Model Comparison
Claude Opus 5.5 vs Claude Sonnet 5.5
Claude Opus 5.5 (max effort) leads Claude Sonnet 5.5 (max effort) by 227 Elo, and their 95% ranges sit 102 Elo apart. Among 78 models, each ranked by its best configuration, Claude Opus 5.5 is #1 and Claude Sonnet 5.5 is #2. Cost per script: $2.58 for Claude Opus 5.5 (max effort) and $1.38 for Claude Sonnet 5.5 (max effort).
Last updated , from board data generated at 01:13 UTC.
Picks and Verdict
PickClaude Opus 5.5
Claude Opus 5.5 (xhigh)
Pick Claude Opus 5.5 (xhigh) for every serious script, since it reaches the top Writing Elo on this page and costs $1.00, less than Sonnet's best.
PickClaude Sonnet 5.5
Claude Sonnet 5.5 (high)
Pick Claude Sonnet 5.5 (high) when you need lots of drafts fast, at $0.092 a script and about a minute each.
Claude Opus 5.5 wins at every level name these two share, low through max, with separate ranges each time. These are the #1 model of 78 and the #2 model, each ranked by its best setting, and Opus at xhigh sits 227 Elo above Claude Sonnet 5.5 (max effort). It's cheaper too: $1.00 a script against $1.38, in less than half the time. The more useful finding sits lower. Sonnet's best lands just above Opus at high, medium and low, but all three ranges overlap it. So Claude Opus 5.5 (low) writes at a level the board can't separate from Sonnet's best, for $0.243 and about a minute and a half, where Sonnet at max effort takes around fourteen. Inside Opus, I'd skip max effort, which costs about two and a half times xhigh and lands on the same Writing Elo. Sonnet does gain far more from thinking, +753 Elo from low to max effort against +295 for Opus, and its top two settings write the steadiest drafts on this page. For anything I'd record, though, I'd run Opus at xhigh.
Disclosure: both models come from the same lab as one of the four judges, Claude Opus 5.5. The other judges sit outside that lab, so neither is 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 Claude Sonnet 5.5, 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 | Configuration Rank |
|---|---|---|---|---|---|---|
| Claude Opus 5.5 (max effort) | 2788 | 2716 to 2845 | 85.9 | $2.58 | 17.5 min | #1 |
| Claude Opus 5.5 (xhigh) | 2788 | 2727 to 2851 | 85.8 | $1.00 | 6.7 min | #2 |
| Claude Sonnet 5.5 (max effort) | 2561 | 2504 to 2614 | 84.6 | $1.38 | 14.3 min | #3 |
| Claude Opus 5.5 (high) | 2536 | 2486 to 2573 | 84.6 | $0.328 | 2.1 min | #5 |
| Claude Opus 5.5 (medium) | 2520 | 2469 to 2576 | 84.5 | $0.310 | 1.9 min | #6 |
| Claude Opus 5.5 (low) | 2493 | 2436 to 2536 | 84.3 | $0.243 | 1.5 min | #7 |
| Claude Sonnet 5.5 (xhigh) | 2348 | 2304 to 2383 | 83.2 | $0.302 | 3.1 min | #10 |
| Claude Sonnet 5.5 (high) | 2040 | 1984 to 2087 | 81.0 | $0.092 | 1.0 min | #27 |
| Claude Sonnet 5.5 (medium) | 1856 | 1812 to 1900 | 79.4 | $0.065 | 0.6 min | #47 |
| Claude Sonnet 5.5 (low) | 1808 | 1771 to 1843 | 78.9 | $0.061 | 0.7 min | #50 |
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.
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 (max effort) leads Claude Sonnet 5.5 (max effort) by 227 Elo, and their 95% ranges do not overlap (2716 to 2845 against 2504 to 2614), which is strong evidence for that order.
