Gemini 3.1 Pro Preview Custom Tools vs Grok 4.3
Grok 4.3 costs 4.8x less per output token than Gemini 3.1 Pro Preview Custom Tools ($2.50 vs $12.00 per million). Updated October 21, 2026; 1 benchmarks have a result for both.
Gemini 3.1 Pro Preview Custom Tools or Grok 4.3: which to pick
Only Grok 4.3 has a coding score, 37.4 on the Vibe Coding Index; Gemini 3.1 Pro Preview Custom Tools has none, so the two cannot be ranked on coding.
Pick Gemini 3.1 Pro Preview Custom Tools for a larger context window (1.05M against 1M tokens) and work measured by Vending-Bench 2, where it leads.
- Shared results
- 1
- Gemini 3.1 Pro Preview Custom Tools only
- 0
- Grok 4.3 only
- 103
- Like-for-like categories
- 1 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
No call
Only Grok 4.3 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
No call
Only Grok 4.3 has a AA Intelligence Index result, 24.9.
Directional only
Agentic work
AA Agentic Index
No call
Only Grok 4.3 has a AA Agentic Index result, 15.5.
Directional only
Reasoning
GPQA Diamond
No call
Only Grok 4.3 has a GPQA Diamond result, 91.4%.
Directional only
Knowledge
MMLU Pro
No call
Only Grok 4.3 has a MMLU Pro result, 85.8%.
Directional only
Web design
Design Arena: websites
No call
Only Grok 4.3 has a Design Arena: websites result, 1196.
Directional only
Long documents
Listed context window
Gemini 3.1 Pro Preview Custom Tools
Gemini 3.1 Pro Preview Custom Tools takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Grok 4.3
Gemini 3.1 Pro Preview Custom Tools $0.0080, Grok 4.3 $0.0025 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Grok 4.3 has the number, $0.31.
Directional only
At a glance
- Coding index
- Gemini 3.1 Pro Preview Custom Tools not benchmarked, Grok 4.3 37.4 from 3 benchmarks.
- Widest category
- Agentic work, 23.4 points apart on average over 1 shared benchmark.
- Widest single gap
- Vending-Bench 2: Gemini 3.1 Pro Preview Custom Tools $3,774 against Grok 4.3 $35, 23.4 points apart on a 0 to 100 scale.
- Output price
- Gemini 3.1 Pro Preview Custom Tools $12.00 against Grok 4.3 $2.50 per million output tokens, 4.8x apart.
- Context window
- Gemini 3.1 Pro Preview Custom Tools takes 1.05M tokens, Grok 4.3 1M.
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.
| Category | Gemini 3.1 Pro Preview Custom Tools | Bars | Grok 4.3 | Ties |
|---|---|---|---|---|
| Agentic work | 1 | 0 | ||
| All shared boards | 1 | 0 |
CodingDirectional onlySix of these boards feed the Vibe Coding Index18 boards, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| LMArena WebDev | Not measured | 1358 | Only Grok 4.3 measured |
| AA Coding Index | Not measured | 42.2 | Only Grok 4.3 measured |
| LiveCodeBench (Vals AI) | Not measured | 84.5% | Only Grok 4.3 measured |
| SWE-bench Verified (Vals AI) | Not measured | 71.4% | Only Grok 4.3 measured |
| Vibe Code Bench (Vals AI) | Not measured | 19.4% | Only Grok 4.3 measured |
| Code migration (Vals AI) | Not measured | 6.8% | Only Grok 4.3 measured |
| ProgramBench (Vals AI) | Not measured | 0.0% | Only Grok 4.3 measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 42.0% | Only Grok 4.3 measured |
| SkillsBench (Vals AI) | Not measured | 40.6% | Only Grok 4.3 measured |
| SciCode | Not measured | 48.3% | Only Grok 4.3 measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 37.9% | Only Grok 4.3 measured |
| WeirdML | Not measured | 49.9% | Only Grok 4.3 measured |
| ALE-Bench | Not measured | 944.2 | Only Grok 4.3 measured |
| LMArena Text: coding | Not measured | 1415 | Only Grok 4.3 measured |
| LMArena Text: software and IT | Not measured | 1416 | Only Grok 4.3 measured |
| LMArena WebDev: React | Not measured | 1353 | Only Grok 4.3 measured |
| LMArena WebDev: HTML | Not measured | 1367 | Only Grok 4.3 measured |
| LMArena WebDev: from an image | Not measured | 1375 | Only Grok 4.3 measured |
| Neither model has a result on the other 21 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| AA Intelligence Index | Not measured | 24.9 | Only Grok 4.3 measured |
| Neither model has a result on the other 1 board here | |||
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 15.5 | Only Grok 4.3 measured |
| Design Arena: agents building web apps | Not measured | 1126 | Only Grok 4.3 measured |
| Design Arena: agents building full-stack apps | Not measured | 1006 | Only Grok 4.3 measured |
