GPT-5.6 Sol nearly matches Fable 5 on aggregated benchmarks at one-third the cost

OpenAI's new flagship model, GPT-5.6 Sol, performs almost as well as Fable 5 in benchmarks but costs only one-third as much.

According to the independent AI evaluation platform Artificial Analysis, GPT-5.6 Sol (max) scores 59 points on the Intelligence Index, just one point behind Claude Fable 5 (max). In Artificial Analysis's new Coding Agent Index, Sol (max) takes the top spot with 80 points when running in OpenAI's Codex environment, beating every other model. In the AA-Briefcase benchmark for realistic office tasks, Sol earns the highest "Presentation Elo" of all models but still trails Fable 5 in the overall ranking.

Above: In the Artificial Analysis Intelligence Index, Claude Fable 5 leads with 60 points, just ahead of GPT-5.6 Sol (59). Claude Opus 4.8 (56), GPT-5.6 Terra (55), and GPT-5.5 (55) follow. Below: In the Coding Agent Index, GPT-5.6 Sol tops the chart in Codex with 80 points, ahead of GPT-5.6 Terra (77), Claude Fable 5 in Claude Code (77), and GPT-5.5 in Codex (76). | Image: Artificial Analysis

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Sol costs $1.04 per task, about one-third of what Fable 5 charges. The smaller variants, Terra and Luna, cost 50 and 80 percent less than Sol, respectively. According to Artificial Analysis, Sol "defines a new Pareto frontier of Intelligence vs Output Tokens per Task." The full benchmark data is available here.