Gemini 3.5 Flash vs Grok 4.3
Gemini 3.5 Flash 
Grok 4.3 Verdict
- Gemini 3.5 Flash (medium) leads on quality: 64.1 vs 60.7.
- Gemini 3.5 Flash (medium) is stronger in agents & tools, coding, composite, human preference, knowledge, multimodal, reasoning.
- Grok 4.3 (medium) is stronger in instruction following, long context.
- Grok 4.3 (medium) is 2.2× cheaper ($1.56 vs $3.38 per 1M blended).
- Gemini 3.5 Flash (medium) streams 1.9× faster (217 vs 112 tokens per second).
| Metric | Gemini 3.5 Flash (medium) | Grok 4.3 (medium) |
|---|---|---|
| BenchLeader Index | 64.1 | 60.7 |
| Agents & tools score | 68.0 | 60.1 |
| Coding score | 58.9 | – |
| Composite score | 71.5 | 60.3 |
| Human preference score | 67.8 | – |
| Instruction following score | 72.5 | 80.0 |
| Knowledge score | 74.0 | 72.1 |
| Long context score | 63.6 | 64.0 |
| Multimodal score | 67.6 | 60.2 |
| Reasoning score | 67.1 | – |
| Blended price $/M | $3.38 | $1.56 |
| Output speed | 217 tok/s | 112 tok/s |
| Time to first answer | 15.5 s | 12.1 s |
| Context window | 1M | 1M |
| LMArena Text | 1476 | – |
| LMArena Hard Prompts | 1493 | – |
| LMArena Coding | 1503 | – |
| LMArena WebDev | 1491 | – |
| LMArena Vision | 1306 | – |
| AA Intelligence Index | 33.6 | 24.8 |
| IFBench | 74.6% | 83.3% |
| AA-LCR | 74.3% | 75.0% |
| MMMU-Pro | 83.9% | 75.8% |
| AA-Omniscience | 20.8 | 16.7 |
| Terminal-Bench Hard | 39.4% | 30.3% |
| GPQA Diamond (AA) | 92.1% | 89.0% |
| Humanity's Last Exam (AA) | 41.3% | 30.0% |
| τ²-Bench Telecom (AA) | 95.6% | 91.2% |
Data as of 2026-09-10. Best configuration of each model; every score links to its source on the model pages.
Gemini 3.5 Flash vs Grok 4.3: questions
- Is Gemini 3.5 Flash better than Grok 4.3?
- Gemini 3.5 Flash (medium) leads on quality: 64.1 vs 60.7. The BenchLeader Index combines every independent quality benchmark; Gemini 3.5 Flash (medium) is ahead overall as of 2026-09-10, but check the category scores for your use.
- Is Gemini 3.5 Flash better than Grok 4.3 for agentic tasks?
- Gemini 3.5 Flash scores higher in agentic tasks (68 vs 60 on the category index, where 50 is average).
- Which is cheaper, Gemini 3.5 Flash or Grok 4.3?
- Grok 4.3 is cheaper: $1.56 against $3.38 per million tokens, blended at three input tokens per output token.
- Which is faster, Gemini 3.5 Flash or Grok 4.3?
- Gemini 3.5 Flash streams faster: 217 against 112 output tokens per second.
- Which has the larger context window?
- Both accept 1M tokens of context.