Gemma 4 31B vs Grok 4.20

Gemma 4 31B leads Grok 4.20 on coding, 39.0 to 33.3 on the Vibe Coding Index, and Gemma 4 31B costs 6.3x less per output token ($0.40 vs $2.50 per million). Updated October 21, 2026; 15 benchmarks have a result for both.

Replace Gemma 4 31B Replace Grok 4.20

Gemma 4 31BGoogle

Coding: 39.0
Overall: 42.1
Output $/M: $0.40

Grok 4.20xAI

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

vs boards won of 15 shared, 1 tied

Gemma 4 31B or Grok 4.20: which to pick

Pick Gemma 4 31B for coding: it scores 39.0 on the Vibe Coding Index against 33.3 for Grok 4.20.

Pick Grok 4.20 for a larger context window (2M against 262K tokens) and work measured by Terminal-Bench Hard (Artificial Analysis run) or AA Intelligence Index, where it leads.

Model AGemma 4 31BGoogle39.0/1002 independent benchmarksNo cost per solved task Model BGrok 4.20xAI33.3/1002 independent benchmarks$0.72 per solved task

155640

Shared results: 15
Gemma 4 31B only: 56
Grok 4.20 only: 40
Like-for-like categories: 6 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
Gemma 4 31B
Gemma 4 31B scores 39.0 against 33.3.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
Grok 4.20
Grok 4.20 leads, 25.7 against 14.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Gemma 4 31B has a AA Agentic Index result, 4.2.
Directional only
Reasoning
GPQA Diamond
No call
Only Grok 4.20 has a GPQA Diamond result, 88.6%.
Directional only
Math
AIME
No call
Only Grok 4.20 has a AIME result, 96.5%.
Directional only
Knowledge
MMLU Pro
No call
Only Grok 4.20 has a MMLU Pro result, 86.3%.
Directional only
Web design
Design Arena: websites
No call
Only Grok 4.20 has a Design Arena: websites result, 1229.
Directional only
Long documents
Listed context window
Grok 4.20
Grok 4.20 takes 2M tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemma 4 31B
Gemma 4 31B $0.0003, Grok 4.20 $0.0025 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Grok 4.20 has the number, $0.72.
Directional only

At a glance

Coding index: Gemma 4 31B 39.0 from 2 benchmarks, Grok 4.20 33.3 from 2 benchmarks.
Widest category: Agentic work, 27.5 points apart on average over 1 shared benchmark.
Widest single gap: τ²-Bench Telecom: Gemma 4 31B 65.5% against Grok 4.20 93.0%, 27.5 points apart on a 0 to 100 scale.
Output price: Gemma 4 31B $0.40 against Grok 4.20 $2.50 per million output tokens, 6.3x apart.
Context window: Gemma 4 31B takes 262K 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	Gemma 4 31B	Grok 4.20	Ties
Coding	0	1	1 tie
Intelligence	0	2
Agentic work	0	1
Reasoning	0	3
Knowledge	1	1
General	3	2
All shared boards	4	10	1 tie

CodingLike-for-likeSix of these boards feed the Vibe Coding Index01

Coding benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
LiveBench coding	49.0%	Not measured	Only Gemma 4 31B measured
LMArena WebDev	1367	Not measured	Only Gemma 4 31B measured
AA Coding Index	43.4	Not measured	Only Gemma 4 31B measured
LiveCodeBench (Vals AI)	Not measured	84.3%	Only Grok 4.20 measured
SWE-bench Verified (Vals AI)	Not measured	72.2%	Only Grok 4.20 measured
Vibe Code Bench (Vals AI)	Not measured	4.1%	Only Grok 4.20 measured
Code migration (Vals AI)	Not measured	0.3%	Only Grok 4.20 measured
Terminal-Bench 2.1 (Vals AI)	Not measured	44.2%	Only Grok 4.20 measured
SciCode	45.5%	Not measured	Only Gemma 4 31B measured
Terminal-Bench Hard (Artificial Analysis run)	36.4%	37.9%	Grok 4.20
Terminal-Bench	Not measured	57.3%	Only Grok 4.20 measured
WeirdML	52.3%	52.3%	Tie
ALE-Bench	925.5	Not measured	Only Gemma 4 31B measured
LMArena Text: coding	1459	Not measured	Only Gemma 4 31B measured
LMArena Text: software and IT	1463	Not measured	Only Gemma 4 31B measured
LMArena WebDev: React	1359	Not measured	Only Gemma 4 31B measured
LMArena WebDev: HTML	1380	Not measured	Only Gemma 4 31B measured
SciCode	8.9%	Not measured	Only Gemma 4 31B measured
Neither model has a result on the other 21 boards here

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

Intelligence benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
AA Intelligence Index	14.7	25.7	Grok 4.20
Epoch Capabilities Index	143.0	152.1	Grok 4.20

