokens and $0.50 per million output tokens; Kimi K2.5 costs $0.60 and $3.00. That makes Grok 4.1 Fast about 81% cheaper for the same work.
How do you compare the two?
We use the 26 benchmark tests both models have published scores on. The verdict counts the 16 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 10 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.