Model Comparison
Claude Fable 5.2 vs Claude Fable 5.1
Claude Fable 5.2 (xhigh) leads Claude Fable 5.1 (max effort) by 188 Elo, and their 95% ranges sit 107 Elo apart. Among 87 models, each ranked by its best configuration, Claude Fable 5.2 is #2 and Claude Fable 5.1 is #4. Cost per script: $2.22 for Claude Fable 5.2 (xhigh) and $3.56 for Claude Fable 5.1 (max effort).
Last updated , from board data generated at 17:52 UTC.
Picks and Verdict
PickClaude Fable 5.2
Claude Fable 5.2 (xhigh)
Pick Claude Fable 5.2 (xhigh) as the upgrade, since it leads Fable 5.1's best by 188 Elo with separate ranges at $2.22 a script, less than the old max effort's $3.56.
PickClaude Fable 5.1
Claude Fable 5.1 (max effort)
Pick Claude Fable 5.1 (max effort) if steady drafts matter most, since its spread of 1.13 points is the lowest on this page, at $3.56 a script.
Claude Fable 5.2 replaces Claude Fable 5.1 at both of the old model's settings, and each swap I'd make costs less. Claude Fable 5.2 (xhigh), the new model's best setting, leads Claude Fable 5.1 (max effort) by 188 Elo with 95% ranges that don't overlap, at $2.22 and 7.4 minutes a script against $3.56 and 12.3: the #2 model of 87 against the #4 model, each ranked by its best configuration. At high the gap grows to 229 Elo, and the new model is cheaper and faster there too, $1.22 and 4.0 minutes against $1.85 and 6.3. Even Claude Fable 5.2 (low) sits 133 Elo above Fable 5.1 at high with separate ranges. The close comparison is Claude Fable 5.2 (high) against Fable 5.1 at max effort: 26 Elo higher on the point estimates, overlapping ranges, about a third of the price. I'd skip the new max effort: $5.75 and 19.9 minutes for 27 Elo less than xhigh. Fable 5.1 gets 203 Elo from high to max effort for about 1.9 times the cost. The old max still writes the steadiest drafts on this page and ties the new xhigh on tone. I'd move to Fable 5.2 anyway: high for everyday scripts, xhigh for the ones I record.
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 Fable 5.2 and Claude Fable 5.1, 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.
- Each bar describes one configuration. Overlap alone does not establish a tie or decide their order. Comparing these ranges does not directly test the difference between a pair.
- 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 Fable 5.2 (xhigh) | 2673 | 2630 to 2717 | 85.6 | $2.22 | 7.4 min | #3 |
| Claude Fable 5.2 (max effort) | 2646 | 2599 to 2689 | 85.5 | $5.75 | 19.9 min | #4 |
| Claude Fable 5.2 (high) | 2511 | 2455 to 2555 | 84.8 | $1.22 | 4.0 min | #5 |
| Claude Fable 5.1 (max effort) | 2485 | 2447 to 2523 | 84.5 | $3.56 | 12.3 min | #7 |
| Claude Fable 5.2 (medium) | 2422 | 2370 to 2469 | 84.3 | $0.561 | 1.8 min | #11 |
| Claude Fable 5.2 (low) | 2415 | 2370 to 2454 | 84.1 | $0.460 | 1.4 min | #12 |
| Claude Fable 5.1 (high) | 2282 | 2219 to 2344 | 83.4 | $1.85 | 6.3 min | #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.
Computed Findings Across Thinking Levels
Each finding is computed from the configurations above. The 95% ranges describe individual configurations; overlap alone establishes neither a tie nor an order for a pair.
- Best Configurations Head to Head. Claude Fable 5.2 (xhigh) leads Claude Fable 5.1 (max effort) by 188 Elo, and their 95% ranges do not overlap (2630 to 2717 against 2447 to 2523), which is strong evidence for that order.
- Lowest Thinking Levels Head to Head. At their lowest thinking levels, Claude Fable 5.2 (low) at Elo 2415 and $0.460 per script leads Claude Fable 5.1 (high) at Elo 2282 and $1.85 per script by 133 Elo. Their 95% ranges do not overlap.
- Same Level Name, Side by Side. Claude Fable 5.2 has the higher Writing Elo at every level name both models use: high 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 Claude Fable 5.2 Configuration Above Claude Fable 5.1's Best. The cheapest Claude Fable 5.2 configuration with a higher Writing Elo than Claude Fable 5.1 (max effort), at Elo 2485 and $3.56 per script, is Claude Fable 5.2 (high), at Elo 2511 and $1.22 per script. Their 95% ranges overlap. It costs less than the configuration it beats.
- Lowest to Highest Thinking Level. Claude Fable 5.2 moves +231 Elo from low to max effort, at about 13 times the cost per script. Claude Fable 5.1 moves +203 Elo from high to max effort, at about 1.9 times the cost per script.
Writing Elo at Each Shared Level Name
| Level | Claude Fable 5.2 | Claude Fable 5.1 | Gap | 95% Ranges |
|---|---|---|---|---|
| high | 2511 | 2282 | +229 | Separate |
| max | 2646 | 2485 | +161 | Separate |
Gap is Claude Fable 5.2 minus Claude Fable 5.1 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 Fable 5.2 (xhigh) scores higher on eight of the nine metrics, and the other one is a tie. Weighted by each metric's share of the Writing Score, Substance, Accuracy & Value does the most to put Claude Fable 5.2 (xhigh) ahead, with a 2.2-point lead on that metric. The weight beside each metric is its share of the Writing Score.
Consistency Across Drafts
| Claude Fable 5.2 (xhigh) | Claude Fable 5.1 (max effort) | |
|---|---|---|
| Score spread across drafts (±) | 1.44 | 1.13 |
| Lowest script score | 83.6 Script 10 | 82.8 Script 10 |
| Highest script score | 88.0 Script 9 | 86.2 Script 9 |
| Range across scripts | 4.4 | 3.4 |
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 Fable 5.2 (xhigh) minus Claude Fable 5.1 (max effort), and the higher score is in bold.
| Script | Claude Fable 5.2 (xhigh) | Claude Fable 5.1 (max effort) | Gap |
|---|---|---|---|
| Script 1 opinion / warning explainer | 83.7 | 83.3 | +0.4 |
| Script 2 news-analysis / skeptical explainer | 85.4 | 83.8 | +1.6 |
| Script 3 personal roadmap / opinion | 85.5 | 84.0 | +1.5 |
| Script 4 short explainer | 85.4 | 85.2 | +0.2 |
| Script 5 news-analysis / opinion explainer | 86.1 | 84.9 | +1.2 |
| Script 6 founder announcement / personal origin story | 85.9 | 85.0 | +0.9 |
| Script 7 personal technical walkthrough / agentic workflow case study | 87.3 | 85.3 | +2.0 |
| Script 8 product release announcement / personal observation | 85.1 | 84.7 | +0.4 |
| Script 9 career guide / hiring analysis | 88.0 | 86.2 | +1.8 |
| Script 10 engineering process walkthrough / presentation adaptation | 83.6 | 82.8 | +0.8 |
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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