Google: Gemini 3.5 Flash vs SpaceXAI: Grok 4.20
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-11-07.
| Google: Gemini 3.5 Flash | SpaceXAI: Grok 4.20 | |
|---|---|---|
| Vendor | x-ai | |
| Quality Score | 100 | 100 |
| Benchmark Score | 84.2 | 56.5 |
| Input Price | $1.50/M | $1.25/M |
| Output Price | $9.00/M | $2.50/M |
| Context Window | 1,048,576 | 2,000,000 |
| Max Output | 65,536 | 1,800,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | ✓ | - |
| Benchmark Scores | ||
| ai_index | 82.8 | 61.0 |
| ai_index_agentic | 61.8 | - |
| ai_index_coding | 100.0 | - |
| eqbench | - | 45.7 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, Grok 4.20 costs $1.88 and Gemini 3.5 Flash costs $3.75, so Grok 4.20 is about 2.0 times cheaper for the same work.
Grok 4.20 reads up to 2,000,000 tokens at once, roughly 3,000 pages of text, against about 1,573 pages for Gemini 3.5 Flash.
Only Gemini 3.5 Flash offers audio input and video input.
On our blended benchmark score Gemini 3.5 Flash leads 84.2 to 56.5.
Across the 20 tasks where they differ, Gemini 3.5 Flash scores higher on 19 (SQL Generation, Code Review, Code Refactoring and others), Grok 4.20 on 1 (Code Completion).
Gemini 3.5 Flash was released in May 2026 and Grok 4.20 in March 2026.
Pick Gemini 3.5 Flash if you need audio input, video input, benchmark performance or the stronger all-round task scores; pick Grok 4.20 if you need lower cost or long documents.
Costs use current list prices per million tokens; page counts assume about 0.75 words per token and 500 words per page.
Who wins by task?
| Task | Google: Gemini 3.5 Flash | SpaceXAI: Grok 4.20 |
|---|---|---|
| SQL Generation | 168 | 144 |
| Code Review | 164 | 149 |
| Code Completion | 119 | 121 |
| Code Refactoring | 162 | 151 |
| Bug Fixing | 176 | 153 |
| Unit Test Generation | 152 | 134 |
| Code Documentation | 141 | 140 |
| Regex Writing | 133 | 127 |
| CI/CD Pipelines | 143 | 130 |
| Frontend Component Design | 145 | 131 |
| Data Analysis | 167 | 135 |
| CSV / Spreadsheet Cleanup | 153 | 138 |
| ETL Scripting | 152 | 141 |
| JSON Extraction | 138 | 123 |
| Bulk Data Labeling | 124 | 120 |
| OCR / Document Parsing | 146 | 135 |
| Table Extraction from PDFs | 146 | 135 |
| Long-Document Summarization | 157 | 153 |
| Short-Form Summarization | 121 | 119 |
| Blog Post Writing | 138 | 132 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →