Gemini 3.1 Flash Lite Preview vs Grok 4.20

Grok 4.20 leads Gemini 3.1 Flash Lite Preview on coding, 33.3 to 22.7 on the Vibe Coding Index, and Gemini 3.1 Flash Lite Preview costs 1.7x less per output token ($1.50 vs $2.50 per million). Updated October 21, 2026; 31 benchmarks have a result for both.

Replace Gemini 3.1 Flash Lite Preview Replace Grok 4.20

Gemini 3.1 Flash Lite PreviewGoogle

Coding: 22.7
Overall: 36.6
Output $/M: $1.50

Grok 4.20xAI

Coding: 33.3
Overall: 41.0
Output $/M: $2.50

vs boards won of 31 shared

Gemini 3.1 Flash Lite Preview or Grok 4.20: which to pick

Pick Grok 4.20 for coding: it scores 33.3 on the Vibe Coding Index against 22.7 for Gemini 3.1 Flash Lite Preview, though on 2 benchmarks against 3.

Pick Gemini 3.1 Flash Lite Preview for output tokens 1.7x cheaper ($1.50 vs $2.50 per million) and a lower cost per solved task ($0.18 against $0.72).

Model AGemini 3.1 Flash Lite PreviewGoogle22.7/1003 independent benchmarks$0.18 per solved task Model BGrok 4.20xAI33.3/1002 independent benchmarks$0.72 per solved task

314824

Shared results: 31
Gemini 3.1 Flash Lite Preview only: 48
Grok 4.20 only: 24
Like-for-like categories: 8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

Coding
Vibe Coding Index, six public coding benchmarks
Grok 4.20
Grok 4.20 scores 33.3 against 22.7.
3 and 2 benchmarks behind the scores
Intelligence
AA Intelligence Index
Grok 4.20
Grok 4.20 leads, 25.7 against 15.6.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Gemini 3.1 Flash Lite Preview has a AA Agentic Index result, 1.6.
Directional only
Reasoning
GPQA Diamond
Grok 4.20
Grok 4.20 leads, 88.6% against 81.1%.
Same board, both measured
Math
AIME
Grok 4.20
Grok 4.20 leads, 96.5% against 83.3%.
Same board, both measured
Knowledge
MMLU Pro
Grok 4.20
Grok 4.20 leads, 86.3% against 86.2%.
Same board, both measured
Web design
Design Arena: websites
Grok 4.20
Grok 4.20 leads, 1229 against 1083.
Same board, both measured
Long documents
Listed context window
Grok 4.20
Grok 4.20 takes 2M tokens against 1.05M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 3.1 Flash Lite Preview
Gemini 3.1 Flash Lite Preview $0.0010, Grok 4.20 $0.0025 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Gemini 3.1 Flash Lite Preview
Gemini 3.1 Flash Lite Preview $0.18, Grok 4.20 $0.72.
Published attempt cost and pass rate

At a glance

Coding index: Gemini 3.1 Flash Lite Preview 22.7 from 3 benchmarks, Grok 4.20 33.3 from 2 benchmarks.
Widest category: Web design, 16.0 points apart on average over 8 shared benchmarks.
Widest single gap: MortgageTax (Vals AI): Gemini 3.1 Flash Lite Preview 68.0% against Grok 4.20 45.4%, 22.7 points apart on a 0 to 100 scale.
Output price: Gemini 3.1 Flash Lite Preview $1.50 against Grok 4.20 $2.50 per million output tokens, 1.7x apart.
Context window: Gemini 3.1 Flash Lite Preview takes 1.05M tokens, Grok 4.20 2M.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
Category	Gemini 3.1 Flash Lite Preview	Grok 4.20
Coding	1	4
Intelligence	0	1
Agentic work	1	3
Reasoning	0	2
Math	0	1
Knowledge	4	3
Web design	0	8
General	3	0
All shared boards	9	22

CodingLike-for-likeSix of these boards feed the Vibe Coding Index14

Coding benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
LMArena WebDev	1257	Not measured	Only Gemini 3.1 Flash Lite Preview measured
AA Coding Index	34.7	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LiveCodeBench (Vals AI)	80.1%	84.3%	Grok 4.20
SWE-bench Verified (Vals AI)	62.8%	72.2%	Grok 4.20
Vibe Code Bench (Vals AI)	0.0%	4.1%	Grok 4.20
Code migration (Vals AI)	4.6%	0.3%	Gemini 3.1 Flash Lite Preview
ProgramBench (Vals AI)	0.0%	Not measured	Only Gemini 3.1 Flash Lite Preview measured
Terminal-Bench 2.1 (Vals AI)	34.1%	44.2%	Grok 4.20
Terminal-Bench Hard (Artificial Analysis run)	Not measured	37.9%	Only Grok 4.20 measured
Terminal-Bench	Not measured	57.3%	Only Grok 4.20 measured
WeirdML	Not measured	52.3%	Only Grok 4.20 measured
ALE-Bench	797.7	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: coding	1400	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: software and IT	1413	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena WebDev: React	1245	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena WebDev: HTML	1276	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena WebDev: from an image	1336	Not measured	Only Gemini 3.1 Flash Lite Preview measured
SciCode	4.6%	Not measured	Only Gemini 3.1 Flash Lite Preview measured
Neither model has a result on the other 21 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01