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

Agentic work benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
AA Agentic Index	4.2	Not measured	Only Gemma 4 31B 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
LiveBench research	44.4%	Not measured	Only Gemma 4 31B measured
LiveBench browser	4.0%	Not measured	Only Gemma 4 31B measured
LiveBench long agentic	13.3%	Not measured	Only Gemma 4 31B measured
Finance Agent (Vals AI)	Not measured	28.5%	Only Grok 4.20 measured
Tax Agent Bench (Vals AI)	Not measured	7.0%	Only Grok 4.20 measured
Legal Research Bench (Vals AI)	Not measured	13.9%	Only Grok 4.20 measured
Excel Modeling Benchmark (Vals AI)	Not measured	11.7%	Only Grok 4.20 measured
τ²-Bench Telecom	65.5%	93.0%	Grok 4.20
Vending-Bench 2	Not measured	$4,663	Only Grok 4.20 measured
Neither model has a result on the other 25 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index03

Reasoning benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
GPQA Diamond	Not measured	88.6%	Only Grok 4.20 measured
LiveBench reasoning	68.3%	Not measured	Only Gemma 4 31B measured
MMMU Pro (Vals AI)	Not measured	83.5%	Only Grok 4.20 measured
GPQA Diamond (Artificial Analysis run)	85.7%	91.1%	Grok 4.20
Humanity's Last Exam (Artificial Analysis run)	23.6%	34.5%	Grok 4.20
GPQA Diamond (Epoch AI run)	75.8%	Not measured	Only Gemma 4 31B 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	1448	Not measured	Only Gemma 4 31B measured
LMArena Text: expert	1464	Not measured	Only Gemma 4 31B measured
LMArena Text: hard prompts in English	1456	Not measured	Only Gemma 4 31B measured
LMArena Vision: diagrams	1283	Not measured	Only Gemma 4 31B measured
LMArena Vision: homework	1310	Not measured	Only Gemma 4 31B measured
Kagi LLM Benchmark	63.5%	75.0%	Grok 4.20
Neither model has a result on the other 8 boards here

MathDirectional onlyPublic boards, shown as published, kept out of the index4 boards, none shared

Math benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
AIME	Not measured	96.5%	Only Grok 4.20 measured
OTIS Mock AIME	73.3%	Not measured	Only Gemma 4 31B measured
LMArena Text: math	1463	Not measured	Only Gemma 4 31B measured
LMArena Text: mathematical work	1465	Not measured	Only Gemma 4 31B measured
Neither model has a result on the other 9 boards here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index11

Knowledge benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
MMLU Pro	Not measured	86.3%	Only Grok 4.20 measured
LegalBench (Vals AI)	Not measured	77.7%	Only Grok 4.20 measured
CaseLaw (Vals AI)	52.6%	54.4%	Grok 4.20
CorpFin (Vals AI)	Not measured	63.7%	Only Grok 4.20 measured
TaxEval (Vals AI)	Not measured	74.1%	Only Grok 4.20 measured
MortgageTax (Vals AI)	61.4%	45.4%	Gemma 4 31B
MedQA (Vals AI)	Not measured	94.5%	Only Grok 4.20 measured
MedCode (Vals AI)	Not measured	32.2%	Only Grok 4.20 measured
SimpleQA Verified	10.4%	Not measured	Only Gemma 4 31B measured
LMArena Text: science	1457	Not measured	Only Gemma 4 31B measured
LMArena Text: medicine and healthcare	1451	Not measured	Only Gemma 4 31B measured
LMArena Text: legal and government	1438	Not measured	Only Gemma 4 31B measured
LMArena Text: business and finance	1430	Not measured	Only Gemma 4 31B measured
FACTS Benchmark Suite	45.3%	Not measured	Only Gemma 4 31B measured
Neither model has a result on the other 4 boards here

Web designDirectional onlyPublic boards, shown as published, kept out of the index9 boards, none shared

Web design benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
Design Arena: websites	Not measured	1229	Only Grok 4.20 measured
Design Arena: UI components	Not measured	1199	Only Grok 4.20 measured
Design Arena: game dev	Not measured	1192	Only Grok 4.20 measured
Design Arena: data viz	Not measured	1217	Only Grok 4.20 measured
Design Arena: 3D	Not measured	1193	Only Grok 4.20 measured
Design Arena: all code categories	Not measured	1221	Only Grok 4.20 measured
Design Arena: SVG	Not measured	1164	Only Grok 4.20 measured
Design Arena: ASCII art	Not measured	1174	Only Grok 4.20 measured
LiveBench design	58.4%	Not measured	Only Gemma 4 31B measured

