3-Line TL;DR
- Google opened Gemini 4 Argon to everyone on October 13: the API, the Gemini app and AI Mode for Pro and Ultra subscribers, and Antigravity for Ultra only
- In my Gemini app use it made things up noticeably less and reasoned better than the previous version, but each question took about 5% of my AI Pro usage meter
- It is clearly frontier-level now and a successor called Carbon is reportedly in testing, but on a $19.99 plan I can't use it enough to rely on it
Out at last, two weeks after the announcement
- Google announced Argon on September 30 for a group of cyber defenders only
- My last post complained that there was still no date for anyone else
- On October 13 Google made it generally available
- Developers get it through the Gemini API at $2 input / $10 output per 1M tokens until November 30, then $4 / $20
- Pro and Ultra subscribers get it in the Gemini app and AI Mode in Search
Fewer made-up answers, and the numbers agree
Source: Artificial Analysis, Argon at high effort, checked October 14, 2026
- In my Gemini app use, Argon made things up noticeably less than the previous version, and its reasoning felt stronger
- Artificial Analysis measured a 15% hallucination rate, the lowest among models scoring 45 or more on its index, against 51% for GPT-6 Astra
- That rate counts how often a model answers wrongly instead of admitting it doesn't know
- Part of the gain is saying "I don't know" more: Argon got 50% of the questions right, Astra 63%
- On the overall index Argon scores 53, tied with Astra and up from 30 for Gemini 3.1 Pro Preview
- Claude Opus 5.5 still leads at 58
5% per question is about 20 questions
HSL chart — my own usage meter reading; limit rules from Gemini Help, checked October 14, 2026
- On my AI Pro plan, each Argon question took about 5% off the usage meter
- At that rate a full meter lasts about 20 questions
- Google counts usage by compute, so prompt complexity, model, features and chat length all change the cost
- Pro limits refresh every five hours, with a weekly cap on top
- So 20 is my rough math for questions like mine, not a fixed Google number
- Twenty questions is enough to be impressed, not enough to work with it
Antigravity says Ultra only
Source: Google announcement, Google One US plans; USD before tax, checked October 14, 2026
- In Antigravity, Google's coding agent app, Argon is listed for AI Ultra subscribers only
- Pro users there see it greyed out as "currently available to Ultra plan subscribers" (Hacker News)
- Ultra starts at $99.99 a month in the US, five times the $19.99 Pro plan
- Long coding sessions are where usage burns fastest, and that is exactly where Pro is shut out
- The other route is the API, paying per token
Frontier status saves face, and Carbon is next
HSL diagram — Google announcements; Carbon from a Business Insider report via secondary coverage
- With Argon, Google is back near the top of the index after Gemini 3.1 Pro Preview's 30
- Business Insider reported on October 9 that Google staff are testing another Gemini 4 build, codenamed Carbon, on an internal coding tool
- One employee said it "feels like Opus 5.5" for coding, which is one opinion with no benchmark
- Google has not said whether Carbon becomes an Argon update or a separate model
- A frontier model out the door and a stronger build already in testing is enough to save face
| What I want | What I would do now |
|---|---|
| Try Argon in chat | Pro at $19.99 works; budget about 20 questions per window |
| Argon in Antigravity for coding | Ultra from $99.99, or the API |
| Better value | Watch for Carbon and the API price change after November 30 |
Community Reactions
- A Hacker News user said Argon isn't available to Pro in Antigravity, while Opus 5.5 and Sol or Astra work on $20 plans, and most people won't pay $100 a month just to try it (Hacker News)
- Another called it "pretty insane" that Pro users don't get even a taste in Antigravity, noting the app includes a sample of Opus 5.5 (Hacker News)
- One commenter called Argon a new leader on cost versus intelligence and said Google is back in the race (Hacker News)
- Another described subscription fatigue now that OpenAI, Anthropic, Meta and Google all have frontier models (Hacker News)
Q&A (Field Notes)
- Q. Is this the long-awaited Gemini 4 Pro?
- Google calls it Gemini 4 Argon, and its announcement does not use a "4 Pro" name
- Q. Do free or AI Plus users get Argon?
- The launch post names only Pro and Ultra for the Gemini app, so check your own account before paying for anything
- Q. Is the API cheaper than a subscription for coding?
- It depends on volume; Artificial Analysis put one index task at $1.99 at the introductory price and $3.98 at the standard price
- Q. Should I upgrade to Ultra just for Antigravity?
- Only if Argon-powered coding is your main job and $80 more a month is fine; otherwise I would wait for Carbon or a price change