Model Comparison
Claude Fable 5.1 vs GPT-6.1 Terra
Claude Fable 5.1 (max effort) leads GPT-6.1 Terra (max) by 601 Elo, and their 95% ranges sit 526 Elo apart. Even Claude Fable 5.1's lowest-rated configuration, Claude Fable 5.1 (high), ranks above GPT-6.1 Terra (max). Among 84 models, each ranked by its best configuration, Claude Fable 5.1 is #3 and GPT-6.1 Terra is #23. Cost per script: $3.56 for Claude Fable 5.1 (max effort) and $0.079 for GPT-6.1 Terra (max).
Last updated , from board data generated at 20:15 UTC.
Picks and Verdict
PickClaude Fable 5.1
Claude Fable 5.1 (max effort)
Pick Claude Fable 5.1 (max effort) for the script that has to sound right, 601 Elo above Terra's best at $3.56 and 12.3 minutes a script.
PickGPT-6.1 Terra
GPT-6.1 Terra (low)
Pick GPT-6.1 Terra (low) for cheap first drafts at $0.027 a script and about half a minute, since its individual Elo range overlaps Terra's higher effort levels.
This one isn't close on writing. Claude Fable 5.1 is the #3 model of 84 and GPT-6.1 Terra the #23 model, each ranked by its best setting, and Claude Fable 5.1 (max effort) sits 601 Elo above GPT-6.1 Terra (max), with 95% ranges 526 Elo apart. Even Fable at high clears every Terra row by a wide margin. The thinking levels behave in opposite ways. On Fable, going from high to max adds 205 Elo for nearly twice the cost, and those two ranges sit well apart, so the extra effort pays. On Terra, all five levels land within 25 Elo of each other with overlapping ranges, so I would run low: $0.027 a script in about half a minute, against $0.079 and 1.8 minutes at max. Fable at max costs $3.56 and takes 12.3 minutes. The gap shows up in voice and structure, with Fable 7.8 points ahead on Tone & Voice Match and 7.4 on YouTube Best Practices at the top settings. Terra's one edge is slop, about a point better. I'd use Fable at max for the script I publish and Terra at low for throwaway first drafts.
Disclosure: Claude Fable 5.1 and GPT-6.1 Terra each come from the same lab as one of the judges (Claude Opus 5.5 and GPT-6.1 Sol). 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 5.1 and GPT-6.1 Terra, 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 5.1 (max effort) | 2524 | 2485 to 2562 | 84.5 | $3.56 | 12.3 min | #4 |
| Claude Fable 5.1 (high) | 2319 | 2259 to 2372 | 83.4 | $1.85 | 6.3 min | #9 |
| GPT-6.1 Terra (max) | 1923 | 1884 to 1959 | 80.3 | $0.079 | 1.8 min | #43 |
| GPT-6.1 Terra (high) | 1922 | 1881 to 1958 | 80.3 | $0.027 | 0.5 min | #44 |
| GPT-6.1 Terra (low) | 1920 | 1879 to 1961 | 80.2 | $0.027 | 0.5 min | #46 |
| GPT-6.1 Terra (xhigh) | 1906 | 1869 to 1944 | 80.1 | $0.028 | 0.5 min | #48 |
| GPT-6.1 Terra (medium) | 1898 | 1852 to 1942 | 79.9 | $0.027 | 0.5 min | #49 |
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 5.1 (max effort) leads GPT-6.1 Terra (max) by 601 Elo, and their 95% ranges do not overlap (2485 to 2562 against 1884 to 1959), which is strong evidence for that order.
- Every Claude Fable 5.1 Configuration Ranks Higher. Both Claude Fable 5.1 configurations rank above all five GPT-6.1 Terra configurations: the lowest-rated, Claude Fable 5.1 (high) at Elo 2319, still beats GPT-6.1 Terra (max) at Elo 1923. Their 95% ranges do not overlap.
- Lowest Thinking Levels Head to Head. At their lowest thinking levels, Claude Fable 5.1 (high) at Elo 2319 and $1.85 per script leads GPT-6.1 Terra (low) at Elo 1920 and $0.027 per script by 399 Elo. Their 95% ranges do not overlap.
- Same Level Name, Side by Side. Claude Fable 5.1 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 5.1 Configuration Above GPT-6.1 Terra's Best. The cheapest Claude Fable 5.1 configuration with a higher Writing Elo than GPT-6.1 Terra (max), at Elo 1923 and $0.079 per script, is Claude Fable 5.1 (high), at Elo 2319 and $1.85 per script. It costs about 23 times as much per script.
- Lowest to Highest Thinking Level. Claude Fable 5.1 moves +205 Elo from high to max effort, at about 1.9 times the cost per script. GPT-6.1 Terra moves +3 Elo from low to max, at about 2.9 times the cost per script.
Writing Elo at Each Shared Level Name
| Level | Claude Fable 5.1 | GPT-6.1 Terra | Gap | 95% Ranges |
|---|---|---|---|---|
| high | 2319 | 1922 | +397 | Separate |
| max | 2524 | 1923 | +601 | Separate |
Gap is Claude Fable 5.1 minus GPT-6.1 Terra 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 5.1 (max effort) scores higher on eight of the nine metrics and GPT-6.1 Terra (max) on one. Weighted by each metric's share of the Writing Score, Tone & Voice Match does the most to put Claude Fable 5.1 (max effort) ahead, with a 7.8-point lead on that metric. The weight beside each metric is its share of the Writing Score.
Consistency Across Drafts
| Claude Fable 5.1 (max effort) | GPT-6.1 Terra (max) | |
|---|---|---|
| Score spread across drafts (±) | 1.13 | 1.68 |
| Lowest script score | 82.8 Script 10 | 77.9 Script 10 |
| Highest script score | 86.2 Script 9 | 83.2 Script 9 |
| Range across scripts | 3.4 | 5.3 |
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 5.1 (max effort) minus GPT-6.1 Terra (max), and the higher score is in bold.
| Script | Claude Fable 5.1 (max effort) | GPT-6.1 Terra (max) | Gap |
|---|---|---|---|
| Script 1 opinion / warning explainer | 83.3 | 80.2 | +3.1 |
| Script 2 news-analysis / skeptical explainer | 83.8 | 80.7 | +3.1 |
| Script 3 personal roadmap / opinion | 84.0 | 80.4 | +3.6 |
| Script 4 short explainer | 85.2 | 79.6 | +5.6 |
| Script 5 news-analysis / opinion explainer | 84.9 | 80.1 | +4.8 |
| Script 6 founder announcement / personal origin story | 85.0 | 82.2 | +2.8 |
| Script 7 personal technical walkthrough / agentic workflow case study | 85.3 | 79.9 | +5.4 |
| Script 8 product release announcement / personal observation | 84.7 | 79.1 | +5.6 |
| Script 9 career guide / hiring analysis | 86.2 | 83.2 | +3.0 |
| Script 10 engineering process walkthrough / presentation adaptation | 82.8 | 77.9 | +4.9 |
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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