OpenAI's next-generation family — Sol, Terra, and Luna. Sol is OpenAI's strongest model to date, with a new max reasoning effort and an ultra sub-agent mode. Also searched as ChatGPT 5.6.
Flagship
Sol
Balanced
Terra
Fast & cheap
Luna
Access
Preview
No hype, no invented specs.OpenAI hasn't published official GPT-5.6 pricing, context windows, or benchmark scores yet — it's a limited preview. Everything below is confirmed from OpenAI's announcement. We'll add verified numbers here the moment they're released, so this is the page to bookmark.
Sol, Terra & Luna: the three GPT-5.6 models
GPT-5.6 ships as a family, not a single model — pick the tier that fits the job.
GPT-5.6 Sol
Flagship
OpenAI's strongest model to date. Agentic gains in coding, biology, and cybersecurity, a new "max" reasoning effort, and an "ultra" mode that spins up sub-agents for complex work.
Sets a new state of the art on Terminal-Bench 2.1 (command-line agent tasks)
Stronger on GeneBench v1 than GPT-5.5 while using fewer tokens
New "ultra" mode coordinates sub-agents for long, multi-step work
GPT-5.6 Terra
Balanced
The everyday workhorse: competitive with GPT-5.5 quality at roughly half the cost. The likely default for most production workloads once it's generally available.
Matches GPT-5.5-class performance at about 2x lower cost
Aimed at high-volume, cost-sensitive day-to-day work
Exact pricing not yet published by OpenAI
GPT-5.6 Luna
Fast & cheap
OpenAI's fastest, lowest-cost model in the 5.6 family — built for latency-sensitive and high-throughput tasks where speed and price matter more than peak reasoning.
OpenAI's lowest published price point in the 5.6 lineup
Best fit for chat, classification, and high-volume automation
Exact pricing and context window not yet published
What's new in GPT-5.6
The confirmed upgrades over GPT-5.5, straight from OpenAI's announcement.
"max" reasoning effort
A new effort level above the existing tiers, giving Sol more room to think on the hardest problems — for agentic coding, scientific reasoning, and long-horizon planning.
"ultra" sub-agent mode
For complex work, Sol can run as a coordinator that delegates to sub-agents — closing the gap with multi-agent setups (a direction Anthropic shipped natively in Opus 4.8).
Agentic coding — new SOTA
Sol sets a new state of the art on Terminal-Bench 2.1, which tests real command-line workflows that require planning, iteration, and tool coordination.
Science & biology gains
On GeneBench v1, Sol beats GPT-5.5 while using fewer tokens — a signal of more efficient reasoning, not just a bigger model.
Stronger safety stack
GPT-5.6 ships with OpenAI's most robust safety stack to date, with strengthened protections around higher-risk activity, sensitive cyber requests, and repeated misuse.
Three tiers, one family
Sol, Terra, and Luna span flagship, balanced, and budget — so you can match the model to the job instead of paying flagship rates for everything.
How GPT-5.6 stacks up — what we know today
GPT-5.6's full specs aren't public yet, so here's the confirmed positioning against the models you can use right now.
Dimension
GPT-5.6 Sol
Today's frontier (GPT-5.5 · Opus 4.8 · Gemini 3.1 Pro)
Status
Limited preview (Jun 26, 2026)
Generally available
Headline strength
Agentic coding — new Terminal-Bench 2.1 SOTA
Opus 4.8: 69.2% SWE-Bench Pro · GPT-5.5: 82.7% Terminal-Bench
Reasoning modes
New "max" effort + "ultra" sub-agents
Opus 4.8: native parallel subagents
Pricing
Not published (Terra ~2x cheaper than GPT-5.5)
GPT-5.5 & Opus 4.8: $5 / 1M input
Context window
Not published
GPT-5.5: 1M · Opus 4.8: 1M · Gemini 3.1 Pro: 2M
Rival figures are verified UseRightAI catalog data. GPT-5.6 numbers are intentionally left blank until OpenAI publishes them.
Where it stands at announcement — and what OpenAI says comes next.
Right now
Limited preview to a small group of trusted partners
Coming weeks
Broader rollout planned across ChatGPT, Codex, and the API
Model family
GPT-5.6 Sol · GPT-5.6 Terra · GPT-5.6 Luna
Building today? Until GPT-5.6 is generally available with published pricing, ship on a model you can rely on now — see the best AI for coding and the live API pricing table. We'll update this page with GPT-5.6 access details the moment they go live.
GPT-5.6 is OpenAI's next-generation model family, announced June 26, 2026. It ships as three models: Sol (the flagship and OpenAI's strongest model to date), Terra (a balanced model competitive with GPT-5.5 at roughly half the cost), and Luna (the fastest, lowest-cost option). It launched as a limited preview to select partners, with broader ChatGPT, Codex, and API access planned in the coming weeks.
What are GPT-5.6 Sol, Terra, and Luna?
They're the three tiers of the GPT-5.6 family. Sol is the flagship — strongest at agentic coding, biology, and cybersecurity, with a new 'max' reasoning effort and an 'ultra' sub-agent mode. Terra is the balanced everyday model, matching GPT-5.5 quality at about 2x lower cost. Luna is the fast, cheap model for latency-sensitive and high-volume work.
When was GPT-5.6 released?
OpenAI announced GPT-5.6 on June 26, 2026. At launch it is a limited preview available only to a small group of trusted partners; OpenAI says general availability across ChatGPT, Codex, and the API will follow in the coming weeks.
How much does GPT-5.6 cost?
OpenAI has not published official GPT-5.6 API pricing yet. The only pricing guidance so far is directional: Terra is described as roughly 2x cheaper than GPT-5.5, and Luna is the lowest-cost model in the family. We'll post the exact per-million-token rates here the moment OpenAI confirms them.
Is GPT-5.6 available now, and how do I access it?
Not for everyone yet. GPT-5.6 is in a limited preview restricted to a small group of trusted partners. OpenAI plans to roll it out more broadly through ChatGPT, Codex, and the API in the coming weeks. There is no public API model ID or ChatGPT toggle for general users at announcement.
GPT-5.6 vs GPT-5.5 — what's better?
GPT-5.6 Sol is positioned as a clear step up from GPT-5.5: it sets a new state of the art on Terminal-Bench 2.1 for agentic coding, improves on GeneBench v1 while using fewer tokens, and adds 'max' effort plus an 'ultra' sub-agent mode. GPT-5.5 remains the model you can actually use at scale today ($5/1M input, 1M context, 82.7% Terminal-Bench). Until full GPT-5.6 benchmarks and pricing are published, GPT-5.5 is the safe production choice.
What is GPT-5.6's "ultra" mode?
'Ultra' is a new mode in which the model coordinates sub-agents to tackle complex, multi-step work — delegating pieces of a task and combining the results. It pairs with a new 'max' reasoning effort for the hardest problems. It's conceptually similar to the native parallel-subagent approach Anthropic shipped in Claude Opus 4.8.
How does GPT-5.6 compare to Claude Opus 4.8?
Claude Opus 4.8 is the current public coding frontier at 69.2% SWE-Bench Pro for $5/$25 per million tokens. GPT-5.6 Sol claims a new SOTA on Terminal-Bench 2.1, but OpenAI hasn't released SWE-Bench, pricing, or context-window numbers yet — so a true head-to-head isn't possible until the specs land. We'll publish a full GPT-5.6 vs Opus 4.8 comparison the moment they do.