Grok 4.20 (Reasoning) vs Gemini 3.1 Pro Preview
Side-by-side comparison across metrics, pricing, and overall score — every value traced to a source.
Verdict: Gemini 3.1 Pro Preview ranks highest overall (#5) with a score of 50.8.
The best choice still depends on which metrics matter for your workload — per-metric winners are marked below.
What the numbers hide
Computed from the published values below — no estimates, no generated claims.
Fragile verdict
The overall winner flips to Gemini 3.1 Pro Preview if Context Window is weighted at 25% (it counts for 18% today). If context window drives your decision, the ranking above may not be your ranking.
Fragile verdict
The overall winner flips to Gemini 3.1 Pro Preview if Output Price is weighted at 10% (it counts for 18% today). If output price drives your decision, the ranking above may not be your ranking.
Real tradeoff
Grok 4.20 (Reasoning) clearly beats Gemini 3.1 Pro Preview on Input Price but clearly loses on Context Window — this pair is a priorities question, not a quality question.
What nobody reports
SWE-Bench Pro Score (1 of 2 missing) — the questions worth asking vendors directly.
AI hot take
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| Metric | Grok 4.20 (Reasoning)xAI | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|
| Overall OptiSift Score | 31.6#12 | 50.8#5 |
| Input Price | $1.25 | $2 |
| Output Price | $2.5 | $12 |
| Cache Read Price | $0.2 | $0.2 |
| Context Window | 1M | 1.0M |
| Max Output Tokens | 30K | 66K |
| SWE-Bench Pro Score | — | 54.2% |
| Tool Calling | Yes | Yes |
| Extended Reasoning | Yes | Yes |
About these models
#12Grok 4.20 (Reasoning)
xAI
Grok 4.20 (Reasoning) is xAI's reasoning-capable model: $1.25/$2.50 per 1M input/output tokens, 1M token context window.
#5Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview is Google's reasoning-capable model: $2/$12 per 1M input/output tokens, 1.0M token context window, 54.2% on SWE-Bench Pro.