Quick Answer
GPT-5.6 Luna Now Free & Unlimited on ChatGPT
The Short Answer
On August 6, 2026, OpenAI made GPT-5.6 Luna the default model for free and “Go” ChatGPT users, with unlimited text chats and a new “Think button” for on-demand reasoning. Paid users got an updated, more focused GPT-5.6 Sol plus a reasoning-effort slider. Luna’s API price was already cut 80% on July 30 to $0.20/$1.20 per MTok.
What Changed (August 6, 2026)
| Tier | Change |
|---|---|
| Free / Go | GPT-5.6 Luna default, unlimited text chats, Think button |
| Plus / Pro | GPT-5.6 Sol update (more direct, factual, focused) + reasoning slider |
Why It Matters
- Frontier-family model, free and unlimited. Putting Luna — part of the GPT-5.6 generation — under free users with no text-chat cap is an aggressive retention/acquisition move against Gemini’s free tier and free Claude.
- The 80% price cut set it up. On July 30, 2026 OpenAI slashed Luna’s API price by 80% to $0.20 input / $1.20 output per MTok (and Terra by 20%). Cheap inference is what makes “unlimited free” economically viable.
- User-controlled reasoning. The Think button (free) and slider (paid) hand users the effort dial — trading latency and tokens for depth only when needed. It’s a UX admission that not every query needs maximum reasoning.
How Luna Fits the Lineup
| Model | Input /MTok | Output /MTok | Role |
|---|---|---|---|
| GPT-5.6 Luna | $0.20 | $1.20 | Cheapest; free ChatGPT default |
| GPT-5.6 Terra | $2 | $12 | Mid-tier (cut 20% Jul 30) |
| GPT-5.6 Sol | $5 | $30 | Flagship generalist |
Luna is the value floor of the family — great for everyday chat, weaker than Sol on hard coding/reasoning.
Watch Outs
- “Unlimited text chats” ≠ unlimited everything. Image, voice, and tool-heavy usage may still be metered; the unlimited claim is scoped to text.
- Luna is the small model. For hard coding or novel reasoning, Sol or Claude Opus 5 still win — Luna trades depth for cost and speed.
- Rollouts stagger. Availability may reach users over days after the August 6 announcement.
Verdict
Making GPT-5.6 Luna the free, unlimited-text default on August 6, 2026 — powered by its July 30 80% price cut — is OpenAI competing hard on the free tier. For casual users it’s a big upgrade; for demanding coding and reasoning work, the paid Sol tier (and rivals like Claude Opus 5) still lead.
Sources
- Unite.AI — OpenAI gives free ChatGPT users unlimited text chats on GPT-5.6 Luna: unite.ai
- OpenAI — Improving GPT-5.6 Sol in ChatGPT: openai.com
- OpenAI — GPT-5.6 (July 30 price-cut note): openai.com
- BleepingComputer — OpenAI rolls out a major ChatGPT upgrade: bleepingcomputer.com