| Design Arena: agents building mobile apps | Not measured | 1059 | Only Grok 4.3 measured |
| Design Arena: agents building Android apps | Not measured | 961 | Only Grok 4.3 measured |
| Design Arena: agents building Godot games | Not measured | 914 | Only Grok 4.3 measured |
| Design Arena: agents building games | Not measured | 1007 | Only Grok 4.3 measured |
| Design Arena: HTML slides | Not measured | 1008 | Only Grok 4.3 measured |
| Design Arena: PowerPoint slides | Not measured | 1013 | Only Grok 4.3 measured |
| Finance Agent (Vals AI) | Not measured | 37.7% | Only Grok 4.3 measured |
| Tax Agent Bench (Vals AI) | Not measured | 6.2% | Only Grok 4.3 measured |
| Legal Research Bench (Vals AI) | Not measured | 15.4% | Only Grok 4.3 measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 18.4% | Only Grok 4.3 measured |
| τ²-Bench Telecom | Not measured | 97.7% | Only Grok 4.3 measured |
| Vending-Bench 2 | $3,774 | $35 | Gemini 3.1 Pro Preview Custom Tools |
| LMArena Search | Not measured | 1166 | Only Grok 4.3 measured |
| Neither model has a result on the other 25 boards here | |||
ReasoningDirectional onlyPublic boards, shown as published, kept out of the index11 boards, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 91.4% | Only Grok 4.3 measured |
| MMMU Pro (Vals AI) | Not measured | 83.1% | Only Grok 4.3 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 90.1% | Only Grok 4.3 measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 37.2% | Only Grok 4.3 measured |
| GPQA Diamond (Epoch AI run) | Not measured | 88.8% | Only Grok 4.3 measured |
| Chess puzzles | Not measured | 18.0% | Only Grok 4.3 measured |
| LMArena Text: hard prompts | Not measured | 1396 | Only Grok 4.3 measured |
| LMArena Text: expert | Not measured | 1384 | Only Grok 4.3 measured |
| LMArena Text: hard prompts in English | Not measured | 1402 | Only Grok 4.3 measured |
| LMArena Vision: diagrams | Not measured | 1241 | Only Grok 4.3 measured |
| LMArena Vision: homework | Not measured | 1241 | Only Grok 4.3 measured |
| Neither model has a result on the other 11 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| OTIS Mock AIME | Not measured | 93.3% | Only Grok 4.3 measured |
| FrontierMath, tiers 1 to 3 | Not measured | 42.8% | Only Grok 4.3 measured |
| FrontierMath, tier 4 | Not measured | 14.6% | Only Grok 4.3 measured |
| ProofBench | Not measured | 11.0% | Only Grok 4.3 measured |
| LMArena Text: math | Not measured | 1387 | Only Grok 4.3 measured |
| LMArena Text: mathematical work | Not measured | 1396 | Only Grok 4.3 measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 85.8% | Only Grok 4.3 measured |
| LegalBench (Vals AI) | Not measured | 84.5% | Only Grok 4.3 measured |
| CaseLaw (Vals AI) | Not measured | 79.3% | Only Grok 4.3 measured |
| CorpFin (Vals AI) | Not measured | 68.5% | Only Grok 4.3 measured |
| TaxEval (Vals AI) | Not measured | 70.8% | Only Grok 4.3 measured |
| MortgageTax (Vals AI) | Not measured | 48.3% | Only Grok 4.3 measured |
| MedCode (Vals AI) | Not measured | 38.1% | Only Grok 4.3 measured |
| SimpleQA Verified | Not measured | 33.2% | Only Grok 4.3 measured |
| LMArena Text: science | Not measured | 1399 | Only Grok 4.3 measured |
| LMArena Text: medicine and healthcare | Not measured | 1384 | Only Grok 4.3 measured |
| LMArena Text: legal and government | Not measured | 1386 | Only Grok 4.3 measured |
| LMArena Text: business and finance | Not measured | 1381 | Only Grok 4.3 measured |
| Neither model has a result on the other 6 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| Design Arena: websites | Not measured | 1196 | Only Grok 4.3 measured |
| Design Arena: UI components | Not measured | 1192 | Only Grok 4.3 measured |
| Design Arena: game dev | Not measured | 1174 | Only Grok 4.3 measured |
| Design Arena: data viz | Not measured | 1179 | Only Grok 4.3 measured |
| Design Arena: 3D | Not measured | 1125 | Only Grok 4.3 measured |
| Design Arena: all code categories | Not measured | 1187 | Only Grok 4.3 measured |
| Design Arena: SVG | Not measured | 1081 | Only Grok 4.3 measured |
| Design Arena: ASCII art | Not measured | 1125 | Only Grok 4.3 measured |
| Neither model has a result on the other 1 board here | |||
GeneralDirectional onlyPublic boards, shown as published, kept out of the index32 boards, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | Leader |
|---|---|---|---|