GeneralLike-for-likePublic boards, shown as published, kept out of the index32

General benchmarks for Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	Grok 4.20	Leader
LiveBench data analysis	53.3%	Not measured	Only Gemma 4 31B measured
SAGE (Vals AI)	55.0%	38.2%	Gemma 4 31B
MedScribe (Vals AI)	Not measured	63.4%	Only Grok 4.20 measured
Vals Multimodal Index	Not measured	39.1%	Only Grok 4.20 measured
IFBench	75.6%	81.2%	Grok 4.20
Long context reasoning (AA-LCR)	69.7%	69.0%	Gemma 4 31B
DTBench	82.7%	90.1%	Grok 4.20
LMCA	39.3%	38.7%	Gemma 4 31B
CL-bench	Not measured	22.2%	Only Grok 4.20 measured
Surface Evolver Bench	30.6%	Not measured	Only Gemma 4 31B measured
CL-bench Life	Not measured	11.9%	Only Grok 4.20 measured
LMArena Text	1443	Not measured	Only Gemma 4 31B measured
LMArena Text: instruction following	1433	Not measured	Only Gemma 4 31B measured
LMArena Text: creative writing	1417	Not measured	Only Gemma 4 31B measured
LMArena Vision	1276	Not measured	Only Gemma 4 31B measured
LMArena Text: English	1451	Not measured	Only Gemma 4 31B measured
LMArena Text: non-English	1430	Not measured	Only Gemma 4 31B measured
LMArena Text: Chinese	1475	Not measured	Only Gemma 4 31B measured
LMArena Text: French	1436	Not measured	Only Gemma 4 31B measured
LMArena Text: Spanish	1442	Not measured	Only Gemma 4 31B measured
LMArena Text: Russian	1460	Not measured	Only Gemma 4 31B measured
LMArena Text: Polish	1433	Not measured	Only Gemma 4 31B measured
LMArena Text: multi-turn	1452	Not measured	Only Gemma 4 31B measured
LMArena Text: longer queries	1446	Not measured	Only Gemma 4 31B measured
LMArena Text: writing and language	1432	Not measured	Only Gemma 4 31B measured
LMArena Text: entertainment and media	1405	Not measured	Only Gemma 4 31B measured
LMArena Vision: English	1271	Not measured	Only Gemma 4 31B measured
LMArena Vision: Chinese	1326	Not measured	Only Gemma 4 31B measured
LMArena Vision: reading text	1282	Not measured	Only Gemma 4 31B measured
LMArena Vision: humor	1280	Not measured	Only Gemma 4 31B measured
LMArena Vision: captioning	1218	Not measured	Only Gemma 4 31B measured
LMArena Vision: recognizing things	1226	Not measured	Only Gemma 4 31B measured
LMArena Vision: creative writing	1285	Not measured	Only Gemma 4 31B measured
LMArena Document	1425	Not measured	Only Gemma 4 31B 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 Gemma 4 31B and Grok 4.20
Benchmark	Gemma 4 31B	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

Gemma 4 31B$0.0003Fits in one request

Grok 4.20$0.0025Fits in one request

Gemma 4 31B costs less

Repository review

50K input + 3K output tokens

Gemma 4 31B$0.0082Fits in one request

Grok 4.20$0.070Fits in one request

Gemma 4 31B costs less

Agent loop

200K input + 10K output tokens

Gemma 4 31B$0.032Fits in one request

Grok 4.20$0.275Fits in one request

Gemma 4 31B 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 Gemma 4 31B and Grok 4.20
Specification	Google Gemma 4 31B	SpaceXAI Grok 4.20
Maker	Google	xAI
Weights	Open weights	No public weights listed
Released	April 2, 2026	March 31, 2026
Context window	262K	2M
Input $/Mtok	$0.14	$1.25
Output $/Mtok	$0.40	$2.50
Coding index	39.0	33.3
Independent measurements behind it	2	2
Cost per solved task	Not computable	$0.72
Source	OpenRouter listing	OpenRouter listing

Questions

Is Gemma 4 31B better than Grok 4.20 for coding?

Pick Gemma 4 31B for coding: it scores 39.0 on the Vibe Coding Index against 33.3 for Grok 4.20. Pick Grok 4.20 for a larger context window (2M against 262K tokens) and work measured by Terminal-Bench Hard (Artificial Analysis run) or AA Intelligence Index, where it leads.

Which is cheaper, Gemma 4 31B or Grok 4.20?

Gemma 4 31B costs $0.14 per million input tokens and $0.40 per million output tokens; Grok 4.20 costs $1.25 and $2.50. Cost per solved task is known for Grok 4.20 only.

Which has the bigger context window, Gemma 4 31B or Grok 4.20?

Grok 4.20, with 2M tokens against 262K.

How many benchmarks is the Gemma 4 31B vs Grok 4.20 comparison based on?

15 benchmarks have a result for both models as of October 21, 2026. Gemma 4 31B's coding index rests on 2 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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<p style="font:13px/1.4 sans-serif;margin:6px 0 0">Source: <a href="https://llmbenchmark.ai/compare/gemma-4-31b-it-vs-grok-4-20">LLMBenchmark.ai, Gemma 4 31B vs Grok 4.20</a></p>

Gemma 4 31B 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