Model Comparison
Claude Opus 5.5 vs Kimi K3.1 Pro
Claude Opus 5.5 (xhigh) leads Kimi K3.1 Pro (max) by 566 Elo, and their 95% ranges sit 450 Elo apart. Even Claude Opus 5.5's lowest-rated configuration, Claude Opus 5.5 (low), ranks above Kimi K3.1 Pro (max). Among 83 models, each ranked by its best configuration, Claude Opus 5.5 is #1 and Kimi K3.1 Pro is #7. Cost per script: $1.00 for Claude Opus 5.5 (xhigh) and $0.251 for Kimi K3.1 Pro (max).
Last updated , from board data generated at 22:06 UTC.
Picks and Verdict
PickClaude Opus 5.5
Claude Opus 5.5 (low)
Pick Claude Opus 5.5 (low) for everyday drafts, since it beats Kimi K3.1 Pro (max) by 266 Elo with separate ranges for $0.243 a script, a little less than Kimi.
PickKimi K3.1 Pro
Kimi K3.1 Pro (max)
Pick Kimi K3.1 Pro (max) if you want a second provider in the pipeline, since it matches Claude Opus 5.5 (xhigh) on substance, hooks and visual cues at $0.251 a script.
Claude Opus 5.5 beats Kimi K3.1 Pro at every setting, and its cheapest one even costs less. Claude Opus 5.5 (low) sits 266 Elo above Kimi K3.1 Pro (max) with separate ranges, at $0.243 a script against $0.251, and it's done in a minute and a half where Kimi takes 5.5. At the top, the #1 model of 83 meets the #7 model with 566 Elo between Claude Opus 5.5 (xhigh) and Kimi, and xhigh wins all ten scripts. Kimi has no lower setting to try, since the board runs it only at max, Moonshot's default. On the Opus side I'd skip max effort: it costs $2.58 against $1.00 for xhigh, takes 17.5 minutes and rates no higher. Most of the gap is voice, with Opus at xhigh more than five points ahead on tone and on craft. Kimi holds its own elsewhere. It's level with xhigh on substance and visual cues and half a point ahead on hooks, which is impressive at that price. Moonshot calls it open-weight, but the weights aren't published yet, so you can't host it yourself today. I'd run Opus at low for drafts and at xhigh for the script I film.
Disclosure: Claude Opus 5.5 comes from the same lab as one of the four judges, Claude Opus 5.5. The other three sit outside its lab, so it is never scored by its own lab alone (how the panel works). The judge analysis measures how much each judge favors its own lab.
How to Read the Writing Score, Writing Elo and 95% Ranges
Writing Score and Writing Elo. The Writing Score (0 to 100) is the weighted average of the nine metric scores: seven from the judges, Length Adherence from code and the Slop Score half from each. The Writing Elo is a rating from pairwise comparisons: on each script, each configuration's average across its drafts is compared with every other configuration's, and gaps within the draft-to-draft variation count as draws. Elo rewards winning often, so the two can put configurations in a different order.
Elo ranges. Each 95% range shows how far a configuration's Elo could move if the drafts had come out slightly differently. It comes from resampling every configuration's recorded draft scores on each reference script and ranking again. Comparing two separate ranges does not test the Elo gap between them: ranges far apart are strong evidence for the order, and overlapping ranges do not mean a tie. The reference scripts stay fixed, so the ranges say nothing about new scripts. The methodology page has the full description.
All Thinking Levels of Both Models
Every ranked configuration of Claude Opus 5.5 and Kimi K3.1 Pro, scored on the same 10 scripts by the same four judges.
- Each row is one configuration: the model at one thinking level. The dot is its Writing Elo, a rating from pairwise comparisons of the scores on each script, and the bar is its 95% range: how far that Elo could move if the drafts had come out slightly differently.
- When two bars overlap, the board cannot order those two configurations. Bars far apart are strong evidence for the order.
- The table under the chart lists the same configurations in the same order and adds the Writing Score (the 0 to 100 consensus of the judges and code), cost, time and configuration rank (the place among all configurations on the board).
Shaded rows are the configurations chosen for the metric comparison below.
| Configuration | Writing Elo | 95% Range | Writing Score | Cost / Script | Time / Script | Reasoning Tokens | Configuration Rank |
|---|---|---|---|---|---|---|---|
| Claude Opus 5.5 (xhigh) | 2771 | 2696 to 2839 | 85.8 | $1.00 | 6.7 min | N/A | #1 |
| Claude Opus 5.5 (max effort) | 2769 | 2703 to 2836 | 85.9 | $2.58 | 17.5 min | N/A | #2 |
| Claude Opus 5.5 (high) | 2517 | 2462 to 2556 | 84.6 | $0.328 | 2.1 min | N/A | #5 |
| Claude Opus 5.5 (medium) | 2494 | 2440 to 2551 | 84.5 | $0.310 | 1.9 min | N/A | #6 |
| Claude Opus 5.5 (low) | 2471 | 2418 to 2517 | 84.3 | $0.243 | 1.5 min | N/A | #7 |
| Kimi K3.1 Pro (max) | 2205 | 2166 to 2246 | 82.5 | $0.251 | 5.5 min | 19,487 | #14 |
Cost is one script at the API list price of the route used, uncached and without judging. Time is the average for one accepted script, retries included. N/A under Reasoning Tokens means the board has no separate reasoning count for that route.
