Model Comparison
GPT-6 Astra vs GPT-5.6 Terra
GPT-6 Astra (max) leads GPT-5.6 Terra (ultra) by 111 Elo, and their 95% ranges sit 32 Elo apart. Among 78 models, each ranked by its best configuration, GPT-6 Astra is #11 and GPT-5.6 Terra is #13. Cost per script: $1.15 for GPT-6 Astra (max) and $0.275 for GPT-5.6 Terra (ultra).
Last updated , from board data generated at 01:13 UTC.
Picks and Verdict
PickGPT-6 Astra
GPT-6 Astra (medium)
Pick GPT-6 Astra (medium) for clean drafts at $0.262 a script, since max costs $1.15 for 182 more Elo.
PickGPT-5.6 Terra
GPT-5.6 Terra (medium)
Pick GPT-5.6 Terra (medium) for the drafts you write in bulk, because $0.062 a script is less than a quarter of what GPT-6 Astra (medium) costs and the board can't separate the two.
Each model here has a top setting I wouldn't run, so I read this page from the medium row. At the top, GPT-6 Astra (max) leads GPT-5.6 Terra (ultra) by 111 Elo, with 95% ranges that sit 32 Elo apart, strong evidence for that order. By best setting, that's the #11 model of 78 against the #13 model. But Terra's ultra is 76 Elo above GPT-5.6 Terra (medium) with overlapping ranges, so the board can't separate them, and it costs more than four times as much and takes almost six times as long. For about what ultra costs, GPT-6 Astra (medium) is back in under two minutes. Astra's max does earn its rating, 182 Elo above that, but $1.15 and more than nine minutes is a lot for one draft. Medium against medium, Astra leads by 5 Elo with overlapping ranges, so the board can't separate those either, and Terra costs $0.062 against $0.262. Astra's drafts come back about five points cleaner on slop, and Terra sounds a little closer on tone. I'd draft with Terra at medium and pay for Astra at medium when I want a cleaner one.
Disclosure: both models come from the same lab as one of the four judges, GPT-6.1 Sol. 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 GPT-6 Astra and GPT-5.6 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.
- 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 |
|---|---|---|---|---|---|---|
| GPT-6 Astra (max) | 2185 | 2145 to 2223 | 82.3 | $1.15 | 9.2 min | #21 |
| GPT-5.6 Terra (ultra) | 2074 | 2035 to 2113 | 81.4 | $0.275 | 8.0 min | #25 |
| GPT-6 Astra (medium) | 2003 | 1968 to 2035 | 80.7 | $0.262 | 1.5 min | #32 |
| GPT-5.6 Terra (medium) | 1998 | 1952 to 2041 | 80.7 | $0.062 | 1.4 min | #33 |
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. GPT-6 Astra (max) leads GPT-5.6 Terra (ultra) by 111 Elo, and their 95% ranges do not overlap (2145 to 2223 against 2035 to 2113), which is strong evidence for that order.
- Lowest Thinking Levels Head to Head. At their lowest thinking levels, GPT-6 Astra (medium) at Elo 2003 and $0.262 per script leads GPT-5.6 Terra (medium) at Elo 1998 and $0.062 per script by 5 Elo. Their 95% ranges overlap, so the board cannot separate them.
- Same Level Name, Side by Side. At medium, the one level name both models use, GPT-6 Astra has the higher Writing Elo: 2003 against 1998. Their 95% ranges overlap there. Level names come from each provider, so the same name does not promise the same reasoning budget.
- Cheapest GPT-6 Astra Configuration Above GPT-5.6 Terra's Best. The cheapest GPT-6 Astra configuration with a higher Writing Elo than GPT-5.6 Terra (ultra), at Elo 2074 and $0.275 per script, is GPT-6 Astra (max), at Elo 2185 and $1.15 per script. It costs about 4.2 times as much per script.
- Lowest to Highest Thinking Level. GPT-6 Astra moves +182 Elo from medium to max, at about 4.4 times the cost per script. GPT-5.6 Terra moves +76 Elo from medium to ultra, at about 4.4 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
GPT-6 Astra (max) scores higher on seven of the nine metrics and GPT-5.6 Terra (ultra) on two. Weighted by each metric's share of the Writing Score, Length Adherence does the most to put GPT-6 Astra (max) ahead, with a 4.6-point lead on that metric. The weight beside each metric is its share of the Writing Score.
Consistency Across Drafts
| GPT-6 Astra (max) | GPT-5.6 Terra (ultra) | |
|---|---|---|
| Score spread across drafts (±) | 1.87 | 1.38 |
| Lowest script score | 80.6 Script 1 | 79.8 Script 4 |
| Highest script score | 85.8 Script 9 | 83.0 Script 6 |
| Range across scripts | 5.2 | 3.2 |
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 GPT-6 Astra (max) minus GPT-5.6 Terra (ultra), and the higher score is in bold.
| Script | GPT-6 Astra (max) | GPT-5.6 Terra (ultra) | Gap |
|---|---|---|---|
| Script 1 opinion / warning explainer | 80.6 | 81.1 | -0.5 |
| Script 2 news-analysis / skeptical explainer | 82.0 | 82.1 | -0.1 |
| Script 3 personal roadmap / opinion | 84.3 | 82.5 | +1.8 |
| Script 4 short explainer | 82.7 | 79.8 | +2.9 |
| Script 5 news-analysis / opinion explainer | 81.3 | 82.2 | -0.9 |
| Script 6 founder announcement / personal origin story | 83.6 | 83.0 | +0.6 |
| Script 7 personal technical walkthrough / agentic workflow case study | 81.6 | 80.6 | +1.0 |
| Script 8 product release announcement / personal observation | 80.6 | 80.3 | +0.3 |
| Script 9 career guide / hiring analysis | 85.8 | 81.8 | +4.0 |
| Script 10 engineering process walkthrough / presentation adaptation | 80.7 | 80.6 | +0.1 |
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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