Comparison
ChatGPT Free vs Plus in 2026 — Luna, Think, and the Sol slider
OpenAI's October plan page and Work/Codex model guide differ on GPT-6 Chat availability. Here's the dated August refresh, the current plan summary, and what to verify in your account.
Surface availability checked on 1 October 2026. OpenAI's current consumer pricing page lists GPT-6 models for Plus and Pro, while its Work/Codex model guide says GPT-6.1 Sol, GPT-6 Sol and GPT-6 Luna are not available in Chat. The sources do not agree on the consumer Chat rollout; check the model picker in the account and client you plan to use.
On 6 August 2026 OpenAI announced a ChatGPT refresh. Free and Go would move to GPT-5.6 Luna as the default chat model that week, with unlimited text chats under normal use and a Think control starting the following week. At that time, Plus and Pro received an updated GPT-5.6 Sol and effort slider. OpenAI's October 1 plan page now lists GPT-6 models on Plus and Pro, though its Work/Codex guide describes those models as unavailable in Chat. Treat the August details as historical; check the current account picker for today's options. File uploads, image tools, advanced connectors, and other product features still have limits — “unlimited” does not mean every feature is unlimited.
This article is a buyer’s map of Free/Go versus Plus/Pro after that refresh. It is not a claim that ChatGPT Chat equals the API, Codex, or ChatGPT Work. Those surfaces can lag or bill differently, and mixing them in one spreadsheet is how teams overpay.
The later GPT-6.1 Sol release introduced a documentation split: the Work/Codex model guide describes GPT-6.1 Sol as a Work/Codex model, while the current consumer pricing page lists it for Plus and Pro. The API remains a separate product and billing path.
What Free and Go buyers should actually expect
OpenAI's current pricing page lists GPT-5.6 Luna for Free and Go and says text chats are unlimited subject to abuse guardrails. Treat this as the published plan summary, not a guaranteed account-level quota; tool and model availability can still vary.
Think is a per-message control on Free/Go: you ask for a deeper pass on Luna when the first answer is thin. It is not a free Sol subscription, and it is not the same as Plus’s Sol effort slider. Treat Think as a quality boost for hard questions, not as a reason to abandon paid tiers if you need Sol-class Chat behaviour all day.
Tools still matter. Uploading PDFs, generating images, browsing, and other feature dials remain limited on Free/Go. If your weekly work is “paste a brief and get a draft,” Free/Go Luna may be enough. If your weekly work is “upload five decks, image every slide, and keep a long project memory,” you are buying Plus for tools and Sol — not merely for “better prose.”
ChatGPT Work and Codex did not automatically inherit the August Chat refresh. OpenAI’s own note frames the update as Chat-optimised; workplace and coding surfaces can stay on previously released July Sol/Luna builds. If your company seat is Work, do not assume the consumer Chat changelog applies the same day.
What Plus and Pro buyers should actually expect
Sol in Chat after 6 August is the refreshed Sol with an effort slider: quick replies at the low end, longer reasoning at the high end. You are paying for subscription product features and Sol-class Chat behaviour — not for unlimited frontier API. API volume still bills on API IDs and rate cards. Coding agents still live in harness decisions (Cursor, Claude Code, OpenAI Codex), not inside a Plus receipt.
Pro remains the high-ceiling consumer/team Chat product for people who burn through Plus limits. It does not magically unify Chat, Work, Codex, and API into one meter. When finance asks “what does OpenAI cost us?,” answer with four lines: Chat seats, Work seats, Codex/harness seats, and API spend. Collapsing those lines is how September surprises happen.
Read the catalog profiles for Sol and Luna when the job is automation or evaluation harnesses. Chat marketing copy is a poor substitute for model IDs in production.
GPT-6 availability differs between current OpenAI pages
OpenAI released GPT-6 Sol and GPT-6 Luna on 22 September 2026 and GPT-6.1 Sol on 29 September. As checked on 1 October, its consumer pricing page lists GPT-6.1 Sol, GPT-6 Astra, GPT-6 Sol and GPT-6 Luna for Plus, with expanded access on Pro; it lists none of those for Free or Go. The separate Work/Codex model guide says GPT-6.1 Sol, GPT-6 Sol and GPT-6 Luna are not available in Chat and instead lists availability in Work and Codex. Because these current first-party pages differ, use the model picker in your own account and product surface as the final check.
| Plan | Consumer plan page, checked 1 Oct | Work/Codex model guide |
|---|---|---|
| Free / Go | GPT-5.6 Luna; no GPT-6 models listed | GPT-6 Luna in desktop app when available |
| Plus | GPT-6.1 Sol, GPT-6 Astra, GPT-6 Sol and GPT-6 Luna listed | GPT-6.1 Sol, GPT-6 Sol and GPT-6 Luna available in Work/Codex when available |
| Pro | Same GPT-6 models listed, with expanded access; Pro reasoning powered by Astra | GPT-6.1 Sol, GPT-6 Sol and GPT-6 Luna available in Work/Codex when available |
What that means for this decision:
- OpenAI's pages conflict on Chat rollout. The pricing page describes GPT-6 model access for Plus/Pro; the Work/Codex guide says those models are not in Chat. Confirm availability in the actual account and client.