Computed Findings Across Thinking Levels
Each finding is computed from the configurations above. Where two 95% ranges overlap, the board cannot order those two configurations.
- Best Configurations Head to Head. Claude Opus 5.5 (xhigh) leads Kimi K3.1 Pro (max) by 566 Elo, and their 95% ranges do not overlap (2696 to 2839 against 2166 to 2246), which is strong evidence for that order.
- Every Claude Opus 5.5 Configuration Ranks Higher. All five Claude Opus 5.5 configurations rank above Kimi K3.1 Pro (max), the only Kimi K3.1 Pro configuration on the board: even Claude Opus 5.5 (low) at Elo 2471 beats its Elo of 2205. Their 95% ranges do not overlap.
- Same Level Name, Side by Side. At max, the one level name both models use, Claude Opus 5.5 has the higher Writing Elo: 2769 against 2205. Their 95% ranges do not overlap there. Level names come from each provider, so the same name does not promise the same reasoning budget.
- Cheapest Claude Opus 5.5 Configuration Above Kimi K3.1 Pro's Best. The cheapest Claude Opus 5.5 configuration with a higher Writing Elo than Kimi K3.1 Pro (max), at Elo 2205 and $0.251 per script, is Claude Opus 5.5 (low), at Elo 2471 and $0.243 per script. It costs less than the configuration it beats.
- Lowest to Highest Thinking Level. Claude Opus 5.5 moves +298 Elo from low to max effort, at about 11 times the cost per script.
Two Chosen Configurations Compared
Pick one configuration of each model to compare their metric scores, consistency across drafts and per-script scores. Each menu starts on the model's best configuration.
Scores by Metric
Claude Opus 5.5 (xhigh) scores higher on seven of the nine metrics and Kimi K3.1 Pro (max) on one, with one tie. Weighted by each metric's share of the Writing Score, Tone & Voice Match does the most to put Claude Opus 5.5 (xhigh) ahead, with a 5.5-point lead on that metric. The weight beside each metric is its share of the Writing Score.
Consistency Across Drafts
| Claude Opus 5.5 (xhigh) | Kimi K3.1 Pro (max) | |
|---|---|---|
| Score spread across drafts (±) | 1.43 | 1.65 |
| Lowest script score | 84.3 Script 10 | 80.4 Script 7 |
| Highest script score | 87.9 Script 7 | 85.5 Script 9 |
| Range across scripts | 3.6 | 5.1 |
Spread is how much the Writing Score moves between a configuration's drafts, and lower is steadier. Green marks the better number in each row.
Scores by Script
Writing Score on each reference script. Gap is Claude Opus 5.5 (xhigh) minus Kimi K3.1 Pro (max), and the higher score is in bold.
| Script | Claude Opus 5.5 (xhigh) | Kimi K3.1 Pro (max) | Gap |
|---|---|---|---|
| Script 1 opinion / warning explainer | 84.4 | 81.3 | +3.1 |
| Script 2 news-analysis / skeptical explainer | 85.6 | 83.2 | +2.4 |
| Script 3 personal roadmap / opinion | 85.7 | 81.9 | +3.8 |
| Script 4 short explainer | 86.2 | 82.0 | +4.2 |
| Script 5 news-analysis / opinion explainer | 85.1 | 84.2 | +0.9 |
| Script 6 founder announcement / personal origin story | 85.6 | 83.0 | +2.6 |
| Script 7 personal technical walkthrough / agentic workflow case study | 87.9 | 80.4 | +7.5 |
| Script 8 product release announcement / personal observation | 85.8 | 82.1 | +3.7 |
| Script 9 career guide / hiring analysis | 87.9 | 85.5 | +2.4 |
| Script 10 engineering process walkthrough / presentation adaptation | 84.3 | 81.3 | +3.0 |
Scorecards and Thinking Pages
Each configuration name in the table above opens its own scorecard.
Compare With Another Model
Pick a second model. A pair with its own written match-up opens that page, and any other pair opens in the comparison tool.
Nearby Match-Ups by Best Writing Elo
Every configuration wrote five drafts for each of the same 10 briefs, from the same prompt. Generation was closed-book, with the prompt as the only source and no web search or other tools. Each judge scores every draft once: Claude Opus 5.5 at medium effort through the Claude Code subscription, GPT-6.1 Sol at medium reasoning through the Codex CLI, GLM 5.3 Flash through OpenRouter, and Jev 1.13, a typed judge from TypeSafe that answers each metric as a multiple-choice question. The channel's finished script is their reference for the voice, and it gets no score on the board itself.
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