Sol replaces manual multi-agent orchestration for teams running the hardest coding and research workloads, not everyday chat. It's the default model inside the enterprise Copilot suite, so most business users already run it without choosing it directly, while cost-sensitive teams should route to a cheaper sibling model instead.
Sol is OpenAI's flagship model, released July 9, 2026, ranking #1 on LMArena Chatbot Arena and scoring 78.5% on SWE-bench Verified. It adds ultra multi-agent coordination and programmatic tool calling that its cheaper siblings, Terra and Luna, simply don't get access to.
Provider: OpenAI · Family: GPT-5.6
Context window: 200,000 tokens · Max output: 64,000
Input modalities: text, image · Output: text, tool-calls, code
About GPT-5.6 Sol
GPT-5.6 Sol is the flagship model of OpenAI's GPT-5.6 family, launched July 9, 2026 for general availability following a limited preview starting June 26, 2026. It sets a new bar for both intelligence and efficiency, leading results across coding, knowledge work, cybersecurity, and science while outperforming previous and competing frontier models with fewer tokens and at lower estimated cost. The model delivers stronger performance per dollar: more successful work for the same spend, or comparable results at lower total cost. A key innovation is ultra mode, OpenAI's highest-capability setting that coordinates multiple agents across parallel workstreams to finish complex tasks faster. This multi-agent coordination, similar to the Codex ultra mode, reduces wall-clock time and improves performance for complex tasks that divide cleanly into independent workstreams. Sol also features stronger computer use and design judgment, making it the most polished collaborator for inspecting, refining, and delivering ready-to-use results, particularly for frontend development with improved layout, visual hierarchy, and design aesthetics. The model introduces programmatic tool calling (PTC), allowing it to write JavaScript to call eligible tools, pass results between calls, and process intermediate outputs in a hosted runtime. PTC is ZDR-compatible with no additional container costs, ideal for bounded, tool-heavy workflows. Explicit prompt caching with cache breakpoints and a half-hour minimum cache life provides predictable caching economics, with cache reads retaining a large discount over uncached input. Persisted reasoning reuses reasoning items across turns via reasoning.context for multi-turn quality and cache efficiency. Reasoning effort supports none, low, medium, high, xhigh, max, plus a pro mode that performs more model work for reliability on difficult tasks, returning a single final answer. Max reasoning effort is reserved for the hardest quality-first workloads. See the pricing FAQ for exact rates. Sol is available on the OpenAI API, ChatGPT, Codex, Microsoft 365 Copilot, Cerebras, and other model gateways. Knowledge cutoff is June 2026.
Pricing
Input $5/M, Output $30/M, Cached input $0.625/M (1.25x base). Cache writes at 1.25x, reads at 90% discount. Explicit cache breakpoints supported. No batch discount at launch. Ultra/multi-agent usage billed at standard token rates. Programmatic tool calling billed at standard rates. Server-side tools (if any) billed separately. Cerebras inference pricing separate.
Key Features
- Ultra Multi-Agent Coordination: Coordinates multiple subagents in parallel across independent workstreams, cutting wall-clock time on complex tasks by 40-60%.
- Programmatic Tool Calling (PTC): The model writes JavaScript to call tools, pass results, and process intermediates in a hosted runtime with no added container costs.
- Explicit Prompt Caching with Breakpoints: Developers mark exact cacheable prefixes and get a heavy discount on cached reads, with a half-hour minimum cache life.
- Pro Reasoning Mode: Performs extended model work for reliability on the hardest tasks, then returns a single final answer instead of a running trace.
- 2x Token Efficiency: Reaches frontier performance using roughly half the output tokens of comparable models, which directly lowers cost and latency.
Pros
- Frontier intelligence (LMArena rank 1) paired with 2x token efficiency gives the best performance per dollar at this capability tier.
- Ultra multi-agent mode is a genuine workflow accelerator for parallelizable engineering tasks.
- Programmatic tool calling eliminates turn overhead for tool-heavy loops and stays ZDR compatible.
- Being the default enterprise Copilot model gives it instant, massive seat distribution and trust.
Cons
- Premium pricing excludes high-volume and cost-sensitive workloads that don't need frontier capability.
- No native audio or video modality; vision only, lagging Gemini 3.1 on multimodal breadth.
- Pro mode and ultra mode add significant latency and token overhead compared to standard mode.
- Multi-agent beta still has coordination inefficiencies, including occasionally overlapping sub-tasks.
Benchmarks
- math: 85.6
- mmlu: 92.8
- mmlu pro: 84.7
- aime 2025: 88.3
- arc agi 2: 28.4
- humaneval: 96.2
- live bench: 68.9
- lmarena elo: 1415
- gpqa diamond: 72.1
- lmarena rank: 1
- aider polyglot: 76.8
- swe bench verified: 78.5
- humanitys last exam: 22.1
- artificial analysis intelligence index: 62
- artificial analysis price blended per m: 17.5
- artificial analysis speed tokens per sec: 75
Frequently Asked Questions
How much does GPT-5.6 Sol cost per 1M tokens?
Sol costs $5 per 1M input tokens and $30 per 1M output tokens, with cached input at $0.625 per 1M, a 90% discount over uncached. Cache writes cost 1.25x the base input rate. There's no batch discount at launch, and Cerebras inference is priced separately.
How does GPT-5.6 Sol compare on benchmarks vs GPT-5.6 Terra?
Sol scores 78.5% on SWE-bench Verified and 72.1% on GPQA Diamond, ahead of Terra on both. Sol also adds ultra multi-agent mode, programmatic tool calling, and a pro reasoning mode that Terra doesn't have, at roughly double Terra's per-token price.
Is GPT-5.6 Sol open source or proprietary?
Sol is proprietary. OpenAI makes it available only through its own products and a short list of gateway partners. There are no downloadable weights and no open license.
Does GPT-5.6 Sol train on user data?
By default OpenAI doesn't train on API inputs or outputs, and Sol is Zero Data Retention eligible for enterprise customers. It's SOC2 Type II, ISO 27001, GDPR, and HIPAA eligible, with US and EU data residency options.
Who is GPT-5.6 Sol best for and who should avoid it?
Sol fits senior engineering teams running frontier coding, cybersecurity research, and complex multi-agent workflows where quality matters more than cost. Avoid it for high-volume, low-margin inference or simple conversational tasks; route those to Terra or Luna instead.