- Lowest Thinking Levels Head to Head. At their lowest thinking levels, Claude Opus 5.5 (low) at Elo 2493 and $0.243 per script leads Claude Sonnet 5.5 (low) at Elo 1808 and $0.061 per script by 685 Elo. Their 95% ranges do not overlap.
- Same Level Name, Side by Side. Claude Opus 5.5 has the higher Writing Elo at every level name both models use: low, medium, high, xhigh, and max. The 95% ranges do not overlap at any of them. Level names come from each provider, so the same name does not promise the same reasoning budget.
- Cheapest Configuration Overlapping the Top One. Claude Opus 5.5 (xhigh), at $1.00 per script, is the cheapest configuration whose 95% range overlaps that of Claude Opus 5.5 (max effort), at $2.58 per script: 2727 to 2851 against 2716 to 2845, so the board cannot separate them. Claude Opus 5.5 (max effort) costs about 2.6 times as much per script.
- Cheapest Claude Opus 5.5 Configuration Above Claude Sonnet 5.5's Best. The cheapest Claude Opus 5.5 configuration with a higher Writing Elo than Claude Sonnet 5.5 (max effort), at Elo 2561 and $1.38 per script, is Claude Opus 5.5 (xhigh), at Elo 2788 and $1.00 per script. It costs less than the configuration it beats.
- Lowest to Highest Thinking Level. Claude Opus 5.5 moves +295 Elo from low to max effort, at about 11 times the cost per script. Claude Sonnet 5.5 moves +753 Elo from low to max effort, at about 23 times the cost per script.
Writing Elo at Each Shared Level Name
| Level | Claude Opus 5.5 | Claude Sonnet 5.5 | Gap | 95% Ranges |
|---|---|---|---|---|
| low | 2493 | 1808 | +685 | Separate |
| medium | 2520 | 1856 | +664 | Separate |
| high | 2536 | 2040 | +496 | Separate |
| xhigh | 2788 | 2348 | +440 | Separate |
| max | 2788 | 2561 | +227 | Separate |
Gap is Claude Opus 5.5 minus Claude Sonnet 5.5 at the same level name, using each model's highest-rated configuration at that level.
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 (max effort) scores higher on eight of the nine metrics and Claude Sonnet 5.5 (max effort) on one. Weighted by each metric's share of the Writing Score, Tone & Voice Match does the most to put Claude Opus 5.5 (max effort) ahead, with a 2.3-point lead on that metric. The weight beside each metric is its share of the Writing Score.
Consistency Across Drafts
| Claude Opus 5.5 (max effort) | Claude Sonnet 5.5 (max effort) | |
|---|---|---|
| Score spread across drafts (±) | 1.44 | 1.22 |
| Lowest script score | 83.6 Script 10 | 83.0 Script 10 |
| Highest script score | 87.3 Script 7 | 86.7 Script 9 |
| Range across scripts | 3.7 | 3.7 |
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 (max effort) minus Claude Sonnet 5.5 (max effort), and the higher score is in bold.
| Script | Claude Opus 5.5 (max effort) | Claude Sonnet 5.5 (max effort) | Gap |
|---|---|---|---|
| Script 1 opinion / warning explainer | 84.6 | 84.2 | +0.4 |
| Script 2 news-analysis / skeptical explainer | 85.3 | 84.8 | +0.5 |
| Script 3 personal roadmap / opinion | 86.5 | 84.0 | +2.5 |
| Script 4 short explainer | 87.0 | 85.0 | +2.0 |
| Script 5 news-analysis / opinion explainer | 85.9 | 84.8 | +1.1 |
| Script 6 founder announcement / personal origin story | 86.3 | 84.6 | +1.7 |
| Script 7 personal technical walkthrough / agentic workflow case study | 87.3 | 85.0 | +2.3 |
| Script 8 product release announcement / personal observation | 85.5 | 83.9 | +1.6 |
| Script 9 career guide / hiring analysis | 87.3 | 86.7 | +0.6 |
| Script 10 engineering process walkthrough / presentation adaptation | 83.6 | 83.0 | +0.6 |
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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