- The Work/Codex guide also lists GPT-6 Luna for the desktop app, while the consumer plan table lists GPT-5.6 Luna for Free/Go. Because these pages describe different surfaces and appear to disagree, verify the model picker and plan in the client you intend to use.
- Do not buy a plan based on an assumed surface. The published plan page and account picker should both be checked for the product and model you need.
- Enterprise admins must switch them on. On Enterprise plans, Sol and Luna appear only once an administrator enables them.
- API buyers are unaffected by any of this.
gpt-6-sol($2/$10) halves GPT-5.6 Sol's promotional API rate.gpt-6-luna($0.10/$0.50) halves its predecessor's input rate and lowers output from $1.20 to $0.50. See the OpenAI tier guide.
OpenAI's current consumer pricing page lists GPT-6 models for Plus/Pro, but its Work/Codex guide says GPT-6.1 Sol, GPT-6 Sol and GPT-6 Luna are not available in Chat. Until those first-party pages agree, compare the published plan table with the model picker in your account before buying for a specific Chat model.
How to choose in one afternoon
- List the jobs that happen every week: drafting, research chat, file-heavy analysis, image work, coding agents, API automation.
- Mark which jobs are ChatGPT Chat versus Work versus a coding harness versus raw API.
- Try Free/Go Luna + Think on the Chat jobs for two days. If quality and tool limits are fine, stay. If you need Sol effort control or Plus tool headroom, upgrade for those jobs only.
- Keep API and Codex decisions on their own tabs — see ChatGPT Work vs Chat vs Codex.
Common mistakes
- Still advising Free users that ChatGPT is Instant-only with tiny text caps — that advice is outdated after 6 August 2026.
- Treating Think as “free Sol.”
- Buying Plus because an API project failed — wrong surface.
- Assuming Work and Codex got the Chat Sol refresh on day one.
- Upgrading to Plus for a specific GPT-6 model before checking the account's Chat picker; OpenAI's consumer pricing page and Work/Codex guide currently conflict about Chat availability.
- Comparing Free vs Plus using only sticker monthly price and ignoring tool limits and harness spend.
Routing tip
If your work is API volume, start with the GPT-6 Luna or GPT-6 Sol IDs explicitly and meter tokens. If your work is consumer ChatGPT, Free/Go Luna + Think may be enough until you need Plus/Pro tools or Sol effort control. For coding, run the AI coding assistant finder instead of upgrading Chat seats and hoping. Retire any internal wiki that still says Free ChatGPT is Instant-only and heavily capped for text.
Sources
- OpenAI — ChatGPT Learn model documentation (GPT-6.1 Sol, GPT-6 Sol and GPT-6 Luna are Work/Codex models, not ordinary Chat): https://developers.openai.com/codex/models — checked 2026-10-01
- OpenAI — GPT-6.1 Sol API model documentation: https://developers.openai.com/api/docs/models/gpt-6.1-sol — checked 2026-10-01
- OpenAI — ChatGPT pricing and plan/model table (Free/Go versus Plus/Pro): https://chatgpt.com/pricing/ — checked 2026-10-01
- OpenAI — Work and Codex model availability guide: https://developers.openai.com/codex/models — checked 2026-10-01
- OpenAI — Introducing GPT-6 Sol and Luna (initial September Work/Codex availability and Free/Go desktop rollout): https://openai.com/index/introducing-gpt-6-sol-and-luna/ — accessed 2026-09-26
- Notebookcheck — "ChatGPT Free gets GPT-6 Luna, but only in the desktop app" (24 Sep 2026; Chat defaults; Plus, Pro and Enterprise details): https://www.notebookcheck.net/ChatGPT-Free-gets-GPT-6-Luna-but-only-in-the-desktop-app.1407282.0.html — accessed 2026-09-26
- OpenAI — GPT-5.6 (Sol $4/$20, Terra $2/$12, Luna $0.20/$1.20; 1.05M context): https://openai.com/index/gpt-5-6/ — accessed 2026-08-29
- OpenAI API pricing: https://platform.openai.com/docs/pricing — accessed 2026-08-29
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AI Choice Engine publishes editorial guides to help readers understand fit, trade-offs, and next steps before choosing a tool or provider.
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