Intelligence benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
AA Intelligence Index	15.6	25.7	Grok 4.20
Epoch Capabilities Index	Not measured	152.1	Only Grok 4.20 measured

Agentic workLike-for-likePublic boards, shown as published, kept out of the index13

Agentic work benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
AA Agentic Index	1.6	Not measured	Only Gemini 3.1 Flash Lite Preview measured
Design Arena: agents building web apps	Not measured	1144	Only Grok 4.20 measured
Design Arena: agents building full-stack apps	Not measured	1054	Only Grok 4.20 measured
Design Arena: agents building mobile apps	Not measured	1090	Only Grok 4.20 measured
Design Arena: agents building Android apps	Not measured	1052	Only Grok 4.20 measured
Design Arena: agents building Godot games	Not measured	1089	Only Grok 4.20 measured
Design Arena: HTML slides	Not measured	1180	Only Grok 4.20 measured
Finance Agent (Vals AI)	30.0%	28.5%	Gemini 3.1 Flash Lite Preview
Tax Agent Bench (Vals AI)	3.1%	7.0%	Grok 4.20
Legal Research Bench (Vals AI)	3.4%	13.9%	Grok 4.20
Excel Modeling Benchmark (Vals AI)	8.6%	11.7%	Grok 4.20
τ²-Bench Telecom	Not measured	93.0%	Only Grok 4.20 measured
Vending-Bench 2	Not measured	$4,663	Only Grok 4.20 measured
Neither model has a result on the other 28 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index02

Reasoning benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
GPQA Diamond	81.1%	88.6%	Grok 4.20
MMMU Pro (Vals AI)	82.5%	83.5%	Grok 4.20
GPQA Diamond (Artificial Analysis run)	Not measured	91.1%	Only Grok 4.20 measured
Humanity's Last Exam (Artificial Analysis run)	Not measured	34.5%	Only Grok 4.20 measured
ARC-AGI	Not measured	89.5%	Only Grok 4.20 measured
ARC-AGI-2	Not measured	65.1%	Only Grok 4.20 measured
LMArena Text: hard prompts	1407	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: expert	1398	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: hard prompts in English	1403	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: diagrams	1242	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: homework	1271	Not measured	Only Gemini 3.1 Flash Lite Preview measured
Kagi LLM Benchmark	Not measured	75.0%	Only Grok 4.20 measured
Neither model has a result on the other 10 boards here

MathLike-for-likePublic boards, shown as published, kept out of the index01

Math benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
AIME	83.3%	96.5%	Grok 4.20
LMArena Text: math	1428	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: mathematical work	1417	Not measured	Only Gemini 3.1 Flash Lite Preview measured
Neither model has a result on the other 10 boards here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index43

Knowledge benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
MMLU Pro	86.2%	86.3%	Grok 4.20
LegalBench (Vals AI)	83.8%	77.7%	Gemini 3.1 Flash Lite Preview
CaseLaw (Vals AI)	55.0%	54.4%	Gemini 3.1 Flash Lite Preview
CorpFin (Vals AI)	59.4%	63.7%	Grok 4.20
TaxEval (Vals AI)	71.8%	74.1%	Grok 4.20
MortgageTax (Vals AI)	68.0%	45.4%	Gemini 3.1 Flash Lite Preview
MedQA (Vals AI)	Not measured	94.5%	Only Grok 4.20 measured
MedCode (Vals AI)	47.6%	32.2%	Gemini 3.1 Flash Lite Preview
LMArena Text: science	1425	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: medicine and healthcare	1428	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: legal and government	1418	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: business and finance	1389	Not measured	Only Gemini 3.1 Flash Lite Preview measured
FACTS Benchmark Suite	51.4%	Not measured	Only Gemini 3.1 Flash Lite Preview measured
Neither model has a result on the other 5 boards here

Web designLike-for-likePublic boards, shown as published, kept out of the index08

Web design benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
Design Arena: websites	1083	1229	Grok 4.20
Design Arena: UI components	1072	1199	Grok 4.20
Design Arena: game dev	1029	1192	Grok 4.20
Design Arena: data viz	1045	1217	Grok 4.20
Design Arena: 3D	1048	1193	Grok 4.20
Design Arena: all code categories	1072	1221	Grok 4.20
Design Arena: SVG	1052	1164	Grok 4.20
Design Arena: ASCII art	1167	1174	Grok 4.20
Neither model has a result on the other 1 board here