| Public Benefits Bench (Vals AI) | Not measured | 51.7% | Only Grok 4.3 measured |
| SAGE (Vals AI) | Not measured | 19.7% | Only Grok 4.3 measured |
| MedScribe (Vals AI) | Not measured | 74.4% | Only Grok 4.3 measured |
| Vals Multimodal Index | Not measured | 43.3% | Only Grok 4.3 measured |
| IFBench | Not measured | 83.3% | Only Grok 4.3 measured |
| Long context reasoning (AA-LCR) | Not measured | 75.0% | Only Grok 4.3 measured |
| DTBench | Not measured | 90.7% | Only Grok 4.3 measured |
| LMCA | Not measured | 38.3% | Only Grok 4.3 measured |
| LMArena Text | Not measured | 1397 | Only Grok 4.3 measured |
| LMArena Text: instruction following | Not measured | 1366 | Only Grok 4.3 measured |
| LMArena Text: creative writing | Not measured | 1380 | Only Grok 4.3 measured |
| LMArena Vision | Not measured | 1229 | Only Grok 4.3 measured |
| LMArena Text: English | Not measured | 1404 | Only Grok 4.3 measured |
| LMArena Text: non-English | Not measured | 1385 | Only Grok 4.3 measured |
| LMArena Text: Chinese | Not measured | 1422 | Only Grok 4.3 measured |
| LMArena Text: German | Not measured | 1395 | Only Grok 4.3 measured |
| LMArena Text: Japanese | Not measured | 1379 | Only Grok 4.3 measured |
| LMArena Text: Korean | Not measured | 1354 | Only Grok 4.3 measured |
| LMArena Text: French | Not measured | 1411 | Only Grok 4.3 measured |
| LMArena Text: Spanish | Not measured | 1399 | Only Grok 4.3 measured |
| LMArena Text: Russian | Not measured | 1399 | Only Grok 4.3 measured |
| LMArena Text: Polish | Not measured | 1398 | Only Grok 4.3 measured |
| LMArena Text: multi-turn | Not measured | 1406 | Only Grok 4.3 measured |
| LMArena Text: longer queries | Not measured | 1393 | Only Grok 4.3 measured |
| LMArena Text: writing and language | Not measured | 1385 | Only Grok 4.3 measured |
| LMArena Text: entertainment and media | Not measured | 1370 | Only Grok 4.3 measured |
| LMArena Vision: English | Not measured | 1235 | Only Grok 4.3 measured |
| LMArena Vision: Chinese | Not measured | 1257 | Only Grok 4.3 measured |
| LMArena Vision: reading text | Not measured | 1235 | Only Grok 4.3 measured |
| LMArena Vision: humor | Not measured | 1222 | Only Grok 4.3 measured |
| LMArena Vision: recognizing things | Not measured | 1217 | Only Grok 4.3 measured |
| LMArena Vision: creative writing | Not measured | 1237 | Only Grok 4.3 measured |
| Neither model has a result on the other 14 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Gemini 3.1 Pro Preview Custom Tools | Grok 4.3 | 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
Grok 4.3 costs less
Repository review
50K input + 3K output tokens
Grok 4.3 costs less
Agent loop
200K input + 10K output tokens
Grok 4.3 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.
| Specification | Google Gemini 3.1 Pro Preview Custom Tools | SpaceXAI Grok 4.3 |
|---|---|---|
| Maker | xAI | |
| Weights | No public weights listed | No public weights listed |
| Released | February 25, 2026 | April 30, 2026 |
| Context window | 1.05M | 1M |
| Input $/Mtok | $2.00 | $1.25 |
| Output $/Mtok | $12.00 | $2.50 |
| Coding index | Not benchmarked | 37.4 |
| Independent measurements behind it | 0 | 3 |
| Cost per solved task | Not computable | $0.31 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Gemini 3.1 Pro Preview Custom Tools better than Grok 4.3 for coding?
Only Grok 4.3 has a coding score, 37.4 on the Vibe Coding Index; Gemini 3.1 Pro Preview Custom Tools has none, so the two cannot be ranked on coding. Pick Gemini 3.1 Pro Preview Custom Tools for a larger context window (1.05M against 1M tokens) and work measured by Vending-Bench 2, where it leads.
Which is cheaper, Gemini 3.1 Pro Preview Custom Tools or Grok 4.3?
Gemini 3.1 Pro Preview Custom Tools costs $2.00 per million input tokens and $12.00 per million output tokens; Grok 4.3 costs $1.25 and $2.50. Cost per solved task is known for Grok 4.3 only.
Which has the bigger context window, Gemini 3.1 Pro Preview Custom Tools or Grok 4.3?
Gemini 3.1 Pro Preview Custom Tools, with 1.05M tokens against 1M.
How many benchmarks is the Gemini 3.1 Pro Preview Custom Tools vs Grok 4.3 comparison based on?
1 benchmarks have a result for both models as of October 21, 2026. Gemini 3.1 Pro Preview Custom Tools's coding index rests on 0 independent benchmarks and Grok 4.3's on 3. Where only one model has a result, the page says so instead of naming a winner.