--- title: The new GPT-5.6 family: Luna, Terra, Sol | daily.dev description: OpenAI released GPT-5.6 in three sizes — Luna, Terra, and Sol — with pricing ranging from $1/$6 to $5/$30 per million input/output tokens. The models claim... canonical: https://daily.dev/posts/the-new-gpt-5-6-family-luna-terra-sol-nvvgbeebk twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: The new GPT-5.6 family: Luna, Terra, Sol | daily.dev og:description: OpenAI released GPT-5.6 in three sizes — Luna, Terra, and Sol — with pricing ranging from $1/$6 to $5/$30 per million input/output tokens. The models claim... og:url: https://daily.dev/posts/the-new-gpt-5-6-family-luna-terra-sol-nvvgbeebk og:image: https://api.daily.dev/og/posts/NvvgbEeBk.png og:image:alt: The new GPT-5.6 family: Luna, Terra, Sol og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # The new GPT-5.6 family: Luna, Terra, Sol **[Simon Willison](https://daily.dev/sources/simonwillison)** · 4 min read · 1 upvotes · 0 comments ## Summary OpenAI released GPT-5.6 in three sizes — Luna, Terra, and Sol — with pricing ranging from $1/$6 to $5/$30 per million input/output tokens. The models claim strong agentic performance, with Sol scoring 53.6 on the Agents' Last Exam benchmark, outperforming Claude Fable 5 by 13.1 points. Notably, OpenAI published a critique of SWE-Bench Pro the day before the release, estimating ~30% of its tasks are broken — a benchmark where Fable 5 significantly outperformed GPT-5.6 Sol (80% vs 64.6%). New API features include Programmatic Tool Calling (composing JavaScript to orchestrate tool calls), native multi-agent support, explicit prompt cache breakpoints, and an option to skip image resizing. The author notes GPT-5.6 Sol is competent but hasn't yet surpassed Fable 5 for complex coding tasks in personal use. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What are the prices for OpenAI's GPT-5.6 Luna, Terra, and Sol models per million tokens? GPT-5.6 Luna costs $1 per million input tokens and $6 per million output tokens, Terra costs $2.50/$15, and Sol costs $5/$30. For comparison, Claude Opus models are priced at $5/$25 and Claude Fable 5 at $10/$50 per million tokens, though reasoning token volume varies significantly across models for the same task. _Developers comparing model costs before committing to an API can track pricing shifts like these on daily.dev._ ### How does GPT-5.6 Sol perform on SWE-Bench Pro compared to Claude Fable 5? Claude Fable 5 scored 80% on SWE-Bench Pro compared to GPT-5.6 Sol's 64.6%, a result OpenAI itself reported. OpenAI published a separate audit the day before GPT-5.6's launch estimating that roughly 30% of SWE-Bench Pro tasks are broken, which may explain the timing given Sol's weaker showing on that particular benchmark. _Anyone weighing GPT-5.6 against Claude Fable 5 for coding tasks can follow benchmark scrutiny like this on daily.dev._ ### What is Programmatic Tool Calling in OpenAI's GPT-5.6 API? Programmatic Tool Calling is a new GPT-5.6 API feature that allows the model to compose and run JavaScript to orchestrate tool calls within a single turn, rather than making one tool call at a time. It resembles Anthropic's dynamic filtering mechanism for its web search tool, and may help bridge the gap between MCP-style tool use and full terminal sessions that chain CLI utilities. _Engineers building agentic tool-calling workflows can keep tabs on API features like this via daily.dev._ --- Tags: [#ai](https://daily.dev/tags/ai), [#llm](https://daily.dev/tags/llm), [#ai-agents](https://daily.dev/tags/ai-agents), [#openai](https://daily.dev/tags/openai), [#gpt](https://daily.dev/tags/gpt) [View this post on daily.dev](https://daily.dev/posts/the-new-gpt-5-6-family-luna-terra-sol-nvvgbeebk) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"The new GPT-5.6 family: Luna, Terra, Sol","url":"https://daily.dev/posts/the-new-gpt-5-6-family-luna-terra-sol-nvvgbeebk","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/the-new-gpt-5-6-family-luna-terra-sol-nvvgbeebk"},"datePublished":"2026-07-09T19:47:37.374Z","dateModified":"2026-09-13T21:17:04.296Z","description":"OpenAI released GPT-5.6 in three sizes — Luna, Terra, and Sol — with pricing ranging from $1/$6 to $5/$30 per million input/output tokens. 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