GeneralLike-for-likePublic boards, shown as published, kept out of the index30

General benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
SAGE (Vals AI)	49.5%	38.2%	Gemini 3.1 Flash Lite Preview
MedScribe (Vals AI)	63.9%	63.4%	Gemini 3.1 Flash Lite Preview
Vals Multimodal Index	41.4%	39.1%	Gemini 3.1 Flash Lite Preview
IFBench	Not measured	81.2%	Only Grok 4.20 measured
Long context reasoning (AA-LCR)	Not measured	69.0%	Only Grok 4.20 measured
DTBench	Not measured	90.1%	Only Grok 4.20 measured
LMCA	Not measured	38.7%	Only Grok 4.20 measured
CL-bench	Not measured	22.2%	Only Grok 4.20 measured
CL-bench Life	Not measured	11.9%	Only Grok 4.20 measured
LMArena Text	1416	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: instruction following	1377	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: creative writing	1401	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision	1240	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: English	1414	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: non-English	1410	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: Chinese	1460	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: German	1430	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: Japanese	1413	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: Korean	1392	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: French	1424	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: Spanish	1421	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: Russian	1420	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: Polish	1443	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: multi-turn	1417	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: longer queries	1394	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: writing and language	1408	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Text: entertainment and media	1386	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: English	1232	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: Chinese	1278	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: reading text	1246	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: humor	1266	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: captioning	1259	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: recognizing things	1308	Not measured	Only Gemini 3.1 Flash Lite Preview measured
LMArena Vision: creative writing	1248	Not measured	Only Gemini 3.1 Flash Lite Preview measured
Neither model has a result on the other 12 boards here

Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared

Image generation benchmarks for Gemini 3.1 Flash Lite Preview and Grok 4.20
Benchmark	Gemini 3.1 Flash Lite Preview	Grok 4.20	Leader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Gemini 3.1 Flash Lite Preview$0.0010Fits in one request

Grok 4.20$0.0025Fits in one request

Gemini 3.1 Flash Lite Preview costs less

Repository review

50K input + 3K output tokens

Gemini 3.1 Flash Lite Preview$0.017Fits in one request

Grok 4.20$0.070Fits in one request

Gemini 3.1 Flash Lite Preview costs less

Agent loop

200K input + 10K output tokens

Gemini 3.1 Flash Lite Preview$0.065Fits in one request

Grok 4.20$0.275Fits in one request

Gemini 3.1 Flash Lite Preview costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Gemini 3.1 Flash Lite Preview and Grok 4.20
Specification	Google Gemini 3.1 Flash Lite Preview	SpaceXAI Grok 4.20
Maker	Google	xAI
Weights	No public weights listed	No public weights listed
Released	March 3, 2026	March 31, 2026
Context window	1.05M	2M
Input $/Mtok	$0.25	$1.25
Output $/Mtok	$1.50	$2.50
Coding index	22.7	33.3
Independent measurements behind it	3	2
Cost per solved task	$0.18	$0.72
Source	OpenRouter listing	OpenRouter listing

Questions

Is Gemini 3.1 Flash Lite Preview better than Grok 4.20 for coding?

Pick Grok 4.20 for coding: it scores 33.3 on the Vibe Coding Index against 22.7 for Gemini 3.1 Flash Lite Preview, though on 2 benchmarks against 3. Pick Gemini 3.1 Flash Lite Preview for output tokens 1.7x cheaper ($1.50 vs $2.50 per million) and a lower cost per solved task ($0.18 against $0.72).

Which is cheaper, Gemini 3.1 Flash Lite Preview or Grok 4.20?

Gemini 3.1 Flash Lite Preview costs $0.25 per million input tokens and $1.50 per million output tokens; Grok 4.20 costs $1.25 and $2.50. Per solved SWE-bench Verified task, Gemini 3.1 Flash Lite Preview costs $0.18 and Grok 4.20 $0.72.

Which has the bigger context window, Gemini 3.1 Flash Lite Preview or Grok 4.20?

Grok 4.20, with 2M tokens against 1.05M.

How many benchmarks is the Gemini 3.1 Flash Lite Preview vs Grok 4.20 comparison based on?

31 benchmarks have a result for both models as of October 21, 2026. Gemini 3.1 Flash Lite Preview's coding index rests on 3 independent benchmarks and Grok 4.20's on 2. Where only one model has a result, the page says so instead of naming a winner.

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<iframe src="https://llmbenchmark.ai/embed/compare/gemini-3-1-flash-lite-preview-vs-grok-4-20" title="Gemini 3.1 Flash Lite Preview vs Grok 4.20, LLMBenchmark.ai" width="100%" height="360" style="border:0;max-width:100%" loading="lazy"></iframe>
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Gemini 3.1 Flash Lite Preview or Grok 4.20: which to pick

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

Math

Knowledge

Web design

Long documents

Everyday cost

Cost per solved task

At a glance

Benchmark by benchmark

What each workload costs

Chat turn

Repository review

Agent loop

Specification differences

Questions

Compare next