Grok 4.5 vs Gemini 3.1 Pro (default)
Should you write with Grok 4.5 or Gemini 3.1 Pro (default)? On this page the only thing that changes is the model. Both wrote their own version of the scripts behind 10 of my What's AI videos, five drafts per script, and three judges from three model families scored every draft blind, with my finished script as the reference. Grok 4.5 leads overall, 81.9 to 80.1.
The verdict
Grok 4.5 wins and it's cheaper, which makes this simple. It ranks #76 against #94, at $0.063 per script against $0.143 for Gemini 3.1 Pro (default). Grok's edge is substance and voice match, close to four points each. Gemini scores slightly higher on the hook and lands closer to the target length. To be fair to both, neither is where I'd start for a script I care about: they sit well below the top of the board, where even open models like GLM-5.3 score far higher.
Pick Grok 4.5 for more substance and a better voice match at a lower price.
Pick Gemini 3.1 Pro (default) if you're already on Google's stack and care more about the hook and length control.
How to read these numbers
Overall vs Elo. Overall is the weighted rubric score. Elo compares each model's five-draft average with every other model's, script by script, and counts gaps inside run-to-run noise as draws, so it rewards winning often and can disagree with overall. My own scripts score 90.9 on the same rubric, not a literal 100. Right now 2 of 167 ranked configurations reach it. A model above that line writes at that level on this rubric. That's not the same as beating my script line for line.
Reading the Elo intervals. Each 95% range comes from resampling every model's recorded run scores on each task and re-ranking. Comparing these separate ranges does not test the Elo gap between two models: far apart is strong evidence, and overlap isn't a tie. The tasks stay fixed, so the ranges say nothing about new tasks (the long version).
Metric by metric: where the gap comes from
Blue is Grok 4.5, orange is Gemini 3.1 Pro (default), and the solid bar takes the metric. The weight under each name is how much it counts toward the overall. Weighted by how much each metric counts, Tone & Voice Match does the most to put Grok 4.5 ahead: it leads there by 3.7 points. If you care about one thing, say voice or length, go straight to that row.
Cost, speed, and consistency
Quality is half the decision. The other half is what each script costs you, how long you wait, and how often you get a bad draft. Grok 4.5 is ahead and it's also the cheaper one: Gemini 3.1 Pro (default) costs about 2.3x as much per script.
| Grok 4.5 | Gemini 3.1 Pro (default) | |
|---|---|---|
| Overall / 100 | 81.9 | 80.1 |
| Writing Elo | 1618 | 1465 |
| Score spread across drafts (± overall std) | 2.950 | 2.580 |
| Cost per script (USD) | 0.063 | 0.143 |
| Avg time per script (min) | 0.9 | 1.3 |
| Open weights | No | No |
Green wins the row, and for spread, cost and time, lower wins. Cost is one script at recorded list prices, uncached and without judging, so your real bill will differ. Spread is how much the overall score moves across a model's drafts, and time is the average time to get one accepted script, retries included.
Want the script-by-script detail? Full scorecards: Grok 4.5 · Gemini 3.1 Pro (default). The whole scoring pipeline is on the methodology page.
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