Kimi K3 (thinking) vs Grok 4.5
Should you write with Kimi K3 (thinking) or Grok 4.5? 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. Kimi K3 (thinking) leads overall, 87.2 to 81.9.
The verdict
Kimi K3 (thinking) is well ahead here: #41 against #76, a gap of about 480 Elo, and a clean sweep of the nine metrics. Length Adherence is Grok 4.5's biggest problem, about thirteen points behind, and its hook trails by seven. Grok 4.5 is the faster model, under a minute a script, and cheaper at about $0.063 against $0.095. That saving is small next to the quality gap, and Kimi is open weights. On xAI's side, Grok 4.7 (high) is the model worth testing for scripts.
Pick Kimi K3 (thinking) when you want strong openings and on-length scripts for under a dime.
Pick Grok 4.5 when raw speed matters more than the script itself.
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 Kimi K3 (thinking), orange is Grok 4.5, 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, Length Adherence does the most to put Kimi K3 (thinking) ahead: it leads there by 13.1 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. The lead has a price: Kimi K3 (thinking) costs about 1.5x as much per script as Grok 4.5.
| Kimi K3 (thinking) | Grok 4.5 | |
|---|---|---|
| Overall / 100 | 87.2 | 81.9 |
| Writing Elo | 2098 | 1618 |
| Score spread across drafts (± overall std) | 1.550 | 2.950 |
| Cost per script (USD) | 0.095 | 0.063 |
| Avg time per script (min) | 1.2 | 0.9 |
| Open weights | Yes | 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: Kimi K3 (thinking) · Grok 4.5. The whole scoring pipeline is on the methodology page.
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